netdev - [PATCH net 01/11] net: annotate data-races around sk->sk_reserved

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Date: Fri, 28 Jul 2023 15:03:08 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: Jamal Hadi Salim <jhs@...atatu.com>, Cong Wang <xiyou.wangcong@...il.com>, 
	Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>, Wei Wang <weiwan@...gle.com>
Subject: [PATCH net 01/11] net: annotate data-races around sk->sk_reserved_mem

sk_getsockopt() runs locklessly. This means sk->sk_reserved_mem
can be read while other threads are changing its value.

Add missing annotations where they are needed.

Fixes: 2bb2f5fb21b0 ("net: add new socket option SO_RESERVE_MEM")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Wei Wang <weiwan@...gle.com>
---
 net/core/sock.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 9370fd50aa2c9d84b86651433c0df338a1518547..bd201d15e72aad4ea0b11941eaaa992de706634a 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1007,7 +1007,7 @@ static void sock_release_reserved_memory(struct sock *sk, int bytes)
 	bytes = round_down(bytes, PAGE_SIZE);
 
 	WARN_ON(bytes > sk->sk_reserved_mem);
-	sk->sk_reserved_mem -= bytes;
+	WRITE_ONCE(sk->sk_reserved_mem, sk->sk_reserved_mem - bytes);
 	sk_mem_reclaim(sk);
 }
 
@@ -1044,7 +1044,8 @@ static int sock_reserve_memory(struct sock *sk, int bytes)
 	}
 	sk->sk_forward_alloc += pages << PAGE_SHIFT;
 
-	sk->sk_reserved_mem += pages << PAGE_SHIFT;
+	WRITE_ONCE(sk->sk_reserved_mem,
+		   sk->sk_reserved_mem + (pages << PAGE_SHIFT));
 
 	return 0;
 }
@@ -1973,7 +1974,7 @@ int sk_getsockopt(struct sock *sk, int level, int optname,
 		break;
 
 	case SO_RESERVE_MEM:
-		v.val = sk->sk_reserved_mem;
+		v.val = READ_ONCE(sk->sk_reserved_mem);
 		break;
 
 	case SO_TXREHASH:
-- 
2.41.0.585.gd2178a4bd4-goog