[PATCH net-next v2 00/12] net: xps: improve the xps maps handling

STALE1987d

Revision v2 of 4 in this series.

20 messages, 3 authors, 2021-02-23 · open the first message on its own page

[PATCH net-next v2 00/12] net: xps: improve the xps maps handling

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:21:18 

Hello,

A small series moving the xps cpus/rxqs retrieval logic in net-sysfs was
sent[1] and while there was no comments asking for modifications in the
patches themselves, we had discussions about other xps related reworks.
In addition to the patches sent in the previous series[1] (included),
this series has extra patches introducing the modifications we
discussed.

The main change is moving dev->num_tc and dev->nr_ids in the xps maps, to
avoid out-of-bound accesses as those two fields can be updated after the
maps have been allocated. This allows further reworks, to improve the
xps code readability and allow to stop taking the rtnl lock when
reading the maps in sysfs.

Finally, the maps are moved to an array in net_device, which simplifies
the code a lot.

One future improvement may be to remove the use of xps_map_mutex from
net/core/dev.c, but that may require extra care.

Thanks!
Antoine

[1] https://lore.kernel.org/netdev/20210106180428.722521-1-atenart@kernel.org/

Since v1:
  - Reordered the patches to improve readability and avoid introducing
    issues in between patches.
  - Use dev_maps->nr_ids to allocate the mask in xps_queue_show but
    still default to nr_cpu_ids/dev->num_rx_queues in xps_queue_show
    when dev_maps hasn't been allocated yet for backward compatibility.

Antoine Tenart (12):
  net-sysfs: convert xps_cpus_show to bitmap_zalloc
  net-sysfs: store the return of get_netdev_queue_index in an unsigned
    int
  net-sysfs: make xps_cpus_show and xps_rxqs_show consistent
  net: embed num_tc in the xps maps
  net: embed nr_ids in the xps maps
  net: assert the rtnl lock is held when calling __netif_set_xps_queue
  net: remove the xps possible_mask
  net: move the xps maps to an array
  net-sysfs: remove the rtnl lock when accessing the xps maps
  net: add an helper to copy xps maps to the new dev_maps
  net: improve queue removal readability in __netif_set_xps_queue
  net-sysfs: move the xps cpus/rxqs retrieval in a common function

 drivers/net/virtio_net.c  |   2 +-
 include/linux/netdevice.h |  27 ++++-
 net/core/dev.c            | 233 +++++++++++++++++++-------------------
 net/core/net-sysfs.c      | 165 +++++++++------------------
 4 files changed, 194 insertions(+), 233 deletions(-)

-- 
2.29.2

[PATCH net-next v2 01/12] net-sysfs: convert xps_cpus_show to bitmap_zalloc

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:21:38 

Use bitmap_zalloc instead of zalloc_cpumask_var in xps_cpus_show to
align with xps_rxqs_show. This will improve maintenance and allow us to
factorize the two functions. The function should behave the same.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/net-sysfs.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index daf502c13d6d..e052fc5f7e94 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1320,8 +1320,7 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	int cpu, len, ret, num_tc = 1, tc = 0;
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
-	cpumask_var_t mask;
-	unsigned long index;
+	unsigned long *mask, index;
 
 	if (!netif_is_multiqueue(dev))
 		return -ENOENT;
@@ -1349,7 +1348,8 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 		}
 	}
 
-	if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
+	mask = bitmap_zalloc(nr_cpu_ids, GFP_KERNEL);
+	if (!mask) {
 		ret = -ENOMEM;
 		goto err_rtnl_unlock;
 	}
@@ -1367,7 +1367,7 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 			for (i = map->len; i--;) {
 				if (map->queues[i] == index) {
-					cpumask_set_cpu(cpu, mask);
+					set_bit(cpu, mask);
 					break;
 				}
 			}
@@ -1377,8 +1377,8 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 	rtnl_unlock();
 
-	len = snprintf(buf, PAGE_SIZE, "%*pb\n", cpumask_pr_args(mask));
-	free_cpumask_var(mask);
+	len = bitmap_print_to_pagebuf(false, buf, mask, nr_cpu_ids);
+	bitmap_free(mask);
 	return len < PAGE_SIZE ? len : -EINVAL;
 
 err_rtnl_unlock:
-- 
2.29.2

[PATCH net-next v2 02/12] net-sysfs: store the return of get_netdev_queue_index in an unsigned int

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:22:05 

In net-sysfs, get_netdev_queue_index returns an unsigned int. Some of
its callers use an unsigned long to store the returned value. Update the
code to be consistent, this should only be cosmetic.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/net-sysfs.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index e052fc5f7e94..5a39e9b38e5f 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1320,7 +1320,8 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	int cpu, len, ret, num_tc = 1, tc = 0;
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
-	unsigned long *mask, index;
+	unsigned long *mask;
+	unsigned int index;
 
 	if (!netif_is_multiqueue(dev))
 		return -ENOENT;
@@ -1390,7 +1391,7 @@ static ssize_t xps_cpus_store(struct netdev_queue *queue,
 			      const char *buf, size_t len)
 {
 	struct net_device *dev = queue->dev;
-	unsigned long index;
+	unsigned int index;
 	cpumask_var_t mask;
 	int err;
 
@@ -1432,7 +1433,8 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 	int j, len, ret, num_tc = 1, tc = 0;
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
-	unsigned long *mask, index;
+	unsigned long *mask;
+	unsigned int index;
 
 	index = get_netdev_queue_index(queue);
 
@@ -1494,7 +1496,8 @@ static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf,
 {
 	struct net_device *dev = queue->dev;
 	struct net *net = dev_net(dev);
-	unsigned long *mask, index;
+	unsigned long *mask;
+	unsigned int index;
 	int err;
 
 	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
-- 
2.29.2

[PATCH net-next v2 03/12] net-sysfs: make xps_cpus_show and xps_rxqs_show consistent

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:22:05 

Make the implementations of xps_cpus_show and xps_rxqs_show to converge,
as the two share the same logic but diverted over time. This should not
modify their behaviour but will help future changes and improve
maintenance.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/net-sysfs.c | 33 ++++++++++++++++++---------------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 5a39e9b38e5f..3915b1826814 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1317,7 +1317,7 @@ static const struct attribute_group dql_group = {
 static ssize_t xps_cpus_show(struct netdev_queue *queue,
 			     char *buf)
 {
-	int cpu, len, ret, num_tc = 1, tc = 0;
+	int j, len, ret, num_tc = 1, tc = 0;
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
 	unsigned long *mask;
@@ -1357,23 +1357,26 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 	rcu_read_lock();
 	dev_maps = rcu_dereference(dev->xps_cpus_map);
-	if (dev_maps) {
-		for_each_possible_cpu(cpu) {
-			int i, tci = cpu * num_tc + tc;
-			struct xps_map *map;
-
-			map = rcu_dereference(dev_maps->attr_map[tci]);
-			if (!map)
-				continue;
-
-			for (i = map->len; i--;) {
-				if (map->queues[i] == index) {
-					set_bit(cpu, mask);
-					break;
-				}
+	if (!dev_maps)
+		goto out_no_maps;
+
+	for (j = -1; j = netif_attrmask_next(j, NULL, nr_cpu_ids),
+	     j < nr_cpu_ids;) {
+		int i, tci = j * num_tc + tc;
+		struct xps_map *map;
+
+		map = rcu_dereference(dev_maps->attr_map[tci]);
+		if (!map)
+			continue;
+
+		for (i = map->len; i--;) {
+			if (map->queues[i] == index) {
+				set_bit(j, mask);
+				break;
 			}
 		}
 	}
+out_no_maps:
 	rcu_read_unlock();
 
 	rtnl_unlock();
-- 
2.29.2

[PATCH net-next v2 09/12] net-sysfs: remove the rtnl lock when accessing the xps maps

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:24:11 

Now that nr_ids and num_tc are stored in the xps dev_maps, which are RCU
protected, we do not have the need to protect the xps_cpus_show and
xps_rxqs_show functions with the rtnl lock.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/net-sysfs.c | 26 ++++----------------------
 1 file changed, 4 insertions(+), 22 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index c2276b589cfb..6ce5772e799e 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1328,17 +1328,12 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 	index = get_netdev_queue_index(queue);
 
-	if (!rtnl_trylock())
-		return restart_syscall();
-
 	/* If queue belongs to subordinate dev use its map */
 	dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
 
 	tc = netdev_txq_to_tc(dev, index);
-	if (tc < 0) {
-		ret = -EINVAL;
-		goto err_rtnl_unlock;
-	}
+	if (tc < 0)
+		return -EINVAL;
 
 	rcu_read_lock();
 	dev_maps = rcu_dereference(dev->xps_maps[XPS_CPUS]);
@@ -1371,16 +1366,12 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 out_no_maps:
 	rcu_read_unlock();
 
-	rtnl_unlock();
-
 	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
 	bitmap_free(mask);
 	return len < PAGE_SIZE ? len : -EINVAL;
 
 err_rcu_unlock:
 	rcu_read_unlock();
-err_rtnl_unlock:
-	rtnl_unlock();
 	return ret;
 }
 
@@ -1435,14 +1426,9 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 
 	index = get_netdev_queue_index(queue);
 
-	if (!rtnl_trylock())
-		return restart_syscall();
-
 	tc = netdev_txq_to_tc(dev, index);
-	if (tc < 0) {
-		ret = -EINVAL;
-		goto err_rtnl_unlock;
-	}
+	if (tc < 0)
+		return -EINVAL;
 
 	rcu_read_lock();
 	dev_maps = rcu_dereference(dev->xps_maps[XPS_RXQS]);
@@ -1475,8 +1461,6 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 out_no_maps:
 	rcu_read_unlock();
 
-	rtnl_unlock();
-
 	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
 	bitmap_free(mask);
 
@@ -1484,8 +1468,6 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 
 err_rcu_unlock:
 	rcu_read_unlock();
-err_rtnl_unlock:
-	rtnl_unlock();
 	return ret;
 }
 
-- 
2.29.2

[PATCH net-next v2 06/12] net: assert the rtnl lock is held when calling __netif_set_xps_queue

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:24:24 

Add ASSERT_RTNL at the top of __netif_set_xps_queue and add a comment
about holding the rtnl lock before the function.

