[PATCH net-next 0/3] Fixes for devlink rate objects API

From: Dmytro Linkin <redacted>

Patch #1 fixes not decreased refcount of parent node for destroyed leaf
object.

Patch #2 fixes incorect eswitch mode check.

Patch #3 protects list traversing with a lock.

Dmytro Linkin (3):
  devlink: Decrease refcnt of parent rate object on leaf destroy
  devlink: Remove eswitch mode check for mode set call
  devlink: Protect rate list with lock while switching modes

 net/core/devlink.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

-- 
1.8.3.1

From: Dmytro Linkin <redacted>

Port functions, like SFs, can be deleted by the user when its leaf rate
object has parent node. In such case node refcnt won't be decreased
which blocks the node from deletion later.
Do simple refcnt decrease, since driver in cleanup stage. This:
1) assumes that driver took proper internal parent unset action;
2) allows to avoid nested callbacks call and deadlock.

Fixes: d75559845078 ("devlink: Allow setting parent node of rate objects")
Signed-off-by: Dmytro Linkin <redacted>
Reviewed-by: Jiri Pirko <redacted>
---
 net/core/devlink.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index 566ddd1..ba27395 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c

@@ -9275,6 +9275,8 @@ void devlink_rate_leaf_destroy(struct devlink_port *devlink_port)
 
 	mutex_lock(&devlink->lock);
 	devlink_rate_notify(devlink_rate, DEVLINK_CMD_RATE_DEL);
+	if (devlink_rate->parent)
+		refcount_dec(&devlink_rate->parent->refcnt);
 	list_del(&devlink_rate->list);
 	devlink_port->devlink_rate = NULL;
 	mutex_unlock(&devlink->lock);

-- 
1.8.3.1

From: Dmytro Linkin <redacted>

When eswitch is disabled, querying its current mode results in error.
Due to this when trying to set the eswitch mode for mlx5 devices, it
fails to set the eswitch switchdev mode.
Hence remove such check.

Fixes: a8ecb93ef03d ("devlink: Introduce rate nodes")
Signed-off-by: Dmytro Linkin <redacted>
Reviewed-by: Parav Pandit <redacted>
Reviewed-by: Jiri Pirko <redacted>
---
 net/core/devlink.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index ba27395..153d432 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c

@@ -2709,17 +2709,6 @@ static int devlink_rate_nodes_check(struct devlink *devlink, u16 mode,
 				    struct netlink_ext_ack *extack)
 {
 	struct devlink_rate *devlink_rate;
-	u16 old_mode;
-	int err;
-
-	if (!devlink->ops->eswitch_mode_get)
-		return -EOPNOTSUPP;
-	err = devlink->ops->eswitch_mode_get(devlink, &old_mode);
-	if (err)
-		return err;
-
-	if (old_mode == mode)
-		return 0;
 
 	list_for_each_entry(devlink_rate, &devlink->rate_list, list)
 		if (devlink_rate_is_node(devlink_rate)) {

-- 
1.8.3.1

From: Dmytro Linkin <redacted>

Devlink eswitch set command doesn't hold devlink->lock, which makes
possible race condition between rate list traversing and others devlink
rate KAPI calls, like devlink_rate_nodes_destroy().
Hold devlink lock while traversing the list.

Fixes: a8ecb93ef03d ("devlink: Introduce rate nodes")
Signed-off-by: Dmytro Linkin <redacted>
Reviewed-by: Parav Pandit <redacted>
Reviewed-by: Jiri Pirko <redacted>
---
 net/core/devlink.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index 153d432..8fdd04f 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c

@@ -2710,11 +2710,15 @@ static int devlink_rate_nodes_check(struct devlink *devlink, u16 mode,
 {
 	struct devlink_rate *devlink_rate;
 
+	/* Take the lock to sync with devlink_rate_nodes_destroy() */
+	mutex_lock(&devlink->lock);
 	list_for_each_entry(devlink_rate, &devlink->rate_list, list)
 		if (devlink_rate_is_node(devlink_rate)) {
+			mutex_unlock(&devlink->lock);
 			NL_SET_ERR_MSG_MOD(extack, "Rate node(s) exists.");
 			return -EBUSY;
 		}
+	mutex_unlock(&devlink->lock);
 	return 0;
 }
 

-- 
1.8.3.1

Hello:

This series was applied to netdev/net-next.git (refs/heads/master):

On Wed, 23 Jun 2021 16:43:12 +0300 you wrote:

From: Dmytro Linkin <redacted>

Patch #1 fixes not decreased refcount of parent node for destroyed leaf
object.

Patch #2 fixes incorect eswitch mode check.

[...]

Here is the summary with links:
  - [net-next,1/3] devlink: Decrease refcnt of parent rate object on leaf destroy
    https://git.kernel.org/netdev/net-next/c/1321ed5e7648
  - [net-next,2/3] devlink: Remove eswitch mode check for mode set call
    https://git.kernel.org/netdev/net-next/c/ff99324ded01
  - [net-next,3/3] devlink: Protect rate list with lock while switching modes
    https://git.kernel.org/netdev/net-next/c/a3e5e5797faa

You are awesome, thank you!
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