cluster/dht: serialize execution of dht_discover_complete and

STACK_DESTROY (frame).

In the current code, dht_discover_complete can be invoked because of:
1. attempt_unwind is true
2. we are processing reply from the last subvolume

In scenario 1, following race is possible:

T1: calls dht_frame_return.
T2: calls dht_frame_return. This happens to be last call and hence it
    invokes dht_discover_complete, goes ahead and destroys frame
T1: since attempt_unwind is true, calls
    dht_discover_complete. However, since frame is already freed, call
    to dht_discover_complete can result in a crash.

The fix is to make sure that destruction of the frame is done only by
the thread executing dht_discover_complete.

Change-Id: I45765b90c4a9d0af0b33f8911b564d99e12d099e
BUG: 1195120
Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
Reviewed-on: http://review.gluster.org/9729
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>
Reviewed-by: N Balachandran <nbalacha@redhat.com>

0 files changed, 0 insertions, 0 deletions