Suggested-by: Alexander Duyck <redacted>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/dev.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 1f7df0bd415c..abbb2ae6b3ed 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2605,7 +2605,7 @@ static struct xps_map *expand_xps_map(struct xps_map *map, int attr_index,
 	return new_map;
 }
 
-/* Must be called under cpus_read_lock */
+/* Must be called under rtnl_lock and cpus_read_lock */
 int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 			  u16 index, bool is_rxqs_map)
 {
@@ -2617,6 +2617,8 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	struct xps_map *map, *new_map;
 	unsigned int nr_ids;
 
+	ASSERT_RTNL();
+
 	if (dev->num_tc) {
 		/* Do not allow XPS on subordinate device directly */
 		num_tc = dev->num_tc;
-- 
2.29.2

[PATCH net-next v2 05/12] net: embed nr_ids in the xps maps

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:25:22 

Embed nr_ids (the number of cpu for the xps cpus map, and the number of
rxqs for the xps cpus map) in dev_maps. That will help not accessing out
of bound memory if those values change after dev_maps was allocated.

Suggested-by: Alexander Duyck <redacted>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 include/linux/netdevice.h |  4 ++++
 net/core/dev.c            | 34 +++++++++++++++-------------------
 net/core/net-sysfs.c      | 38 ++++++++++++++++++++++----------------
 3 files changed, 41 insertions(+), 35 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d7d3c646d40d..40683b6eee54 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -780,6 +780,9 @@ struct xps_map {
 /*
  * This structure holds all XPS maps for device.  Maps are indexed by CPU.
  *
+ * We keep track of the number of cpus/rxqs used when the struct is allocated,
+ * in nr_ids. This will help not accessing out-of-bound memory.
+ *
  * We keep track of the number of traffic classes used when the struct is
  * allocated, in num_tc. This will be used to navigate the maps, to ensure we're
  * not crossing its upper bound, as the original dev->num_tc can be updated in
@@ -787,6 +790,7 @@ struct xps_map {
  */
 struct xps_dev_maps {
 	struct rcu_head rcu;
+	unsigned int nr_ids;
 	s16 num_tc;
 	struct xps_map __rcu *attr_map[]; /* Either CPUs map or RXQs map */
 };
diff --git a/net/core/dev.c b/net/core/dev.c
index 7c5e2c614723..1f7df0bd415c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2506,14 +2506,14 @@ static void reset_xps_maps(struct net_device *dev,
 }
 
 static void clean_xps_maps(struct net_device *dev, const unsigned long *mask,
-			   struct xps_dev_maps *dev_maps, unsigned int nr_ids,
-			   u16 offset, u16 count, bool is_rxqs_map)
+			   struct xps_dev_maps *dev_maps, u16 offset, u16 count,
+			   bool is_rxqs_map)
 {
+	unsigned int nr_ids = dev_maps->nr_ids;
 	bool active = false;
 	int i, j;
 
-	for (j = -1; j = netif_attrmask_next(j, mask, nr_ids),
-	     j < nr_ids;)
+	for (j = -1; j = netif_attrmask_next(j, mask, nr_ids), j < nr_ids;)
 		active |= remove_xps_queue_cpu(dev, dev_maps, j, offset,
 					       count);
 	if (!active)
@@ -2533,7 +2533,6 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
 {
 	const unsigned long *possible_mask = NULL;
 	struct xps_dev_maps *dev_maps;
-	unsigned int nr_ids;
 
 	if (!static_key_false(&xps_needed))
 		return;
@@ -2543,11 +2542,9 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
 
 	if (static_key_false(&xps_rxqs_needed)) {
 		dev_maps = xmap_dereference(dev->xps_rxqs_map);
-		if (dev_maps) {
-			nr_ids = dev->num_rx_queues;
-			clean_xps_maps(dev, possible_mask, dev_maps, nr_ids,
-				       offset, count, true);
-		}
+		if (dev_maps)
+			clean_xps_maps(dev, possible_mask, dev_maps, offset,
+				       count, true);
 	}
 
 	dev_maps = xmap_dereference(dev->xps_cpus_map);
@@ -2556,9 +2553,7 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
 
 	if (num_possible_cpus() > 1)
 		possible_mask = cpumask_bits(cpu_possible_mask);
-	nr_ids = nr_cpu_ids;
-	clean_xps_maps(dev, possible_mask, dev_maps, nr_ids, offset, count,
-		       false);
+	clean_xps_maps(dev, possible_mask, dev_maps, offset, count, false);
 
 out_no_maps:
 	mutex_unlock(&xps_map_mutex);
@@ -2672,6 +2667,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 				return -ENOMEM;
 			}
 
+			new_dev_maps->nr_ids = nr_ids;
 			new_dev_maps->num_tc = num_tc;
 		}
 
@@ -2786,12 +2782,12 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		goto out_no_maps;
 
 	/* removes tx-queue from unused CPUs/rx-queues */
-	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
-	     j < nr_ids;) {
+	for (j = -1; j = netif_attrmask_next(j, possible_mask, dev_maps->nr_ids),
+	     j < dev_maps->nr_ids;) {
 		for (i = tc, tci = j * dev_maps->num_tc; i--; tci++)
 			active |= remove_xps_queue(dev_maps, tci, index);
-		if (!netif_attr_test_mask(j, mask, nr_ids) ||
-		    !netif_attr_test_online(j, online_mask, nr_ids))
+		if (!netif_attr_test_mask(j, mask, dev_maps->nr_ids) ||
+		    !netif_attr_test_online(j, online_mask, dev_maps->nr_ids))
 			active |= remove_xps_queue(dev_maps, tci, index);
 		for (i = dev_maps->num_tc - tc, tci++; --i; tci++)
 			active |= remove_xps_queue(dev_maps, tci, index);
@@ -3947,7 +3943,7 @@ static int __get_xps_queue_idx(struct net_device *dev, struct sk_buff *skb,
 	struct xps_map *map;
 	int queue_index = -1;
 
-	if (tc >= dev_maps->num_tc)
+	if (tc >= dev_maps->num_tc || tci >= dev_maps->nr_ids)
 		return queue_index;
 
 	tci *= dev_maps->num_tc;
@@ -3986,7 +3982,7 @@ static int get_xps_queue(struct net_device *dev, struct net_device *sb_dev,
 	if (dev_maps) {
 		int tci = sk_rx_queue_get(sk);
 
-		if (tci >= 0 && tci < dev->num_rx_queues)
+		if (tci >= 0)
 			queue_index = __get_xps_queue_idx(dev, skb, dev_maps,
 							  tci);
 	}
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index c1d4d3e712a9..e544e5f2467c 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1319,9 +1319,9 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 {
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
+	unsigned int index, nr_ids;
 	int j, len, ret, tc = 0;
 	unsigned long *mask;
-	unsigned int index;
 
 	if (!netif_is_multiqueue(dev))
 		return -ENOENT;
@@ -1340,19 +1340,20 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 		goto err_rtnl_unlock;
 	}
 
-	mask = bitmap_zalloc(nr_cpu_ids, GFP_KERNEL);
+	rcu_read_lock();
+	dev_maps = rcu_dereference(dev->xps_cpus_map);
+	nr_ids = dev_maps ? dev_maps->nr_ids : nr_cpu_ids;
+
+	mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
 	if (!mask) {
 		ret = -ENOMEM;
-		goto err_rtnl_unlock;
+		goto err_rcu_unlock;
 	}
 
-	rcu_read_lock();
-	dev_maps = rcu_dereference(dev->xps_cpus_map);
 	if (!dev_maps || tc >= dev_maps->num_tc)
 		goto out_no_maps;
 
-	for (j = -1; j = netif_attrmask_next(j, NULL, nr_cpu_ids),
-	     j < nr_cpu_ids;) {
+	for (j = -1; j = netif_attrmask_next(j, NULL, nr_ids), j < nr_ids;) {
 		int i, tci = j * dev_maps->num_tc + tc;
 		struct xps_map *map;
 
@@ -1372,10 +1373,12 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 	rtnl_unlock();
 
-	len = bitmap_print_to_pagebuf(false, buf, mask, nr_cpu_ids);
+	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
 	bitmap_free(mask);
 	return len < PAGE_SIZE ? len : -EINVAL;
 
+err_rcu_unlock:
+	rcu_read_unlock();
 err_rtnl_unlock:
 	rtnl_unlock();
 	return ret;
@@ -1426,9 +1429,9 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 {
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
+	unsigned int index, nr_ids;
 	int j, len, ret, tc = 0;
 	unsigned long *mask;
-	unsigned int index;
 
 	index = get_netdev_queue_index(queue);
 
@@ -1441,19 +1444,20 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 		goto err_rtnl_unlock;
 	}
 
-	mask = bitmap_zalloc(dev->num_rx_queues, GFP_KERNEL);
+	rcu_read_lock();
+	dev_maps = rcu_dereference(dev->xps_rxqs_map);
+	nr_ids = dev_maps ? dev_maps->nr_ids : dev->num_rx_queues;
+
+	mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
 	if (!mask) {
 		ret = -ENOMEM;
-		goto err_rtnl_unlock;
+		goto err_rcu_unlock;
 	}
 
-	rcu_read_lock();
-	dev_maps = rcu_dereference(dev->xps_rxqs_map);
 	if (!dev_maps || tc >= dev_maps->num_tc)
 		goto out_no_maps;
 
-	for (j = -1; j = netif_attrmask_next(j, NULL, dev->num_rx_queues),
-	     j < dev->num_rx_queues;) {
+	for (j = -1; j = netif_attrmask_next(j, NULL, nr_ids), j < nr_ids;) {
 		int i, tci = j * dev_maps->num_tc + tc;
 		struct xps_map *map;
 
@@ -1473,11 +1477,13 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 
 	rtnl_unlock();
 
-	len = bitmap_print_to_pagebuf(false, buf, mask, dev->num_rx_queues);
+	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
 	bitmap_free(mask);
 
 	return len < PAGE_SIZE ? len : -EINVAL;
 
+err_rcu_unlock:
+	rcu_read_unlock();
 err_rtnl_unlock:
 	rtnl_unlock();
 	return ret;
-- 
2.29.2

[PATCH net-next v2 07/12] net: remove the xps possible_mask

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:25:57 

Remove the xps possible_mask. It was an optimization but we can just
loop from 0 to nr_ids now that it is embedded in the xps dev_maps. That
simplifies the code a bit.

