linux-kernel - [PATCH 3/6] udp: Add annotations for udp_rmem

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Message-Id: <20200429100529.19645-4-jbi.octave@gmail.com>
Date:   Wed, 29 Apr 2020 11:05:25 +0100
From:   Jules Irenge <jbi.octave@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Jakub Kicinski <kuba@...nel.org>,
        netdev@...r.kernel.org (open list:NETWORKING [IPv4/IPv6])
Subject: [PATCH 3/6] udp: Add annotations for udp_rmem_release()

Sparse reports a warning

 warning: context imbalance in udp_rmem_release() - unexpected unlock

To fix this,
__acquire(&sk_queue->lock) and __release(&sk_queue->lock) annotations
are added in case the condition is not met.

This add basically tell Sparse and not GCC to shutdown the warning

Add __acquire(&sk_queue->lock) annotation
Add the __release(&sk_queue->lock) annotation

Signed-off-by: Jules Irenge <jbi.octave@...il.com>
---
 net/ipv4/udp.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 5ca12a945ac3..175bd14bfac8 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1382,6 +1382,9 @@ static void udp_rmem_release(struct sock *sk, int size, int partial,
 	sk_queue = &sk->sk_receive_queue;
 	if (!rx_queue_lock_held)
 		spin_lock(&sk_queue->lock);
+	else
+		/* annotation for sparse */
+		__acquire(&sk_queue->lock);
 
 
 	sk->sk_forward_alloc += size;
@@ -1398,6 +1401,9 @@ static void udp_rmem_release(struct sock *sk, int size, int partial,
 
 	if (!rx_queue_lock_held)
 		spin_unlock(&sk_queue->lock);
+	else
+		/* annotation for sparse */
+		__release(&sk_queue->lock);
 }
 
 /* Note: called with reader_queue.lock held.
-- 
2.25.3