To avoid dereference of null pointer in case of the failure of alloc.
Therefore, it might be better to change the return type of
efx_init_rx_recycle_ring(), efx_init_rx_queue(), efx_start_channels(),
efx_start_datapath() and efx_start_all(), and return -ENOMEM when alloc
fails and return 0 the others.
Also, efx_net_open(), efx_pm_thaw(), efx_realloc_channels(),
efx_reset_up() and efx_change_mtu() should deal with the return value of
efx_start_all().
By the way, I have no idea where the code come from, which does not
mention in the commit message.
But I find the same bug in another two places in the ethernet and I will
then commit the patches to repair them.
The Fixes tag below is the one I guess.

Fixes: 5a6681e22c14 ("sfc: separate out SFC4000 ("Falcon") support into new sfc-falcon driver")
Signed-off-by: Jiasheng Jiang <redacted>
---
Changelog:

v1 -> v2

*Change 1. Casade return -ENOMEM when alloc fails and deal with the
error.
---
 drivers/net/ethernet/sfc/ef100_netdev.c |  4 +++-
 drivers/net/ethernet/sfc/efx.c          |  9 ++++++--
 drivers/net/ethernet/sfc/efx_channels.c | 14 ++++++++++---
 drivers/net/ethernet/sfc/efx_channels.h |  2 +-
 drivers/net/ethernet/sfc/efx_common.c   | 28 ++++++++++++++++++-------
 drivers/net/ethernet/sfc/efx_common.h   |  2 +-
 drivers/net/ethernet/sfc/rx_common.c    | 14 ++++++++++---
 drivers/net/ethernet/sfc/rx_common.h    |  2 +-
 8 files changed, 56 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/sfc/ef100_netdev.c b/drivers/net/ethernet/sfc/ef100_netdev.c
index 67fe44db6b61..aaba36e40446 100644
--- a/drivers/net/ethernet/sfc/ef100_netdev.c
+++ b/drivers/net/ethernet/sfc/ef100_netdev.c

@@ -162,7 +162,9 @@ static int ef100_net_open(struct net_device *net_dev)
 	if (rc)
 		goto fail;
 
-	efx_start_all(efx);
+	rc = efx_start_all(efx);
+	if (rc)
+		goto fail;
 
 	/* Link state detection is normally event-driven; we have
 	 * to poll now because we could have missed a change

diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index c746ca7235f1..874301cda686 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c

@@ -540,7 +540,10 @@ int efx_net_open(struct net_device *net_dev)
 	 * before the monitor starts running */
 	efx_link_status_changed(efx);
 
-	efx_start_all(efx);
+	rc = efx_start_all(efx);
+	if (rc)
+		return rc;
+
 	if (efx->state == STATE_DISABLED || efx->reset_pending)
 		netif_device_detach(efx->net_dev);
 	efx_selftest_async_start(efx);

@@ -1224,7 +1227,9 @@ static int efx_pm_thaw(struct device *dev)
 		efx_mcdi_port_reconfigure(efx);
 		mutex_unlock(&efx->mac_lock);
 
-		efx_start_all(efx);
+		rc = efx_start_all(efx);
+		if (rc)
+			goto fail;
 
 		efx_device_attach_if_not_resetting(efx);
 

diff --git a/drivers/net/ethernet/sfc/efx_channels.c b/drivers/net/ethernet/sfc/efx_channels.c
index bb48a139dd15..451f7c6a7680 100644
--- a/drivers/net/ethernet/sfc/efx_channels.c
+++ b/drivers/net/ethernet/sfc/efx_channels.c

@@ -837,7 +837,10 @@ int efx_realloc_channels(struct efx_nic *efx, u32 rxq_entries, u32 txq_entries)
 			  "unable to restart interrupts on channel reallocation\n");
 		efx_schedule_reset(efx, RESET_TYPE_DISABLE);
 	} else {
-		efx_start_all(efx);
+		rc = efx_start_all(efx);
+		if (rc)
+			goto rollback;
+
 		efx_device_attach_if_not_resetting(efx);
 	}
 	return rc;

@@ -1055,11 +1058,12 @@ void efx_disable_interrupts(struct efx_nic *efx)
 	efx->type->irq_disable_non_ev(efx);
 }
 
-void efx_start_channels(struct efx_nic *efx)
+int efx_start_channels(struct efx_nic *efx)
 {
 	struct efx_tx_queue *tx_queue;
 	struct efx_rx_queue *rx_queue;
 	struct efx_channel *channel;
+	int ret;
 
 	efx_for_each_channel(channel, efx) {
 		efx_for_each_channel_tx_queue(tx_queue, channel) {