Suggested-by: Alexander Duyck <redacted>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/dev.c       | 43 ++++++++++++++-----------------------------
 net/core/net-sysfs.c |  4 ++--
 2 files changed, 16 insertions(+), 31 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index abbb2ae6b3ed..d0c07ccea2e5 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2505,33 +2505,27 @@ static void reset_xps_maps(struct net_device *dev,
 	kfree_rcu(dev_maps, rcu);
 }
 
-static void clean_xps_maps(struct net_device *dev, const unsigned long *mask,
+static void clean_xps_maps(struct net_device *dev,
 			   struct xps_dev_maps *dev_maps, u16 offset, u16 count,
 			   bool is_rxqs_map)
 {
-	unsigned int nr_ids = dev_maps->nr_ids;
 	bool active = false;
 	int i, j;
 
-	for (j = -1; j = netif_attrmask_next(j, mask, nr_ids), j < nr_ids;)
-		active |= remove_xps_queue_cpu(dev, dev_maps, j, offset,
-					       count);
+	for (j = 0; j < dev_maps->nr_ids; j++)
+		active |= remove_xps_queue_cpu(dev, dev_maps, j, offset, count);
 	if (!active)
 		reset_xps_maps(dev, dev_maps, is_rxqs_map);
 
-	if (!is_rxqs_map) {
-		for (i = offset + (count - 1); count--; i--) {
+	if (!is_rxqs_map)
+		for (i = offset + (count - 1); count--; i--)
 			netdev_queue_numa_node_write(
-				netdev_get_tx_queue(dev, i),
-				NUMA_NO_NODE);
-		}
-	}
+				netdev_get_tx_queue(dev, i), NUMA_NO_NODE);
 }
 
 static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
 				   u16 count)
 {
-	const unsigned long *possible_mask = NULL;
 	struct xps_dev_maps *dev_maps;
 
 	if (!static_key_false(&xps_needed))
@@ -2543,17 +2537,14 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
 	if (static_key_false(&xps_rxqs_needed)) {
 		dev_maps = xmap_dereference(dev->xps_rxqs_map);
 		if (dev_maps)
-			clean_xps_maps(dev, possible_mask, dev_maps, offset,
-				       count, true);
+			clean_xps_maps(dev, dev_maps, offset, count, true);
 	}
 
 	dev_maps = xmap_dereference(dev->xps_cpus_map);
 	if (!dev_maps)
 		goto out_no_maps;
 
-	if (num_possible_cpus() > 1)
-		possible_mask = cpumask_bits(cpu_possible_mask);
-	clean_xps_maps(dev, possible_mask, dev_maps, offset, count, false);
+	clean_xps_maps(dev, dev_maps, offset, count, false);
 
 out_no_maps:
 	mutex_unlock(&xps_map_mutex);
@@ -2609,8 +2600,8 @@ static struct xps_map *expand_xps_map(struct xps_map *map, int attr_index,
 int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 			  u16 index, bool is_rxqs_map)
 {
-	const unsigned long *online_mask = NULL, *possible_mask = NULL;
 	struct xps_dev_maps *dev_maps, *new_dev_maps = NULL;
+	const unsigned long *online_mask = NULL;
 	bool active = false, copy = false;
 	int i, j, tci, numa_node_id = -2;
 	int maps_sz, num_tc = 1, tc = 0;
@@ -2640,10 +2631,8 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		nr_ids = dev->num_rx_queues;
 	} else {
 		maps_sz = XPS_CPU_DEV_MAPS_SIZE(num_tc);
-		if (num_possible_cpus() > 1) {
+		if (num_possible_cpus() > 1)
 			online_mask = cpumask_bits(cpu_online_mask);
-			possible_mask = cpumask_bits(cpu_possible_mask);
-		}
 		dev_maps = xmap_dereference(dev->xps_cpus_map);
 		nr_ids = nr_cpu_ids;
 	}
@@ -2693,8 +2682,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 			static_key_slow_inc_cpuslocked(&xps_rxqs_needed);
 	}
 
-	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
-	     j < nr_ids;) {
+	for (j = 0; j < nr_ids; j++) {
 		/* copy maps belonging to foreign traffic classes */
 		for (i = tc, tci = j * num_tc; copy && i--; tci++) {
 			/* fill in the new device map from the old device map */
@@ -2749,8 +2737,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	if (!dev_maps)
 		goto out_no_old_maps;
 
-	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
-	     j < nr_ids;) {
+	for (j = 0; j < nr_ids; j++) {
 		for (i = num_tc, tci = j * dev_maps->num_tc; i--; tci++) {
 			map = xmap_dereference(dev_maps->attr_map[tci]);
 			if (!map)
@@ -2784,8 +2771,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		goto out_no_maps;
 
 	/* removes tx-queue from unused CPUs/rx-queues */
-	for (j = -1; j = netif_attrmask_next(j, possible_mask, dev_maps->nr_ids),
-	     j < dev_maps->nr_ids;) {
+	for (j = 0; j < dev_maps->nr_ids; j++) {
 		for (i = tc, tci = j * dev_maps->num_tc; i--; tci++)
 			active |= remove_xps_queue(dev_maps, tci, index);
 		if (!netif_attr_test_mask(j, mask, dev_maps->nr_ids) ||
@@ -2805,8 +2791,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	return 0;
 error:
 	/* remove any maps that we added */
-	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
-	     j < nr_ids;) {
+	for (j = 0; j < nr_ids; j++) {
 		for (i = num_tc, tci = j * num_tc; i--; tci++) {
 			new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
 			map = copy ?
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index e544e5f2467c..6180c35d5108 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1353,7 +1353,7 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	if (!dev_maps || tc >= dev_maps->num_tc)
 		goto out_no_maps;
 
-	for (j = -1; j = netif_attrmask_next(j, NULL, nr_ids), j < nr_ids;) {
+	for (j = 0; j < nr_ids; j++) {
 		int i, tci = j * dev_maps->num_tc + tc;
 		struct xps_map *map;
 
@@ -1457,7 +1457,7 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 	if (!dev_maps || tc >= dev_maps->num_tc)
 		goto out_no_maps;
 
-	for (j = -1; j = netif_attrmask_next(j, NULL, nr_ids), j < nr_ids;) {
+	for (j = 0; j < nr_ids; j++) {
 		int i, tci = j * dev_maps->num_tc + tc;
 		struct xps_map *map;
 
-- 
2.29.2

[PATCH net-next v2 08/12] net: move the xps maps to an array

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:26:33 

Move the xps maps (xps_cpus_map and xps_rxqs_map) to an array in
net_device. That will simplify a lot the code removing the need for lots
of if/else conditionals as the correct map will be available using its
offset in the array.

This should not modify the xps maps behaviour in any way.

Suggested-by: Alexander Duyck <redacted>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 drivers/net/virtio_net.c  |  2 +-
 include/linux/netdevice.h | 17 +++++----
 net/core/dev.c            | 73 +++++++++++++++++----------------------
 net/core/net-sysfs.c      |  6 ++--
 4 files changed, 46 insertions(+), 52 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index ba8e63792549..1c98ef44c6a1 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1980,7 +1980,7 @@ static void virtnet_set_affinity(struct virtnet_info *vi)
 		}
 		virtqueue_set_affinity(vi->rq[i].vq, mask);
 		virtqueue_set_affinity(vi->sq[i].vq, mask);
-		__netif_set_xps_queue(vi->dev, cpumask_bits(mask), i, false);
+		__netif_set_xps_queue(vi->dev, cpumask_bits(mask), i, XPS_CPUS);
 		cpumask_clear(mask);
 	}
 
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 40683b6eee54..e868ce03db89 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -762,6 +762,13 @@ struct rx_queue_attribute {
 			 const char *buf, size_t len);
 };
 
+/* XPS map type and offset of the xps map within net_device->xps_maps[]. */
+enum xps_map_type {
+	XPS_CPUS = 0,
+	XPS_RXQS,
+	XPS_MAPS_MAX,
+};
+
 #ifdef CONFIG_XPS
 /*
  * This structure holds an XPS map which can be of variable length.  The
@@ -1770,8 +1777,7 @@ enum netdev_priv_flags {
  *	@tx_queue_len:		Max frames per queue allowed
  *	@tx_global_lock: 	XXX: need comments on this one
  *	@xdp_bulkq:		XDP device bulk queue
- *	@xps_cpus_map:		all CPUs map for XPS device
- *	@xps_rxqs_map:		all RXQs map for XPS device
+ *	@xps_maps:		all CPUs/RXQs maps for XPS device
  *
  *	@xps_maps:	XXX: need comments on this one
  *	@miniq_egress:		clsact qdisc specific data for
@@ -2064,8 +2070,7 @@ struct net_device {
 	struct xdp_dev_bulk_queue __percpu *xdp_bulkq;
 
