From: Qingfang Deng <qingfang.deng@linux.dev>
To: Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Qingfang Deng <qingfang.deng@linux.dev>,
Breno Leitao <leitao@debian.org>,
Norbert Szetei <norbert@doyensec.com>,
Taegu Ha <hataegu0826@gmail.com>,
linux-ppp@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH net] ppp: annotate lockless queue empty check
Date: Tue, 11 Aug 2026 14:02:29 +0800 [thread overview]
Message-ID: <20260811060236.322284-1-qingfang.deng@linux.dev> (raw)
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
next reply other threads:[~2026-08-11 6:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-11 6:02 Qingfang Deng [this message]
2026-08-11 9:41 ` [PATCH net] ppp: annotate lockless queue empty check Breno Leitao
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