@@ -1068,7 +1072,10 @@ void efx_start_channels(struct efx_nic *efx)
 		}
 
 		efx_for_each_channel_rx_queue(rx_queue, channel) {
-			efx_init_rx_queue(rx_queue);
+			ret = efx_init_rx_queue(rx_queue);
+			if (ret)
+				return ret;
+
 			atomic_inc(&efx->active_queues);
 			efx_stop_eventq(channel);
 			efx_fast_push_rx_descriptors(rx_queue, false);

@@ -1077,6 +1084,7 @@ void efx_start_channels(struct efx_nic *efx)
 
 		WARN_ON(channel->rx_pkt_n_frags);
 	}
+	return 0;
 }
 
 void efx_stop_channels(struct efx_nic *efx)

diff --git a/drivers/net/ethernet/sfc/efx_channels.h b/drivers/net/ethernet/sfc/efx_channels.h
index d77ec1f77fb1..da38b6be5a45 100644
--- a/drivers/net/ethernet/sfc/efx_channels.h
+++ b/drivers/net/ethernet/sfc/efx_channels.h

@@ -42,7 +42,7 @@ void efx_remove_channel(struct efx_channel *channel);
 void efx_remove_channels(struct efx_nic *efx);
 void efx_fini_channels(struct efx_nic *efx);
 struct efx_channel *efx_copy_channel(const struct efx_channel *old_channel);
-void efx_start_channels(struct efx_nic *efx);
+int efx_start_channels(struct efx_nic *efx);
 void efx_stop_channels(struct efx_nic *efx);
 
 void efx_init_napi_channel(struct efx_channel *channel);

diff --git a/drivers/net/ethernet/sfc/efx_common.c b/drivers/net/ethernet/sfc/efx_common.c
index de797e1ac5a9..0b5fec7769ea 100644
--- a/drivers/net/ethernet/sfc/efx_common.c
+++ b/drivers/net/ethernet/sfc/efx_common.c

@@ -309,7 +309,10 @@ int efx_change_mtu(struct net_device *net_dev, int new_mtu)
 	efx_mac_reconfigure(efx, true);
 	mutex_unlock(&efx->mac_lock);
 
-	efx_start_all(efx);
+	rc = efx_start_all(efx);
+	if (rc)
+		return rc;
+
 	efx_device_attach_if_not_resetting(efx);
 	return 0;
 }

@@ -361,11 +364,12 @@ void efx_start_monitor(struct efx_nic *efx)
  * to propagate configuration changes (mtu, checksum offload), or
  * to clear hardware error conditions
  */
-static void efx_start_datapath(struct efx_nic *efx)
+static int efx_start_datapath(struct efx_nic *efx)
 {
 	netdev_features_t old_features = efx->net_dev->features;
 	bool old_rx_scatter = efx->rx_scatter;
 	size_t rx_buf_len;
+	int ret;
 
 	/* Calculate the rx buffer allocation parameters required to
 	 * support the current MTU, including padding for header

@@ -431,12 +435,15 @@ static void efx_start_datapath(struct efx_nic *efx)
 	efx->txq_wake_thresh = efx->txq_stop_thresh / 2;
 
 	/* Initialise the channels */
-	efx_start_channels(efx);
+	ret = efx_start_channels(efx);
+	if (ret)
+		return ret;
 
 	efx_ptp_start_datapath(efx);
 
 	if (netif_device_present(efx->net_dev))
 		netif_tx_wake_all_queues(efx->net_dev);
+	return 0;
 }
 
 static void efx_stop_datapath(struct efx_nic *efx)

@@ -524,8 +531,9 @@ static void efx_stop_port(struct efx_nic *efx)
  * is safe to call multiple times, so long as the NIC is not disabled.
  * Requires the RTNL lock.
  */
-void efx_start_all(struct efx_nic *efx)
+int efx_start_all(struct efx_nic *efx)
 {
+	int ret;
 	EFX_ASSERT_RESET_SERIALISED(efx);
 	BUG_ON(efx->state == STATE_DISABLED);
 

@@ -534,10 +542,12 @@ void efx_start_all(struct efx_nic *efx)
 	 */
 	if (efx->port_enabled || !netif_running(efx->net_dev) ||
 	    efx->reset_pending)
-		return;
+		return 0;
 
 	efx_start_port(efx);
-	efx_start_datapath(efx);
+	ret = efx_start_datapath(efx);
+	if (ret)
+		return ret;
 
 	/* Start the hardware monitor if there is one */
 	efx_start_monitor(efx);

@@ -557,6 +567,8 @@ void efx_start_all(struct efx_nic *efx)
 		efx->type->update_stats(efx, NULL, NULL);
 		spin_unlock_bh(&efx->stats_lock);
 	}
+
+	return 0;
 }
 
 /* Quiesce the hardware and software data path, and regular activity

@@ -786,7 +798,9 @@ int efx_reset_up(struct efx_nic *efx, enum reset_type method, bool ok)
 
 	mutex_unlock(&efx->mac_lock);
 