 #ifdef CONFIG_XPS
-	struct xps_dev_maps __rcu *xps_cpus_map;
-	struct xps_dev_maps __rcu *xps_rxqs_map;
+	struct xps_dev_maps __rcu *xps_maps[XPS_MAPS_MAX];
 #endif
 #ifdef CONFIG_NET_CLS_ACT
 	struct mini_Qdisc __rcu	*miniq_egress;
@@ -3669,7 +3674,7 @@ static inline void netif_wake_subqueue(struct net_device *dev, u16 queue_index)
 int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
 			u16 index);
 int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
-			  u16 index, bool is_rxqs_map);
+			  u16 index, enum xps_map_type type);
 
 /**
  *	netif_attr_test_mask - Test a CPU or Rx queue set in a mask
@@ -3764,7 +3769,7 @@ static inline int netif_set_xps_queue(struct net_device *dev,
 
 static inline int __netif_set_xps_queue(struct net_device *dev,
 					const unsigned long *mask,
-					u16 index, bool is_rxqs_map)
+					u16 index, enum xps_map_type type)
 {
 	return 0;
 }
diff --git a/net/core/dev.c b/net/core/dev.c
index d0c07ccea2e5..6a2f827beca1 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2493,31 +2493,34 @@ static bool remove_xps_queue_cpu(struct net_device *dev,
 
 static void reset_xps_maps(struct net_device *dev,
 			   struct xps_dev_maps *dev_maps,
-			   bool is_rxqs_map)
+			   enum xps_map_type type)
 {
-	if (is_rxqs_map) {
-		static_key_slow_dec_cpuslocked(&xps_rxqs_needed);
-		RCU_INIT_POINTER(dev->xps_rxqs_map, NULL);
-	} else {
-		RCU_INIT_POINTER(dev->xps_cpus_map, NULL);
-	}
 	static_key_slow_dec_cpuslocked(&xps_needed);
+	if (type == XPS_RXQS)
+		static_key_slow_dec_cpuslocked(&xps_rxqs_needed);
+
+	RCU_INIT_POINTER(dev->xps_maps[type], NULL);
+
 	kfree_rcu(dev_maps, rcu);
 }
 
-static void clean_xps_maps(struct net_device *dev,
-			   struct xps_dev_maps *dev_maps, u16 offset, u16 count,
-			   bool is_rxqs_map)
+static void clean_xps_maps(struct net_device *dev, enum xps_map_type type,
+			   u16 offset, u16 count)
 {
+	struct xps_dev_maps *dev_maps;
 	bool active = false;
 	int i, j;
 
+	dev_maps = xmap_dereference(dev->xps_maps[type]);
+	if (!dev_maps)
+		return;
+
 	for (j = 0; j < dev_maps->nr_ids; j++)
 		active |= remove_xps_queue_cpu(dev, dev_maps, j, offset, count);
 	if (!active)
-		reset_xps_maps(dev, dev_maps, is_rxqs_map);
+		reset_xps_maps(dev, dev_maps, type);
 
-	if (!is_rxqs_map)
+	if (type == XPS_CPUS)
 		for (i = offset + (count - 1); count--; i--)
 			netdev_queue_numa_node_write(
 				netdev_get_tx_queue(dev, i), NUMA_NO_NODE);
@@ -2526,27 +2529,17 @@ static void clean_xps_maps(struct net_device *dev,
 static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
 				   u16 count)
 {
-	struct xps_dev_maps *dev_maps;
-
 	if (!static_key_false(&xps_needed))
 		return;
 
 	cpus_read_lock();
 	mutex_lock(&xps_map_mutex);
 
-	if (static_key_false(&xps_rxqs_needed)) {
-		dev_maps = xmap_dereference(dev->xps_rxqs_map);
-		if (dev_maps)
-			clean_xps_maps(dev, dev_maps, offset, count, true);
-	}
-
-	dev_maps = xmap_dereference(dev->xps_cpus_map);
-	if (!dev_maps)
-		goto out_no_maps;
+	if (static_key_false(&xps_rxqs_needed))
+		clean_xps_maps(dev, XPS_RXQS, offset, count);
 
-	clean_xps_maps(dev, dev_maps, offset, count, false);
+	clean_xps_maps(dev, XPS_CPUS, offset, count);
 
-out_no_maps:
 	mutex_unlock(&xps_map_mutex);
 	cpus_read_unlock();
 }
@@ -2598,7 +2591,7 @@ static struct xps_map *expand_xps_map(struct xps_map *map, int attr_index,
 
 /* Must be called under rtnl_lock and cpus_read_lock */
 int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
-			  u16 index, bool is_rxqs_map)
+			  u16 index, enum xps_map_type type)
 {
 	struct xps_dev_maps *dev_maps, *new_dev_maps = NULL;
 	const unsigned long *online_mask = NULL;
@@ -2625,15 +2618,15 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	}
 
 	mutex_lock(&xps_map_mutex);
-	if (is_rxqs_map) {
+
+	dev_maps = xmap_dereference(dev->xps_maps[type]);
+	if (type == XPS_RXQS) {
 		maps_sz = XPS_RXQ_DEV_MAPS_SIZE(num_tc, dev->num_rx_queues);
-		dev_maps = xmap_dereference(dev->xps_rxqs_map);
 		nr_ids = dev->num_rx_queues;
 	} else {
 		maps_sz = XPS_CPU_DEV_MAPS_SIZE(num_tc);
 		if (num_possible_cpus() > 1)
 			online_mask = cpumask_bits(cpu_online_mask);
-		dev_maps = xmap_dereference(dev->xps_cpus_map);
 		nr_ids = nr_cpu_ids;
 	}
 
@@ -2665,7 +2658,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		tci = j * num_tc + tc;
 		map = copy ? xmap_dereference(dev_maps->attr_map[tci]) : NULL;
 
-		map = expand_xps_map(map, j, index, is_rxqs_map);
+		map = expand_xps_map(map, j, index, type == XPS_RXQS);
 		if (!map)
 			goto error;
 
@@ -2678,7 +2671,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	if (!dev_maps) {
 		/* Increment static keys at most once per type */
 		static_key_slow_inc_cpuslocked(&xps_needed);
-		if (is_rxqs_map)
+		if (type == XPS_RXQS)
 			static_key_slow_inc_cpuslocked(&xps_rxqs_needed);
 	}
 
@@ -2707,7 +2700,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 			if (pos == map->len)
 				map->queues[map->len++] = index;
 #ifdef CONFIG_NUMA
-			if (!is_rxqs_map) {
+			if (type == XPS_CPUS) {
 				if (numa_node_id == -2)
 					numa_node_id = cpu_to_node(j);
 				else if (numa_node_id != cpu_to_node(j))
@@ -2728,10 +2721,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 		}
 	}
 
-	if (is_rxqs_map)
-		rcu_assign_pointer(dev->xps_rxqs_map, new_dev_maps);
-	else
-		rcu_assign_pointer(dev->xps_cpus_map, new_dev_maps);
+	rcu_assign_pointer(dev->xps_maps[type], new_dev_maps);
 
 	/* Cleanup old maps */
 	if (!dev_maps)
@@ -2760,12 +2750,11 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	active = true;
 
 out_no_new_maps:
-	if (!is_rxqs_map) {
+	if (type == XPS_CPUS)
 		/* update Tx queue numa node */
 		netdev_queue_numa_node_write(netdev_get_tx_queue(dev, index),
 					     (numa_node_id >= 0) ?
 					     numa_node_id : NUMA_NO_NODE);
-	}
 
 	if (!dev_maps)
 		goto out_no_maps;
@@ -2783,7 +2772,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 
 	/* free map if not active */
 	if (!active)
-		reset_xps_maps(dev, dev_maps, is_rxqs_map);
+		reset_xps_maps(dev, dev_maps, type);
 
 out_no_maps:
 	mutex_unlock(&xps_map_mutex);
@@ -2815,7 +2804,7 @@ int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
 	int ret;
 
 	cpus_read_lock();
-	ret =  __netif_set_xps_queue(dev, cpumask_bits(mask), index, false);
+	ret =  __netif_set_xps_queue(dev, cpumask_bits(mask), index, XPS_CPUS);
 	cpus_read_unlock();
 
 	return ret;
@@ -3965,7 +3954,7 @@ static int get_xps_queue(struct net_device *dev, struct net_device *sb_dev,
 	if (!static_key_false(&xps_rxqs_needed))
 		goto get_cpus_map;
 
-	dev_maps = rcu_dereference(sb_dev->xps_rxqs_map);
+	dev_maps = rcu_dereference(sb_dev->xps_maps[XPS_RXQS]);
 	if (dev_maps) {
 		int tci = sk_rx_queue_get(sk);
 
@@ -3976,7 +3965,7 @@ static int get_xps_queue(struct net_device *dev, struct net_device *sb_dev,
 
 get_cpus_map:
 	if (queue_index < 0) {
-		dev_maps = rcu_dereference(sb_dev->xps_cpus_map);
+		dev_maps = rcu_dereference(sb_dev->xps_maps[XPS_CPUS]);
 		if (dev_maps) {
 			unsigned int tci = skb->sender_cpu - 1;
 
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 6180c35d5108..c2276b589cfb 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1341,7 +1341,7 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	}
 
 	rcu_read_lock();
-	dev_maps = rcu_dereference(dev->xps_cpus_map);
+	dev_maps = rcu_dereference(dev->xps_maps[XPS_CPUS]);
 	nr_ids = dev_maps ? dev_maps->nr_ids : nr_cpu_ids;
 
 	mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
@@ -1445,7 +1445,7 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 	}
 
 	rcu_read_lock();
-	dev_maps = rcu_dereference(dev->xps_rxqs_map);
+	dev_maps = rcu_dereference(dev->xps_maps[XPS_RXQS]);
 	nr_ids = dev_maps ? dev_maps->nr_ids : dev->num_rx_queues;
 
 	mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
@@ -1519,7 +1519,7 @@ static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf,
 	}
 
 	cpus_read_lock();
-	err = __netif_set_xps_queue(dev, mask, index, true);
+	err = __netif_set_xps_queue(dev, mask, index, XPS_RXQS);
 	cpus_read_unlock();
 
 	rtnl_unlock();
-- 
2.29.2

[PATCH net-next v2 11/12] net: improve queue removal readability in __netif_set_xps_queue

