* [PATCH net] ppp: annotate lockless queue empty check
@ 2026-08-11 6:02 Qingfang Deng
2026-08-11 9:41 ` Breno Leitao
0 siblings, 1 reply; 2+ messages in thread
From: Qingfang Deng @ 2026-08-11 6:02 UTC (permalink / raw)
To: Andrew Lunn, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, Qingfang Deng, Breno Leitao, Norbert Szetei,
Taegu Ha, linux-ppp, netdev, linux-kernel
ppp_poll() checks whether pf->rq contains a packet without holding the
queue lock. skb_peek() requires appropriate locking or a private queue,
neither of which applies because ppp_input() can enqueue concurrently.
Only queue emptiness is needed, so use skb_queue_empty_lockless()
instead.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Qingfang Deng <qingfang.deng@linux.dev>
---
drivers/net/ppp/ppp_generic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index e1013621eb1d..1a610a18893b 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -556,7 +556,7 @@ static __poll_t ppp_poll(struct file *file, poll_table *wait)
return 0;
poll_wait(file, &pf->rwait, wait);
mask = EPOLLOUT | EPOLLWRNORM;
- if (skb_peek(&pf->rq))
+ if (!skb_queue_empty_lockless(&pf->rq))
mask |= EPOLLIN | EPOLLRDNORM;
if (pf->dead)
mask |= EPOLLHUP;
--
2.43.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net] ppp: annotate lockless queue empty check
2026-08-11 6:02 [PATCH net] ppp: annotate lockless queue empty check Qingfang Deng
@ 2026-08-11 9:41 ` Breno Leitao
0 siblings, 0 replies; 2+ messages in thread
From: Breno Leitao @ 2026-08-11 9:41 UTC (permalink / raw)
To: Qingfang Deng
Cc: Andrew Lunn, David S. Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, Norbert Szetei, Taegu Ha, linux-ppp, netdev,
linux-kernel
On Tue, Aug 11, 2026 at 02:02:29PM +0800, Qingfang Deng wrote:
> ppp_poll() checks whether pf->rq contains a packet without holding the
> queue lock. skb_peek() requires appropriate locking or a private queue,
> neither of which applies because ppp_input() can enqueue concurrently.
>
> Only queue emptiness is needed, so use skb_queue_empty_lockless()
> instead.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Qingfang Deng <qingfang.deng@linux.dev>
Reviewed-by: Breno Leitao <leitao@debian.org.
^ permalink raw reply [flat|nested] 2+ messages in thread
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