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Message-Id: <20190215020855.176727-41-sashal@kernel.org> Date: Thu, 14 Feb 2019 21:08:19 -0500 From: Sasha Levin <sashal@...nel.org> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org Cc: Ilya Dryomov <idryomov@...il.com>, Sasha Levin <sashal@...nel.org>, ceph-devel@...r.kernel.org, netdev@...r.kernel.org Subject: [PATCH AUTOSEL 4.20 41/77] libceph: avoid KEEPALIVE_PENDING races in ceph_con_keepalive() From: Ilya Dryomov <idryomov@...il.com> [ Upstream commit 4aac9228d16458cedcfd90c7fb37211cf3653ac3 ] con_fault() can transition the connection into STANDBY right after ceph_con_keepalive() clears STANDBY in clear_standby(): libceph user thread ceph-msgr worker ceph_con_keepalive() mutex_lock(&con->mutex) clear_standby(con) mutex_unlock(&con->mutex) mutex_lock(&con->mutex) con_fault() ... if KEEPALIVE_PENDING isn't set set state to STANDBY ... mutex_unlock(&con->mutex) set KEEPALIVE_PENDING set WRITE_PENDING This triggers warnings in clear_standby() when either ceph_con_send() or ceph_con_keepalive() get to clearing STANDBY next time. I don't see a reason to condition queue_con() call on the previous value of KEEPALIVE_PENDING, so move the setting of KEEPALIVE_PENDING into the critical section -- unlike WRITE_PENDING, KEEPALIVE_PENDING could have been a non-atomic flag. Reported-by: syzbot+acdeb633f6211ccdf886@...kaller.appspotmail.com Signed-off-by: Ilya Dryomov <idryomov@...il.com> Tested-by: Myungho Jung <mhjungk@...il.com> Signed-off-by: Sasha Levin <sashal@...nel.org> --- net/ceph/messenger.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index 2f126eff275d..664f886f464d 100644 --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -3219,9 +3219,10 @@ void ceph_con_keepalive(struct ceph_connection *con) dout("con_keepalive %p\n", con); mutex_lock(&con->mutex); clear_standby(con); + con_flag_set(con, CON_FLAG_KEEPALIVE_PENDING); mutex_unlock(&con->mutex); - if (con_flag_test_and_set(con, CON_FLAG_KEEPALIVE_PENDING) == 0 && - con_flag_test_and_set(con, CON_FLAG_WRITE_PENDING) == 0) + + if (con_flag_test_and_set(con, CON_FLAG_WRITE_PENDING) == 0) queue_con(con); } EXPORT_SYMBOL(ceph_con_keepalive); -- 2.19.1
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