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Commit 70e0c8a4 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Greg Kroah-Hartman
Browse files

rds: add missing barrier to release_refill 



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: default avatarMikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d040e85a

net/rds/ib_recv.c

+1 −0
Original line number Diff line number Diff line
@@ -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