[PATCH net 0/2] eth: fbnic: Fix drop stats support

[PATCH net 0/2] eth: fbnic: Fix drop stats support

[Mohsin Bashir]

Fix hardware drop stats support on the TX path of fbnic by addressing two
issues: ensure that tx_dropped stats are correctly copied to the
rtnl_link_stats64 struct, and protect the copying of drop stats from
fdb->hw_stats to the local variable with the hw_stats_lock to
ensure consistency.

Mohsin Bashir (2):
  eth: fbnic: Fix tx_dropped reporting
  eth: fbnic: Lock the tx_dropped update

 drivers/net/ethernet/meta/fbnic/fbnic_netdev.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

-- 
2.47.3

[PATCH net 1/2] eth: fbnic: Fix tx_dropped reporting

[Mohsin Bashir]

Correctly copy the tx_dropped stats from the fbd->hw_stats to the
rtnl_link_stats64 struct.

Fixes: 5f8bd2ce8269 ("eth: fbnic: add support for TMI stats")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Mohsin Bashir <mohsin.bashr@gmail.com>
---
 drivers/net/ethernet/meta/fbnic/fbnic_netdev.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c b/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c
index 7bd7812d9c06..dc295e1b8516 100644
--- a/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c
@@ -420,16 +420,16 @@ static void fbnic_get_stats64(struct net_device *dev,
 	tx_packets = stats->packets;
 	tx_dropped = stats->dropped;
 
-	stats64->tx_bytes = tx_bytes;
-	stats64->tx_packets = tx_packets;
-	stats64->tx_dropped = tx_dropped;
-
 	/* Record drops from Tx HW Datapath */
 	tx_dropped += fbd->hw_stats.tmi.drop.frames.value +
 		      fbd->hw_stats.tti.cm_drop.frames.value +
 		      fbd->hw_stats.tti.frame_drop.frames.value +
 		      fbd->hw_stats.tti.tbi_drop.frames.value;
 
+	stats64->tx_bytes = tx_bytes;
+	stats64->tx_packets = tx_packets;
+	stats64->tx_dropped = tx_dropped;
+
 	for (i = 0; i < fbn->num_tx_queues; i++) {
 		struct fbnic_ring *txr = fbn->tx[i];
 
-- 
2.47.3

Re: [PATCH net 1/2] eth: fbnic: Fix tx_dropped reporting

[Simon Horman]

On Fri, Aug 01, 2025 at 07:46:35PM -0700, Mohsin Bashir wrote:
> Correctly copy the tx_dropped stats from the fbd->hw_stats to the
> rtnl_link_stats64 struct.
> 
> Fixes: 5f8bd2ce8269 ("eth: fbnic: add support for TMI stats")
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Mohsin Bashir <mohsin.bashr@gmail.com>

Thanks,

I note that the local variable tx_dropped was being  saved to stats64
before it's values were accumulated from hw_stats.

Reviewed-by: Simon Horman <horms@kernel.org>

[PATCH net 2/2] eth: fbnic: Lock the tx_dropped update

[Mohsin Bashir]

Wrap copying of drop stats on TX path from fbd->hw_stats by the
hw_stats_lock. Currently, it is being performed outside the lock and
another thread accessing fbd->hw_stats can lead to inconsistencies.

Fixes: 5f8bd2ce8269 ("eth: fbnic: add support for TMI stats")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Mohsin Bashir <mohsin.bashr@gmail.com>
---
 drivers/net/ethernet/meta/fbnic/fbnic_netdev.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c b/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c
index dc295e1b8516..d0e381ad7bee 100644
--- a/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_netdev.c
@@ -421,10 +421,12 @@ static void fbnic_get_stats64(struct net_device *dev,
 	tx_dropped = stats->dropped;
 
 	/* Record drops from Tx HW Datapath */
+	spin_lock(&fbd->hw_stats_lock);
 	tx_dropped += fbd->hw_stats.tmi.drop.frames.value +
 		      fbd->hw_stats.tti.cm_drop.frames.value +
 		      fbd->hw_stats.tti.frame_drop.frames.value +
 		      fbd->hw_stats.tti.tbi_drop.frames.value;
+	spin_unlock(&fbd->hw_stats_lock);
 
 	stats64->tx_bytes = tx_bytes;
 	stats64->tx_packets = tx_packets;
-- 
2.47.3

Re: [PATCH net 2/2] eth: fbnic: Lock the tx_dropped update

[Simon Horman]

On Fri, Aug 01, 2025 at 07:46:36PM -0700, Mohsin Bashir wrote:
> Wrap copying of drop stats on TX path from fbd->hw_stats by the
> hw_stats_lock. Currently, it is being performed outside the lock and
> another thread accessing fbd->hw_stats can lead to inconsistencies.
> 
> Fixes: 5f8bd2ce8269 ("eth: fbnic: add support for TMI stats")
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: Mohsin Bashir <mohsin.bashr@gmail.com>

Thanks,

I note that hw_stats_lock is documented as protecting hw_stats.
And that it is already used for that purpose elsewhere in
fbnic_get_stats64().

I do wonder if some refactoring could allow only locking
hw_stats_lock once in fbnic_get_stats64(). But that line of thought
doesn't effect the correctness of this patch.

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH net 0/2] eth: fbnic: Fix drop stats support

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Fri,  1 Aug 2025 19:46:34 -0700 you wrote:
> Fix hardware drop stats support on the TX path of fbnic by addressing two
> issues: ensure that tx_dropped stats are correctly copied to the
> rtnl_link_stats64 struct, and protect the copying of drop stats from
> fdb->hw_stats to the local variable with the hw_stats_lock to
> ensure consistency.
> 
> Mohsin Bashir (2):
>   eth: fbnic: Fix tx_dropped reporting
>   eth: fbnic: Lock the tx_dropped update
> 
> [...]

Here is the summary with links:
  - [net,1/2] eth: fbnic: Fix tx_dropped reporting
    https://git.kernel.org/netdev/net/c/2972395d8fad
  - [net,2/2] eth: fbnic: Lock the tx_dropped update
    https://git.kernel.org/netdev/net/c/53abd9c86fd0

You are awesome, thank you!
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