-	efx_start_all(efx);
+	rc = efx_start_all(efx);
+	if (rc)
+		goto fail;
 
 	if (efx->type->udp_tnl_push_ports)
 		efx->type->udp_tnl_push_ports(efx);

diff --git a/drivers/net/ethernet/sfc/efx_common.h b/drivers/net/ethernet/sfc/efx_common.h
index 65513fd0cf6c..adf84a64760b 100644
--- a/drivers/net/ethernet/sfc/efx_common.h
+++ b/drivers/net/ethernet/sfc/efx_common.h

@@ -28,7 +28,7 @@ void efx_fini_struct(struct efx_nic *efx);
 void efx_link_clear_advertising(struct efx_nic *efx);
 void efx_link_set_wanted_fc(struct efx_nic *efx, u8);
 
-void efx_start_all(struct efx_nic *efx);
+int efx_start_all(struct efx_nic *efx);
 void efx_stop_all(struct efx_nic *efx);
 
 void efx_net_stats(struct net_device *net_dev, struct rtnl_link_stats64 *stats);

diff --git a/drivers/net/ethernet/sfc/rx_common.c b/drivers/net/ethernet/sfc/rx_common.c
index 68fc7d317693..b7d974e25a43 100644
--- a/drivers/net/ethernet/sfc/rx_common.c
+++ b/drivers/net/ethernet/sfc/rx_common.c

@@ -131,7 +131,7 @@ void efx_discard_rx_packet(struct efx_channel *channel,
 	efx_free_rx_buffers(rx_queue, rx_buf, n_frags);
 }
 
-static void efx_init_rx_recycle_ring(struct efx_rx_queue *rx_queue)
+static int efx_init_rx_recycle_ring(struct efx_rx_queue *rx_queue)
 {
 	unsigned int bufs_in_recycle_ring, page_ring_size;
 	struct efx_nic *efx = rx_queue->efx;

@@ -150,7 +150,11 @@ static void efx_init_rx_recycle_ring(struct efx_rx_queue *rx_queue)
 					    efx->rx_bufs_per_page);
 	rx_queue->page_ring = kcalloc(page_ring_size,
 				      sizeof(*rx_queue->page_ring), GFP_KERNEL);
+	if (!rx_queue->page_ring)
+		return -ENOMEM;
+
 	rx_queue->page_ptr_mask = page_ring_size - 1;
+	return 0;
 }
 
 static void efx_fini_rx_recycle_ring(struct efx_rx_queue *rx_queue)

@@ -222,7 +226,7 @@ int efx_probe_rx_queue(struct efx_rx_queue *rx_queue)
 	return rc;
 }
 
-void efx_init_rx_queue(struct efx_rx_queue *rx_queue)
+int efx_init_rx_queue(struct efx_rx_queue *rx_queue)
 {
 	unsigned int max_fill, trigger, max_trigger;
 	struct efx_nic *efx = rx_queue->efx;

@@ -236,7 +240,9 @@ void efx_init_rx_queue(struct efx_rx_queue *rx_queue)
 	rx_queue->notified_count = 0;
 	rx_queue->removed_count = 0;
 	rx_queue->min_fill = -1U;
-	efx_init_rx_recycle_ring(rx_queue);
+	rc = efx_init_rx_recycle_ring(rx_queue);
+	if (rc)
+		return rc;
 
 	rx_queue->page_remove = 0;
 	rx_queue->page_add = rx_queue->page_ptr_mask + 1;

@@ -275,6 +281,8 @@ void efx_init_rx_queue(struct efx_rx_queue *rx_queue)
 
 	/* Set up RX descriptor ring */
 	efx_nic_init_rx(rx_queue);
+
+	return 0;
 }
 
 void efx_fini_rx_queue(struct efx_rx_queue *rx_queue)

diff --git a/drivers/net/ethernet/sfc/rx_common.h b/drivers/net/ethernet/sfc/rx_common.h
index 207ccd8ba062..16133d3f46b2 100644
--- a/drivers/net/ethernet/sfc/rx_common.h
+++ b/drivers/net/ethernet/sfc/rx_common.h

@@ -47,7 +47,7 @@ void efx_discard_rx_packet(struct efx_channel *channel,
 			   unsigned int n_frags);
 
 int efx_probe_rx_queue(struct efx_rx_queue *rx_queue);
-void efx_init_rx_queue(struct efx_rx_queue *rx_queue);
+int efx_init_rx_queue(struct efx_rx_queue *rx_queue);
 void efx_fini_rx_queue(struct efx_rx_queue *rx_queue);
 void efx_remove_rx_queue(struct efx_rx_queue *rx_queue);
 void efx_destroy_rx_queue(struct efx_rx_queue *rx_queue);

-- 
2.25.1