| Message ID | 20190116190312.26843-1-idryomov@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | libceph: avoid KEEPALIVE_PENDING races in ceph_con_keepalive() | expand |
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index d5718284db57..3661cdd927f1 100644 --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -3206,9 +3206,10 @@ 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);
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@syzkaller.appspotmail.com Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Tested-by: Myungho Jung <mhjungk@gmail.com> --- net/ceph/messenger.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)