Files
linux/net/ceph
Ilya Dryomov f3f0a9d17f libceph: avoid KEEPALIVE_PENDING races in ceph_con_keepalive()
commit 4aac9228d1 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-02-15 08:07:39 +01:00
..
2018-12-08 13:05:10 +01:00
2014-12-17 20:09:50 +03:00
2016-07-28 02:55:35 +02:00
2018-12-08 13:05:10 +01:00