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* [PATCH 1/2] Fix race in igc_xdp_xmit_zc
@ 2022-04-15 21:04 ` Jeff Evanson
  0 siblings, 0 replies; 6+ messages in thread
From: Jeff Evanson @ 2022-04-15 21:04 UTC (permalink / raw)
  To: Jesse Brandeburg, Tony Nguyen, David S. Miller, Jakub Kicinski,
	Alexei Starovoitov, Daniel Borkmann, Jesper Dangaard Brouer,
	John Fastabend, intel-wired-lan, netdev, linux-kernel, bpf
  Cc: jeff.evanson, jeff.evanson

in igc_xdp_xmit_zc, initialize next_to_use while holding the netif_tx_lock
to prevent racing with other users of the tx ring

Signed-off-by: Jeff Evanson <jeff.evanson@qsc.com>
---
 drivers/net/ethernet/intel/igc/igc_main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 1c00ee310c19..a36a18c84aeb 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -2598,7 +2598,7 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
 	struct netdev_queue *nq = txring_txq(ring);
 	union igc_adv_tx_desc *tx_desc = NULL;
 	int cpu = smp_processor_id();
-	u16 ntu = ring->next_to_use;
+	u16 ntu;
 	struct xdp_desc xdp_desc;
 	u16 budget;
 
@@ -2607,6 +2607,8 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
 
 	__netif_tx_lock(nq, cpu);
 
+	ntu = ring->next_to_use;
+
 	budget = igc_desc_unused(ring);
 
 	while (xsk_tx_peek_desc(pool, &xdp_desc) && budget--) {
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [Intel-wired-lan] [PATCH 1/2] Fix race in igc_xdp_xmit_zc
@ 2022-04-15 21:04 ` Jeff Evanson
  0 siblings, 0 replies; 6+ messages in thread
From: Jeff Evanson @ 2022-04-15 21:04 UTC (permalink / raw)
  To: intel-wired-lan

in igc_xdp_xmit_zc, initialize next_to_use while holding the netif_tx_lock
to prevent racing with other users of the tx ring

Signed-off-by: Jeff Evanson <jeff.evanson@qsc.com>
---
 drivers/net/ethernet/intel/igc/igc_main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 1c00ee310c19..a36a18c84aeb 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -2598,7 +2598,7 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
 	struct netdev_queue *nq = txring_txq(ring);
 	union igc_adv_tx_desc *tx_desc = NULL;
 	int cpu = smp_processor_id();
-	u16 ntu = ring->next_to_use;
+	u16 ntu;
 	struct xdp_desc xdp_desc;
 	u16 budget;
 
@@ -2607,6 +2607,8 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
 
 	__netif_tx_lock(nq, cpu);
 
+	ntu = ring->next_to_use;
+
 	budget = igc_desc_unused(ring);
 
 	while (xsk_tx_peek_desc(pool, &xdp_desc) && budget--) {
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] Fix race in igc_xdp_xmit_zc
  2022-04-15 21:04 ` [Intel-wired-lan] " Jeff Evanson
@ 2022-04-18 17:39   ` Vinicius Costa Gomes
  -1 siblings, 0 replies; 6+ messages in thread
From: Vinicius Costa Gomes @ 2022-04-18 17:39 UTC (permalink / raw)
  To: Jeff Evanson, Jesse Brandeburg, Tony Nguyen, David S. Miller,
	Jakub Kicinski, Alexei Starovoitov, Daniel Borkmann,
	Jesper Dangaard Brouer, John Fastabend, intel-wired-lan, netdev,
	linux-kernel, bpf
  Cc: jeff.evanson, jeff.evanson

Hi Jeff,

Jeff Evanson <jeff.evanson@gmail.com> writes:

> in igc_xdp_xmit_zc, initialize next_to_use while holding the netif_tx_lock
> to prevent racing with other users of the tx ring

Some style things to change:
 - Some more details on what is the effect of the race condition, and
 perhaps the conditions to reproduce it (what I could imagine is that
 you would need two applications (one using AF_XDP and another one using
 AF_PACKET, for example) sending packets to the same queue.
 - I think this patch is solving a real problem, so directing this patch
 to the net-queue (using 'PATCH net-queue' as subject prefix) would make
 sense.
 - Please add the 'Fixes:' tag so this commit can be applied to any
 stable tree that makes sense.

