From: Mikulas Patocka mpatocka@redhat.com
stable inclusion from stable-v5.10.138 commit fb1857c2e41a4b4d215b5e799016169a1356fc10 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I60QFD
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit 9f414eb409daf4f778f011cf8266d36896bb930b upstream.
The functions clear_bit and set_bit do not imply a memory barrier, thus it may be possible that the waitqueue_active function (which does not take any locks) is moved before clear_bit and it could miss a wakeup event.
Fix this bug by adding a memory barrier after clear_bit.
Signed-off-by: Mikulas Patocka mpatocka@redhat.com Cc: stable@vger.kernel.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Reviewed-by: Wei Li liwei391@huawei.com --- net/rds/ib_recv.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c index 6fdedd9dbbc2..cfbf0e129cba 100644 --- a/net/rds/ib_recv.c +++ b/net/rds/ib_recv.c @@ -363,6 +363,7 @@ static int acquire_refill(struct rds_connection *conn) static void release_refill(struct rds_connection *conn) { clear_bit(RDS_RECV_REFILL, &conn->c_flags); + smp_mb__after_atomic();
/* We don't use wait_on_bit()/wake_up_bit() because our waking is in a * hot path and finding waiters is very rare. We don't want to walk