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:26:58 

Improve the readability of the loop removing tx-queue from unused
CPUs/rx-queues in __netif_set_xps_queue. The change should only be
cosmetic.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/dev.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 9b91e0d0895c..7c3ac6736bb6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2766,13 +2766,16 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 
 	/* removes tx-queue from unused CPUs/rx-queues */
 	for (j = 0; j < dev_maps->nr_ids; j++) {
-		for (i = tc, tci = j * dev_maps->num_tc; i--; tci++)
-			active |= remove_xps_queue(dev_maps, tci, index);
-		if (!netif_attr_test_mask(j, mask, dev_maps->nr_ids) ||
-		    !netif_attr_test_online(j, online_mask, dev_maps->nr_ids))
-			active |= remove_xps_queue(dev_maps, tci, index);
-		for (i = dev_maps->num_tc - tc, tci++; --i; tci++)
+		tci = j * dev_maps->num_tc;
+
+		for (i = 0; i < dev_maps->num_tc; i++, tci++) {
+			if (i == tc &&
+			    netif_attr_test_mask(j, mask, dev_maps->nr_ids) &&
+			    netif_attr_test_online(j, online_mask, dev_maps->nr_ids))
+				continue;
+
 			active |= remove_xps_queue(dev_maps, tci, index);
+		}
 	}
 
 	/* free map if not active */
-- 
2.29.2

[PATCH net-next v2 04/12] net: embed num_tc in the xps maps

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:26:58 

The xps cpus/rxqs map is accessed using dev->num_tc, which is used when
allocating the map. But later updates of dev->num_tc can lead to having
a mismatch between the maps and how they're accessed. In such cases the
map values do not make any sense and out of bound accesses can occur
(that can be easily seen using KASAN).

This patch aims at fixing this by embedding num_tc into the maps, using
the value at the time the map is created. This brings two improvements:
- The maps can be accessed using the embedded num_tc, so we know for
  sure we won't have out of bound accesses.
- Checks can be made before accessing the maps so we know the values
  retrieved will make sense.

We also update __netif_set_xps_queue to conditionally copy old maps from
dev_maps in the new one only if the number of traffic classes from both
maps match.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 include/linux/netdevice.h |  6 ++++
 net/core/dev.c            | 63 +++++++++++++++++++++++++--------------
 net/core/net-sysfs.c      | 45 +++++++++++-----------------
 3 files changed, 64 insertions(+), 50 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e9e7ada07ea1..d7d3c646d40d 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -779,9 +779,15 @@ struct xps_map {
 
 /*
  * This structure holds all XPS maps for device.  Maps are indexed by CPU.
+ *
+ * We keep track of the number of traffic classes used when the struct is
+ * allocated, in num_tc. This will be used to navigate the maps, to ensure we're
+ * not crossing its upper bound, as the original dev->num_tc can be updated in
+ * the meantime.
  */
 struct xps_dev_maps {
 	struct rcu_head rcu;
+	s16 num_tc;
 	struct xps_map __rcu *attr_map[]; /* Either CPUs map or RXQs map */
 };
 
diff --git a/net/core/dev.c b/net/core/dev.c
index 21d74d30f5d7..7c5e2c614723 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2473,7 +2473,7 @@ static bool remove_xps_queue_cpu(struct net_device *dev,
 				 struct xps_dev_maps *dev_maps,
 				 int cpu, u16 offset, u16 count)
 {
-	int num_tc = dev->num_tc ? : 1;
+	int num_tc = dev_maps->num_tc;
 	bool active = false;
 	int tci;
 
@@ -2616,10 +2616,10 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 {
 	const unsigned long *online_mask = NULL, *possible_mask = NULL;
 	struct xps_dev_maps *dev_maps, *new_dev_maps = NULL;
+	bool active = false, copy = false;
 	int i, j, tci, numa_node_id = -2;
 	int maps_sz, num_tc = 1, tc = 0;
 	struct xps_map *map, *new_map;
-	bool active = false;
 	unsigned int nr_ids;
 
 	if (dev->num_tc) {
@@ -2654,19 +2654,29 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	if (maps_sz < L1_CACHE_BYTES)
 		maps_sz = L1_CACHE_BYTES;
 
+	/* The old dev_maps could be larger or smaller than the one we're
+	 * setting up now, as dev->num_tc could have been updated in between. We
+	 * could try to be smart, but let's be safe instead and only copy
+	 * foreign traffic classes if the two map sizes match.
+	 */
+	if (dev_maps && dev_maps->num_tc == num_tc)
+		copy = true;
+
 	/* allocate memory for queue storage */
 	for (j = -1; j = netif_attrmask_next_and(j, online_mask, mask, nr_ids),
 	     j < nr_ids;) {
-		if (!new_dev_maps)
-			new_dev_maps = kzalloc(maps_sz, GFP_KERNEL);
 		if (!new_dev_maps) {
-			mutex_unlock(&xps_map_mutex);
-			return -ENOMEM;
+			new_dev_maps = kzalloc(maps_sz, GFP_KERNEL);
+			if (!new_dev_maps) {
+				mutex_unlock(&xps_map_mutex);
+				return -ENOMEM;
+			}
+
+			new_dev_maps->num_tc = num_tc;
 		}
 
 		tci = j * num_tc + tc;
-		map = dev_maps ? xmap_dereference(dev_maps->attr_map[tci]) :
-				 NULL;
+		map = copy ? xmap_dereference(dev_maps->attr_map[tci]) : NULL;
 
 		map = expand_xps_map(map, j, index, is_rxqs_map);
 		if (!map)
@@ -2688,7 +2698,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
 	     j < nr_ids;) {
 		/* copy maps belonging to foreign traffic classes */
-		for (i = tc, tci = j * num_tc; dev_maps && i--; tci++) {
+		for (i = tc, tci = j * num_tc; copy && i--; tci++) {
 			/* fill in the new device map from the old device map */
 			map = xmap_dereference(dev_maps->attr_map[tci]);
 			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
@@ -2718,14 +2728,14 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 					numa_node_id = -1;
 			}
 #endif
-		} else if (dev_maps) {
+		} else if (copy) {
 			/* fill in the new device map from the old device map */
 			map = xmap_dereference(dev_maps->attr_map[tci]);
 			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
 		}
 
 		/* copy maps belonging to foreign traffic classes */
-		for (i = num_tc - tc, tci++; dev_maps && --i; tci++) {
+		for (i = num_tc - tc, tci++; copy && --i; tci++) {
 			/* fill in the new device map from the old device map */
 			map = xmap_dereference(dev_maps->attr_map[tci]);
 			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
@@ -2743,11 +2753,18 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 
 	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
 	     j < nr_ids;) {
-		for (i = num_tc, tci = j * num_tc; i--; tci++) {
-			new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
+		for (i = num_tc, tci = j * dev_maps->num_tc; i--; tci++) {
 			map = xmap_dereference(dev_maps->attr_map[tci]);
-			if (map && map != new_map)
-				kfree_rcu(map, rcu);
+			if (!map)
+				continue;
+
+			if (copy) {
+				new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
+				if (map == new_map)
+					continue;
+			}
+
+			kfree_rcu(map, rcu);
 		}
 	}
 
@@ -2771,12 +2788,12 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	/* removes tx-queue from unused CPUs/rx-queues */
 	for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
 	     j < nr_ids;) {
-		for (i = tc, tci = j * num_tc; i--; tci++)
+		for (i = tc, tci = j * dev_maps->num_tc; i--; tci++)
 			active |= remove_xps_queue(dev_maps, tci, index);
 		if (!netif_attr_test_mask(j, mask, nr_ids) ||
 		    !netif_attr_test_online(j, online_mask, nr_ids))
 			active |= remove_xps_queue(dev_maps, tci, index);
-		for (i = num_tc - tc, tci++; --i; tci++)
+		for (i = dev_maps->num_tc - tc, tci++; --i; tci++)
 			active |= remove_xps_queue(dev_maps, tci, index);
 	}
 
@@ -2794,7 +2811,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	     j < nr_ids;) {
 		for (i = num_tc, tci = j * num_tc; i--; tci++) {
 			new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
-			map = dev_maps ?
+			map = copy ?
 			      xmap_dereference(dev_maps->attr_map[tci]) :
 			      NULL;
 			if (new_map && new_map != map)
@@ -3926,13 +3943,15 @@ sch_handle_egress(struct sk_buff *skb, int *ret, struct net_device *dev)
 static int __get_xps_queue_idx(struct net_device *dev, struct sk_buff *skb,
 			       struct xps_dev_maps *dev_maps, unsigned int tci)
 {
+	int tc = netdev_get_prio_tc_map(dev, skb->priority);
 	struct xps_map *map;
 	int queue_index = -1;
 
-	if (dev->num_tc) {
-		tci *= dev->num_tc;
-		tci += netdev_get_prio_tc_map(dev, skb->priority);
-	}
+	if (tc >= dev_maps->num_tc)
+		return queue_index;
+
+	tci *= dev_maps->num_tc;
+	tci += tc;
 
 	map = rcu_dereference(dev_maps->attr_map[tci]);
 	if (map) {
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 3915b1826814..c1d4d3e712a9 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1317,9 +1317,9 @@ static const struct attribute_group dql_group = {
 static ssize_t xps_cpus_show(struct netdev_queue *queue,
 			     char *buf)
 {
-	int j, len, ret, num_tc = 1, tc = 0;
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
+	int j, len, ret, tc = 0;
 	unsigned long *mask;
 	unsigned int index;
 
@@ -1331,22 +1331,13 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	if (!rtnl_trylock())
 		return restart_syscall();
 