Apart from those style changes, the code looks good.

Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>

>
> Signed-off-by: Jeff Evanson <jeff.evanson@qsc.com>
> ---
>  drivers/net/ethernet/intel/igc/igc_main.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index 1c00ee310c19..a36a18c84aeb 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -2598,7 +2598,7 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
>  	struct netdev_queue *nq = txring_txq(ring);
>  	union igc_adv_tx_desc *tx_desc = NULL;
>  	int cpu = smp_processor_id();
> -	u16 ntu = ring->next_to_use;
> +	u16 ntu;
>  	struct xdp_desc xdp_desc;
>  	u16 budget;
>  
> @@ -2607,6 +2607,8 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
>  
>  	__netif_tx_lock(nq, cpu);
>  
> +	ntu = ring->next_to_use;
> +
>  	budget = igc_desc_unused(ring);
>  
>  	while (xsk_tx_peek_desc(pool, &xdp_desc) && budget--) {
> -- 
> 2.17.1
>

-- 
Vinicius

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [Intel-wired-lan] [PATCH 1/2] Fix race in igc_xdp_xmit_zc
@ 2022-04-18 17:39   ` Vinicius Costa Gomes
  0 siblings, 0 replies; 6+ messages in thread
From: Vinicius Costa Gomes @ 2022-04-18 17:39 UTC (permalink / raw)
  To: intel-wired-lan

Hi Jeff,

Jeff Evanson <jeff.evanson@gmail.com> writes:

> in igc_xdp_xmit_zc, initialize next_to_use while holding the netif_tx_lock
> to prevent racing with other users of the tx ring

Some style things to change:
 - Some more details on what is the effect of the race condition, and
 perhaps the conditions to reproduce it (what I could imagine is that
 you would need two applications (one using AF_XDP and another one using
 AF_PACKET, for example) sending packets to the same queue.
 - I think this patch is solving a real problem, so directing this patch
 to the net-queue (using 'PATCH net-queue' as subject prefix) would make
 sense.
 - Please add the 'Fixes:' tag so this commit can be applied to any
 stable tree that makes sense.

Apart from those style changes, the code looks good.

Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>

>
> Signed-off-by: Jeff Evanson <jeff.evanson@qsc.com>
> ---
>  drivers/net/ethernet/intel/igc/igc_main.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index 1c00ee310c19..a36a18c84aeb 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -2598,7 +2598,7 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
>  	struct netdev_queue *nq = txring_txq(ring);
>  	union igc_adv_tx_desc *tx_desc = NULL;
>  	int cpu = smp_processor_id();
> -	u16 ntu = ring->next_to_use;
> +	u16 ntu;
>  	struct xdp_desc xdp_desc;
>  	u16 budget;
>  
> @@ -2607,6 +2607,8 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
>  
>  	__netif_tx_lock(nq, cpu);
>  
> +	ntu = ring->next_to_use;
> +
>  	budget = igc_desc_unused(ring);
>  
>  	while (xsk_tx_peek_desc(pool, &xdp_desc) && budget--) {
> -- 
> 2.17.1
>

-- 
Vinicius

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [Intel-wired-lan] [PATCH 1/2] Fix race in igc_xdp_xmit_zc
  2022-04-15 21:04 ` [Intel-wired-lan] " Jeff Evanson
@ 2022-04-20 10:37   ` Alexander Lobakin
  -1 siblings, 0 replies; 6+ messages in thread
From: Alexander Lobakin @ 2022-04-20 10:37 UTC (permalink / raw)
  To: Jeff Evanson
  Cc: Alexander Lobakin, Jesse Brandeburg, Tony Nguyen,
	David S. Miller, Jakub Kicinski, Alexei Starovoitov,
	Daniel Borkmann, Jesper Dangaard Brouer, John Fastabend,
	intel-wired-lan, netdev, linux-kernel, bpf

