4.19-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit 0bb4d124d34044179b42a769a0c76f389ae973b6 ]
This field can be read or written without socket lock being held.
Add annotations to avoid load-store tearing.
Signed-off-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/sock.h | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h index 373e34b46a3c9..c0df14e5a0754 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1759,21 +1759,33 @@ static inline void sk_tx_queue_set(struct sock *sk, int tx_queue) /* sk_tx_queue_mapping accept only upto a 16-bit value */ if (WARN_ON_ONCE((unsigned short)tx_queue >= USHRT_MAX)) return; - sk->sk_tx_queue_mapping = tx_queue; + /* Paired with READ_ONCE() in sk_tx_queue_get() and + * other WRITE_ONCE() because socket lock might be not held. + */ + WRITE_ONCE(sk->sk_tx_queue_mapping, tx_queue); }
#define NO_QUEUE_MAPPING USHRT_MAX
static inline void sk_tx_queue_clear(struct sock *sk) { - sk->sk_tx_queue_mapping = NO_QUEUE_MAPPING; + /* Paired with READ_ONCE() in sk_tx_queue_get() and + * other WRITE_ONCE() because socket lock might be not held. + */ + WRITE_ONCE(sk->sk_tx_queue_mapping, NO_QUEUE_MAPPING); }
static inline int sk_tx_queue_get(const struct sock *sk) { - if (sk && sk->sk_tx_queue_mapping != NO_QUEUE_MAPPING) - return sk->sk_tx_queue_mapping; + if (sk) { + /* Paired with WRITE_ONCE() in sk_tx_queue_clear() + * and sk_tx_queue_set(). + */ + int val = READ_ONCE(sk->sk_tx_queue_mapping);
+ if (val != NO_QUEUE_MAPPING) + return val; + } return -1; }