-	if (dev->num_tc) {
-		/* Do not allow XPS on subordinate device directly */
-		num_tc = dev->num_tc;
-		if (num_tc < 0) {
-			ret = -EINVAL;
-			goto err_rtnl_unlock;
-		}
-
-		/* If queue belongs to subordinate dev use its map */
-		dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
+	/* If queue belongs to subordinate dev use its map */
+	dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
 
-		tc = netdev_txq_to_tc(dev, index);
-		if (tc < 0) {
-			ret = -EINVAL;
-			goto err_rtnl_unlock;
-		}
+	tc = netdev_txq_to_tc(dev, index);
+	if (tc < 0) {
+		ret = -EINVAL;
+		goto err_rtnl_unlock;
 	}
 
 	mask = bitmap_zalloc(nr_cpu_ids, GFP_KERNEL);
@@ -1357,12 +1348,12 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 	rcu_read_lock();
 	dev_maps = rcu_dereference(dev->xps_cpus_map);
-	if (!dev_maps)
+	if (!dev_maps || tc >= dev_maps->num_tc)
 		goto out_no_maps;
 
 	for (j = -1; j = netif_attrmask_next(j, NULL, nr_cpu_ids),
 	     j < nr_cpu_ids;) {
-		int i, tci = j * num_tc + tc;
+		int i, tci = j * dev_maps->num_tc + tc;
 		struct xps_map *map;
 
 		map = rcu_dereference(dev_maps->attr_map[tci]);
@@ -1433,9 +1424,9 @@ static struct netdev_queue_attribute xps_cpus_attribute __ro_after_init
 
 static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 {
-	int j, len, ret, num_tc = 1, tc = 0;
 	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
+	int j, len, ret, tc = 0;
 	unsigned long *mask;
 	unsigned int index;
 
@@ -1444,14 +1435,12 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 	if (!rtnl_trylock())
 		return restart_syscall();
 
-	if (dev->num_tc) {
-		num_tc = dev->num_tc;
-		tc = netdev_txq_to_tc(dev, index);
-		if (tc < 0) {
-			ret = -EINVAL;
-			goto err_rtnl_unlock;
-		}
+	tc = netdev_txq_to_tc(dev, index);
+	if (tc < 0) {
+		ret = -EINVAL;
+		goto err_rtnl_unlock;
 	}
+
 	mask = bitmap_zalloc(dev->num_rx_queues, GFP_KERNEL);
 	if (!mask) {
 		ret = -ENOMEM;
@@ -1460,12 +1449,12 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 
 	rcu_read_lock();
 	dev_maps = rcu_dereference(dev->xps_rxqs_map);
-	if (!dev_maps)
+	if (!dev_maps || tc >= dev_maps->num_tc)
 		goto out_no_maps;
 
 	for (j = -1; j = netif_attrmask_next(j, NULL, dev->num_rx_queues),
 	     j < dev->num_rx_queues;) {
-		int i, tci = j * num_tc + tc;
+		int i, tci = j * dev_maps->num_tc + tc;
 		struct xps_map *map;
 
 		map = rcu_dereference(dev_maps->attr_map[tci]);
-- 
2.29.2

[PATCH net-next v2 10/12] net: add an helper to copy xps maps to the new dev_maps

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:27:27 

This patch adds an helper, xps_copy_dev_maps, to copy maps from dev_maps
to new_dev_maps at a given index. The logic should be the same, with an
improved code readability and maintenance.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/dev.c | 45 +++++++++++++++++++++++++--------------------
 1 file changed, 25 insertions(+), 20 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 6a2f827beca1..9b91e0d0895c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2589,6 +2589,25 @@ static struct xps_map *expand_xps_map(struct xps_map *map, int attr_index,
 	return new_map;
 }
 
+/* Copy xps maps at a given index */
+static void xps_copy_dev_maps(struct xps_dev_maps *dev_maps,
+			      struct xps_dev_maps *new_dev_maps, int index,
+			      int tc, bool skip_tc)
+{
+	int i, tci = index * dev_maps->num_tc;
+	struct xps_map *map;
+
+	/* copy maps belonging to foreign traffic classes */
+	for (i = 0; i < dev_maps->num_tc; i++, tci++) {
+		if (i == tc && skip_tc)
+			continue;
+
+		/* fill in the new device map from the old device map */
+		map = xmap_dereference(dev_maps->attr_map[tci]);
+		RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
+	}
+}
+
 /* Must be called under rtnl_lock and cpus_read_lock */
 int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 			  u16 index, enum xps_map_type type)
@@ -2676,23 +2695,16 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 	}
 
 	for (j = 0; j < nr_ids; j++) {
-		/* copy maps belonging to foreign traffic classes */
-		for (i = tc, tci = j * num_tc; copy && i--; tci++) {
-			/* fill in the new device map from the old device map */
-			map = xmap_dereference(dev_maps->attr_map[tci]);
-			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
-		}
+		bool skip_tc = false;
 
-		/* We need to explicitly update tci as prevous loop
-		 * could break out early if dev_maps is NULL.
-		 */
 		tci = j * num_tc + tc;
-
 		if (netif_attr_test_mask(j, mask, nr_ids) &&
 		    netif_attr_test_online(j, online_mask, nr_ids)) {
 			/* add tx-queue to CPU/rx-queue maps */
 			int pos = 0;
 
+			skip_tc = true;
+
 			map = xmap_dereference(new_dev_maps->attr_map[tci]);
 			while ((pos < map->len) && (map->queues[pos] != index))
 				pos++;
@@ -2707,18 +2719,11 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
 					numa_node_id = -1;
 			}
 #endif
-		} else if (copy) {
-			/* fill in the new device map from the old device map */
-			map = xmap_dereference(dev_maps->attr_map[tci]);
-			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
 		}
 
-		/* copy maps belonging to foreign traffic classes */
-		for (i = num_tc - tc, tci++; copy && --i; tci++) {
-			/* fill in the new device map from the old device map */
-			map = xmap_dereference(dev_maps->attr_map[tci]);
-			RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
-		}
+		if (copy)
+			xps_copy_dev_maps(dev_maps, new_dev_maps, j, tc,
+					  skip_tc);
 	}
 
 	rcu_assign_pointer(dev->xps_maps[type], new_dev_maps);
-- 
2.29.2

[PATCH net-next v2 12/12] net-sysfs: move the xps cpus/rxqs retrieval in a common function

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-08 17:28:24 

Most of the xps_cpus_show and xps_rxqs_show functions share the same
logic. Having it in two different functions does not help maintenance.
This patch moves their common logic into a new function, xps_queue_show,
to improve this.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/net-sysfs.c | 98 ++++++++++++++------------------------------
 1 file changed, 31 insertions(+), 67 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 6ce5772e799e..984c15248483 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1314,35 +1314,31 @@ static const struct attribute_group dql_group = {
 #endif /* CONFIG_BQL */
 
 #ifdef CONFIG_XPS
-static ssize_t xps_cpus_show(struct netdev_queue *queue,
-			     char *buf)
+static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
+			      char *buf, enum xps_map_type type)
 {
-	struct net_device *dev = queue->dev;
 	struct xps_dev_maps *dev_maps;
-	unsigned int index, nr_ids;
-	int j, len, ret, tc = 0;
 	unsigned long *mask;
-
-	if (!netif_is_multiqueue(dev))
-		return -ENOENT;
-
-	index = get_netdev_queue_index(queue);
-
-	/* If queue belongs to subordinate dev use its map */
-	dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
+	unsigned int nr_ids;
+	int j, len, tc = 0;
 
 	tc = netdev_txq_to_tc(dev, index);
 	if (tc < 0)
 		return -EINVAL;
 
 	rcu_read_lock();
-	dev_maps = rcu_dereference(dev->xps_maps[XPS_CPUS]);
-	nr_ids = dev_maps ? dev_maps->nr_ids : nr_cpu_ids;
+	dev_maps = rcu_dereference(dev->xps_maps[type]);
+
+	/* Default to nr_cpu_ids/dev->num_rx_queues and do not just return 0
+	 * when dev_maps hasn't been allocated yet, to be backward compatible.
+	 */
+	nr_ids = dev_maps ? dev_maps->nr_ids :
+		 (type == XPS_CPUS ? nr_cpu_ids : dev->num_rx_queues);
 
 	mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
 	if (!mask) {
-		ret = -ENOMEM;
-		goto err_rcu_unlock;
+		rcu_read_unlock();
+		return -ENOMEM;
 	}
 
 	if (!dev_maps || tc >= dev_maps->num_tc)
@@ -1368,11 +1364,24 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 
 	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
 	bitmap_free(mask);
+
 	return len < PAGE_SIZE ? len : -EINVAL;
+}
 
-err_rcu_unlock:
-	rcu_read_unlock();
-	return ret;
+static ssize_t xps_cpus_show(struct netdev_queue *queue, char *buf)
+{
+	struct net_device *dev = queue->dev;
+	unsigned int index;
+
+	if (!netif_is_multiqueue(dev))
+		return -ENOENT;
+
+	index = get_netdev_queue_index(queue);
+
+	/* If queue belongs to subordinate dev use its map */
+	dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
+
+	return xps_queue_show(dev, index, buf, XPS_CPUS);
 }
 
 static ssize_t xps_cpus_store(struct netdev_queue *queue,
@@ -1419,56 +1428,11 @@ static struct netdev_queue_attribute xps_cpus_attribute __ro_after_init
 static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 {
 	struct net_device *dev = queue->dev;
-	struct xps_dev_maps *dev_maps;
-	unsigned int index, nr_ids;
-	int j, len, ret, tc = 0;
-	unsigned long *mask;
+	unsigned int index;
 
 	index = get_netdev_queue_index(queue);
 
-	tc = netdev_txq_to_tc(dev, index);
-	if (tc < 0)
-		return -EINVAL;
-
-	rcu_read_lock();
-	dev_maps = rcu_dereference(dev->xps_maps[XPS_RXQS]);
-	nr_ids = dev_maps ? dev_maps->nr_ids : dev->num_rx_queues;
-
-	mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
-	if (!mask) {
-		ret = -ENOMEM;
-		goto err_rcu_unlock;
-	}
-
-	if (!dev_maps || tc >= dev_maps->num_tc)
-		goto out_no_maps;
-
-	for (j = 0; j < nr_ids; j++) {
-		int i, tci = j * dev_maps->num_tc + tc;
-		struct xps_map *map;
-
-		map = rcu_dereference(dev_maps->attr_map[tci]);
-		if (!map)
-			continue;
-
-		for (i = map->len; i--;) {
-			if (map->queues[i] == index) {
-				set_bit(j, mask);
-				break;
-			}
-		}
-	}
-out_no_maps:
-	rcu_read_unlock();
-
-	len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
-	bitmap_free(mask);
-
-	return len < PAGE_SIZE ? len : -EINVAL;
-
-err_rcu_unlock:
-	rcu_read_unlock();
-	return ret;
+	return xps_queue_show(dev, index, buf, XPS_RXQS);
 }
 
 static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf,
-- 
2.29.2

Re: [PATCH net-next v2 07/12] net: remove the xps possible_mask

From: Alexander Duyck <hidden>
Date: 2021-02-08 21:46:17 

On Mon, Feb 8, 2021 at 9:19 AM Antoine Tenart [off-list ref] wrote:
quoted hunk
Remove the xps possible_mask. It was an optimization but we can just
loop from 0 to nr_ids now that it is embedded in the xps dev_maps. That
simplifies the code a bit.