From: Jeff Evanson <jeff.evanson@gmail.com>
Date: Fri, 15 Apr 2022 15:04:21 -0600

> in igc_xdp_xmit_zc, initialize next_to_use while holding the netif_tx_lock
> to prevent racing with other users of the tx ring
> 
> Signed-off-by: Jeff Evanson <jeff.evanson@qsc.com>
> ---
>  drivers/net/ethernet/intel/igc/igc_main.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index 1c00ee310c19..a36a18c84aeb 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -2598,7 +2598,7 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
>  	struct netdev_queue *nq = txring_txq(ring);
>  	union igc_adv_tx_desc *tx_desc = NULL;
>  	int cpu = smp_processor_id();
> -	u16 ntu = ring->next_to_use;
> +	u16 ntu;

Please don't break the RCT (reverse christmas tree) style here. You
should move it to the bottom of the declaration block, ideally
combine it with the declaration of @budget as they're both u16s.

>  	struct xdp_desc xdp_desc;
>  	u16 budget;
>  
> @@ -2607,6 +2607,8 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
>  
>  	__netif_tx_lock(nq, cpu);
>  
> +	ntu = ring->next_to_use;
> +

There's no need for this empty newline I believe.

>  	budget = igc_desc_unused(ring);
>  
>  	while (xsk_tx_peek_desc(pool, &xdp_desc) && budget--) {
> -- 
> 2.17.1

Thanks,
Al

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [Intel-wired-lan] [PATCH 1/2] Fix race in igc_xdp_xmit_zc
@ 2022-04-20 10:37   ` Alexander Lobakin
  0 siblings, 0 replies; 6+ messages in thread
From: Alexander Lobakin @ 2022-04-20 10:37 UTC (permalink / raw)
  To: intel-wired-lan

From: Jeff Evanson <jeff.evanson@gmail.com>
Date: Fri, 15 Apr 2022 15:04:21 -0600

> in igc_xdp_xmit_zc, initialize next_to_use while holding the netif_tx_lock
> to prevent racing with other users of the tx ring
> 
> Signed-off-by: Jeff Evanson <jeff.evanson@qsc.com>
> ---
>  drivers/net/ethernet/intel/igc/igc_main.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index 1c00ee310c19..a36a18c84aeb 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -2598,7 +2598,7 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
>  	struct netdev_queue *nq = txring_txq(ring);
>  	union igc_adv_tx_desc *tx_desc = NULL;
>  	int cpu = smp_processor_id();
> -	u16 ntu = ring->next_to_use;
> +	u16 ntu;

Please don't break the RCT (reverse christmas tree) style here. You
should move it to the bottom of the declaration block, ideally
combine it with the declaration of @budget as they're both u16s.

>  	struct xdp_desc xdp_desc;
>  	u16 budget;
>  
> @@ -2607,6 +2607,8 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
>  
>  	__netif_tx_lock(nq, cpu);
>  
> +	ntu = ring->next_to_use;
> +

There's no need for this empty newline I believe.

>  	budget = igc_desc_unused(ring);
>  
>  	while (xsk_tx_peek_desc(pool, &xdp_desc) && budget--) {
> -- 
> 2.17.1

Thanks,
Al

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-04-20 10:41 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-04-15 21:04 [PATCH 1/2] Fix race in igc_xdp_xmit_zc Jeff Evanson
2022-04-15 21:04 ` [Intel-wired-lan] " Jeff Evanson
2022-04-18 17:39 ` Vinicius Costa Gomes
2022-04-18 17:39   ` [Intel-wired-lan] " Vinicius Costa Gomes
2022-04-20 10:37 ` Alexander Lobakin
2022-04-20 10:37   ` Alexander Lobakin

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