Suggested-by: Alexander Duyck <redacted>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/dev.c       | 43 ++++++++++++++-----------------------------
 net/core/net-sysfs.c |  4 ++--
 2 files changed, 16 insertions(+), 31 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index abbb2ae6b3ed..d0c07ccea2e5 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2505,33 +2505,27 @@ static void reset_xps_maps(struct net_device *dev,
        kfree_rcu(dev_maps, rcu);
 }

-static void clean_xps_maps(struct net_device *dev, const unsigned long *mask,
+static void clean_xps_maps(struct net_device *dev,
                           struct xps_dev_maps *dev_maps, u16 offset, u16 count,
                           bool is_rxqs_map)
 {
-       unsigned int nr_ids = dev_maps->nr_ids;
        bool active = false;
        int i, j;

-       for (j = -1; j = netif_attrmask_next(j, mask, nr_ids), j < nr_ids;)
-               active |= remove_xps_queue_cpu(dev, dev_maps, j, offset,
-                                              count);
+       for (j = 0; j < dev_maps->nr_ids; j++)
+               active |= remove_xps_queue_cpu(dev, dev_maps, j, offset, count);
        if (!active)
                reset_xps_maps(dev, dev_maps, is_rxqs_map);

-       if (!is_rxqs_map) {
-               for (i = offset + (count - 1); count--; i--) {
+       if (!is_rxqs_map)
+               for (i = offset + (count - 1); count--; i--)
                        netdev_queue_numa_node_write(
-                               netdev_get_tx_queue(dev, i),
-                               NUMA_NO_NODE);
-               }
-       }
+                               netdev_get_tx_queue(dev, i), NUMA_NO_NODE);
 }
This violates the coding-style guide for the kernel. The if statement
should still have braces as the for loop and
netdev_queue_numa_node_write are more than a single statement. I'd be
curious to see if checkpatch also complains about this because it
probably should.

For reference see the end of section 3.0 in
Documentation/process/coding-style.rst.

Other than that the rest of the patch seemed to be fine.

Re: [PATCH net-next v2 09/12] net-sysfs: remove the rtnl lock when accessing the xps maps

From: Alexander Duyck <hidden>
Date: 2021-02-08 22:22:17 

On Mon, Feb 8, 2021 at 9:19 AM Antoine Tenart [off-list ref] wrote:
quoted hunk
Now that nr_ids and num_tc are stored in the xps dev_maps, which are RCU
protected, we do not have the need to protect the xps_cpus_show and
xps_rxqs_show functions with the rtnl lock.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/net-sysfs.c | 26 ++++----------------------
 1 file changed, 4 insertions(+), 22 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index c2276b589cfb..6ce5772e799e 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1328,17 +1328,12 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,

        index = get_netdev_queue_index(queue);

-       if (!rtnl_trylock())
-               return restart_syscall();
-
        /* If queue belongs to subordinate dev use its map */
        dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;

        tc = netdev_txq_to_tc(dev, index);
-       if (tc < 0) {
-               ret = -EINVAL;
-               goto err_rtnl_unlock;
-       }
+       if (tc < 0)
+               return -EINVAL;

        rcu_read_lock();
        dev_maps = rcu_dereference(dev->xps_maps[XPS_CPUS]);
So I think we hit a snag here. The sb_dev pointer is protected by the
rtnl_lock. So I don't think we can release the rtnl_lock until after
we are done with the dev pointer.

Also I am not sure it is safe to use netdev_txq_to_tc without holding
the lock. I don't know if we ever went through and guaranteed that it
will always work if the lock isn't held since in theory the device
could reprogram all the map values out from under us.

Odds are we should probably fix traffic_class_show as I suspect it
probably also needs to be holding the rtnl_lock to prevent any
possible races. I'll submit a patch for that.
quoted hunk
@@ -1371,16 +1366,12 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 out_no_maps:
        rcu_read_unlock();

-       rtnl_unlock();
-
        len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
        bitmap_free(mask);
        return len < PAGE_SIZE ? len : -EINVAL;

 err_rcu_unlock:
        rcu_read_unlock();
-err_rtnl_unlock:
-       rtnl_unlock();
        return ret;
 }

@@ -1435,14 +1426,9 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)

        index = get_netdev_queue_index(queue);

-       if (!rtnl_trylock())
-               return restart_syscall();
-
        tc = netdev_txq_to_tc(dev, index);
-       if (tc < 0) {
-               ret = -EINVAL;
-               goto err_rtnl_unlock;
-       }
+       if (tc < 0)
+               return -EINVAL;

        rcu_read_lock();
        dev_maps = rcu_dereference(dev->xps_maps[XPS_RXQS]);
@@ -1475,8 +1461,6 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
 out_no_maps:
        rcu_read_unlock();

-       rtnl_unlock();
-
        len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
        bitmap_free(mask);

@@ -1484,8 +1468,6 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)

 err_rcu_unlock:
        rcu_read_unlock();
-err_rtnl_unlock:
-       rtnl_unlock();
        return ret;
 }

--
2.29.2

Re: [PATCH net-next v2 12/12] net-sysfs: move the xps cpus/rxqs retrieval in a common function

From: Alexander Duyck <hidden>
Date: 2021-02-08 22:46:42 

On Mon, Feb 8, 2021 at 9:19 AM Antoine Tenart [off-list ref] wrote:
quoted hunk
Most of the xps_cpus_show and xps_rxqs_show functions share the same
logic. Having it in two different functions does not help maintenance.
This patch moves their common logic into a new function, xps_queue_show,
to improve this.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
 net/core/net-sysfs.c | 98 ++++++++++++++------------------------------
 1 file changed, 31 insertions(+), 67 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 6ce5772e799e..984c15248483 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1314,35 +1314,31 @@ static const struct attribute_group dql_group = {
 #endif /* CONFIG_BQL */

 #ifdef CONFIG_XPS
-static ssize_t xps_cpus_show(struct netdev_queue *queue,
-                            char *buf)
+static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
+                             char *buf, enum xps_map_type type)
 {
-       struct net_device *dev = queue->dev;
        struct xps_dev_maps *dev_maps;
-       unsigned int index, nr_ids;
-       int j, len, ret, tc = 0;
        unsigned long *mask;
-
-       if (!netif_is_multiqueue(dev))
-               return -ENOENT;
-
-       index = get_netdev_queue_index(queue);
-
-       /* If queue belongs to subordinate dev use its map */
-       dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
+       unsigned int nr_ids;
+       int j, len, tc = 0;

        tc = netdev_txq_to_tc(dev, index);
        if (tc < 0)
                return -EINVAL;

        rcu_read_lock();
-       dev_maps = rcu_dereference(dev->xps_maps[XPS_CPUS]);
-       nr_ids = dev_maps ? dev_maps->nr_ids : nr_cpu_ids;
+       dev_maps = rcu_dereference(dev->xps_maps[type]);
+
+       /* Default to nr_cpu_ids/dev->num_rx_queues and do not just return 0
+        * when dev_maps hasn't been allocated yet, to be backward compatible.
+        */
+       nr_ids = dev_maps ? dev_maps->nr_ids :
+                (type == XPS_CPUS ? nr_cpu_ids : dev->num_rx_queues);

        mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
        if (!mask) {
-               ret = -ENOMEM;
-               goto err_rcu_unlock;
+               rcu_read_unlock();
+               return -ENOMEM;
        }

        if (!dev_maps || tc >= dev_maps->num_tc)
@@ -1368,11 +1364,24 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,

        len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
        bitmap_free(mask);
+
        return len < PAGE_SIZE ? len : -EINVAL;
+}

-err_rcu_unlock:
-       rcu_read_unlock();
-       return ret;
+static ssize_t xps_cpus_show(struct netdev_queue *queue, char *buf)
+{
+       struct net_device *dev = queue->dev;
+       unsigned int index;
+
+       if (!netif_is_multiqueue(dev))
+               return -ENOENT;
+
+       index = get_netdev_queue_index(queue);
+
+       /* If queue belongs to subordinate dev use its map */
+       dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
+
+       return xps_queue_show(dev, index, buf, XPS_CPUS);
 }

 static ssize_t xps_cpus_store(struct netdev_queue *queue,
So this patch has the same issue as the one that was removing the
rtnl_lock. Basically the sb_dev needs to still be protected by the
rtnl_lock. We might need to take the rtnl_lock and maybe make use of
the get_device/put_device logic to make certain the device cannot be
freed while you are passing it to xps_queue_show.

Re: [PATCH net-next v2 07/12] net: remove the xps possible_mask

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-09 08:53:54 

Quoting Alexander Duyck (2021-02-08 22:43:39)
On Mon, Feb 8, 2021 at 9:19 AM Antoine Tenart [off-list ref] wrote:
quoted
-static void clean_xps_maps(struct net_device *dev, const unsigned long *mask,
+static void clean_xps_maps(struct net_device *dev,
                           struct xps_dev_maps *dev_maps, u16 offset, u16 count,
                           bool is_rxqs_map)
 {
-       unsigned int nr_ids = dev_maps->nr_ids;
        bool active = false;
        int i, j;

-       for (j = -1; j = netif_attrmask_next(j, mask, nr_ids), j < nr_ids;)
-               active |= remove_xps_queue_cpu(dev, dev_maps, j, offset,
-                                              count);
+       for (j = 0; j < dev_maps->nr_ids; j++)
+               active |= remove_xps_queue_cpu(dev, dev_maps, j, offset, count);
        if (!active)
                reset_xps_maps(dev, dev_maps, is_rxqs_map);

-       if (!is_rxqs_map) {
-               for (i = offset + (count - 1); count--; i--) {
+       if (!is_rxqs_map)
+               for (i = offset + (count - 1); count--; i--)
                        netdev_queue_numa_node_write(
-                               netdev_get_tx_queue(dev, i),
-                               NUMA_NO_NODE);
-               }
-       }
+                               netdev_get_tx_queue(dev, i), NUMA_NO_NODE);
 }
This violates the coding-style guide for the kernel. The if statement
should still have braces as the for loop and
netdev_queue_numa_node_write are more than a single statement. I'd be
curious to see if checkpatch also complains about this because it
probably should.
You're right, I'll remove that change to comply with the coding style.

I reran checkpatch, even with --strict, and it did not complain. Maybe
because it's a rework, not strictly new code.

Thanks,
Antoine

Re: [PATCH net-next v2 09/12] net-sysfs: remove the rtnl lock when accessing the xps maps

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-09 09:17:29 

Quoting Alexander Duyck (2021-02-08 23:20:58)
On Mon, Feb 8, 2021 at 9:19 AM Antoine Tenart [off-list ref] wrote:
quoted
@@ -1328,17 +1328,12 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,

        index = get_netdev_queue_index(queue);

-       if (!rtnl_trylock())
-               return restart_syscall();
-
        /* If queue belongs to subordinate dev use its map */
        dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;

        tc = netdev_txq_to_tc(dev, index);
-       if (tc < 0) {
-               ret = -EINVAL;
-               goto err_rtnl_unlock;
-       }
+       if (tc < 0)
+               return -EINVAL;

        rcu_read_lock();
        dev_maps = rcu_dereference(dev->xps_maps[XPS_CPUS]);
So I think we hit a snag here. The sb_dev pointer is protected by the
rtnl_lock. So I don't think we can release the rtnl_lock until after
we are done with the dev pointer.

Also I am not sure it is safe to use netdev_txq_to_tc without holding
the lock. I don't know if we ever went through and guaranteed that it
will always work if the lock isn't held since in theory the device
could reprogram all the map values out from under us.

Odds are we should probably fix traffic_class_show as I suspect it
probably also needs to be holding the rtnl_lock to prevent any
possible races. I'll submit a patch for that.
Yet another possible race :-) Good catch, I thought about the one we
fixed already but not this one.

As the sb_dev pointer is protected by the rtnl lock, we'll have to keep
the lock. I'll move that patch at the end of the series (it'll be easier
to add the get_device/put_device logic with the xps_queue_show
function). I'll also move netdev_txq_to_tc out of xps_queue_show, to
call it under the rtnl lock taken.

Thanks,
Antoine

Re: [PATCH net-next v2 09/12] net-sysfs: remove the rtnl lock when accessing the xps maps

From: Antoine Tenart <atenart@kernel.org>
Date: 2021-02-09 09:27:15 

Quoting Antoine Tenart (2021-02-09 10:12:11)
As the sb_dev pointer is protected by the rtnl lock, we'll have to keep
the lock. I'll move that patch at the end of the series (it'll be easier
to add the get_device/put_device logic with the xps_queue_show
function). I'll also move netdev_txq_to_tc out of xps_queue_show, to
call it under the rtnl lock taken.
That was not very clear. I meant I won't remove the rtnl lock, but will
try not to take it for too long, using get_device/put_device. We'll see
if I'll have a dedicated patch for that or not.

[net] 81bb8ff453: assertion_failed

From: kernel test robot <hidden>
Date: 2021-02-23 06:13:45 

Greeting,

FYI, we noticed the following commit (built with gcc-9):

commit: 81bb8ff453eb20410103684e277befb5bc96f025 ("[PATCH net-next v2 06/12] net: assert the rtnl lock is held when calling __netif_set_xps_queue")
url: https://github.com/0day-ci/linux/commits/Antoine-Tenart/net-xps-improve-the-xps-maps-handling/20210209-081506
base: https://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git 6626a0266566c5aea16178c5e6cd7fc4db3f2f56

in testcase: boot

on test machine: qemu-system-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 8G

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


+-------------------------------------------------------------------------+------------+------------+
|                                                                         | 65df35412a | 81bb8ff453 |
+-------------------------------------------------------------------------+------------+------------+
| assertion_failed                                                        | 0          | 35         |
| WARNING:at_net/core/dev.c:#__netif_set_xps_queue                        | 0          | 35         |
| EIP:__netif_set_xps_queue                                               | 0          | 35         |
+-------------------------------------------------------------------------+------------+------------+


If you fix the issue, kindly add following tag
Reported-by: kernel test robot <redacted>


[  104.847236] ------------[ cut here ]------------
[  104.848653] RTNL: assertion failed at net/core/dev.c (2619)
[  104.850136] WARNING: CPU: 0 PID: 1 at net/core/dev.c:2619 __netif_set_xps_queue+0xb37/0xc00
[  104.851720] Modules linked in:
[  104.852896] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G S      W         5.11.0-rc4-00641-g81bb8ff453eb #1
[  104.854579] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
[  104.856184] EIP: __netif_set_xps_queue+0xb37/0xc00
[  104.857556] Code: 5d c3 80 3d 30 2e 27 d6 00 0f 85 14 f5 ff ff 68 3b 0a 00 00 68 ab 13 65 d5 68 44 e8 d9 d4 c6 05 30 2e 27 d6 01 e8 6e 70 89 00 <0f> 0b 83 c4 0c e9 ef f4 ff ff 8b 5d c4 85 db 0f 84 7a fe ff ff 8b
[  104.861089] EAX: 0000002f EBX: 00000000 ECX: 00000001 EDX: 00000000
[  104.862646] ESI: 00000000 EDI: 00000001 EBP: c1c67d94 ESP: c1c67d34
[  104.864181] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00010282
[  104.865807] CR0: 80050033 CR2: 00000000 CR3: 16932000 CR4: 000406d0
[  104.867346] Call Trace:
[  104.868607]  ? rcu_read_lock_sched_held+0x47/0x80
[  104.870085]  ? find_next_bit+0xf/0x20
[  104.871451]  ? cpumask_next+0x1f/0x40
[  104.872818]  ? cpumask_next_wrap+0x21/0x60
[  104.874195]  virtnet_set_affinity+0x135/0x1a0
[  104.875604]  init_vqs+0x212/0x260
[  104.876932]  virtnet_probe+0x38a/0x880
[  104.878266]  ? virtio_vdpa_get_status+0x1c/0x20
[  104.879649]  virtio_dev_probe+0x1a8/0x280
[  104.881046]  really_probe+0x18d/0x400
[  104.882368]  driver_probe_device+0xd9/0x1a0
[  104.883690]  ? mutex_lock_nested+0x19/0x20
[  104.885038]  ? __device_driver_lock+0x25/0x60
[  104.886387]  device_driver_attach+0x49/0x60
[  104.887710]  __driver_attach+0x81/0x140
[  104.889018]  ? bind_store+0x100/0x100
[  104.890286]  ? device_driver_attach+0x60/0x60
[  104.891584]  bus_for_each_dev+0x5d/0xa0
[  104.892868]  driver_attach+0x19/0x20
[  104.894063]  ? device_driver_attach+0x60/0x60
[  104.895304]  bus_add_driver+0x117/0x1e0
[  104.896497]  driver_register+0x66/0xc0
[  104.897707]  ? veth_init+0x14/0x14
[  104.898842]  register_virtio_driver+0x1b/0x40
[  104.900053]  virtio_net_driver_init+0x61/0x86
[  104.901299]  do_one_initcall+0x60/0x320
[  104.902500]  ? rcu_read_lock_sched_held+0x47/0x80
[  104.903732]  ? trace_initcall_level+0x84/0xac
[  104.904976]  kernel_init_freeable+0x208/0x257
[  104.906177]  ? rest_init+0x22d/0x22d
[  104.907304]  kernel_init+0xd/0xf3
[  104.908386]  ret_from_fork+0x1c/0x28
[  104.909580] irq event stamp: 51665545
[  104.910652] hardirqs last  enabled at (51665553): [<cdfc328d>] console_unlock+0x4cd/0x5e0
[  104.912085] hardirqs last disabled at (51665560): [<cdfc31f5>] console_unlock+0x435/0x5e0
[  104.913537] softirqs last  enabled at (51664338): [<d3016930>] __do_softirq+0x2f0/0x44b
[  104.914904] softirqs last disabled at (51664333): [<cdecb405>] call_on_stack+0x45/0x60
[  104.916226] ---[ end trace b6addf977bb74596 ]---



To reproduce:

        # build kernel
	cd linux
	cp config-5.11.0-rc4-00641-g81bb8ff453eb .config
	make HOSTCC=gcc-9 CC=gcc-9 ARCH=i386 olddefconfig prepare modules_prepare bzImage

        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email



Thanks,
Oliver Sang
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help