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authorRaghavendra G <rgowdapp@redhat.com>2015-02-24 10:25:16 +0530
committerRaghavendra G <rgowdapp@redhat.com>2015-02-25 23:15:22 -0800
commit2a60854e8360309347236852989d520a04975e9c (patch)
tree5d9c2b7703e226e522d4e539435614867c4f121e
parent9112806b02b1c8668acff87af62553462aa7cf48 (diff)
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>
-rw-r--r--xlators/cluster/dht/src/dht-common.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/xlators/cluster/dht/src/dht-common.c b/xlators/cluster/dht/src/dht-common.c
index 1847b2fe003..47e617230f9 100644
--- a/xlators/cluster/dht/src/dht-common.c
+++ b/xlators/cluster/dht/src/dht-common.c
@@ -363,9 +363,18 @@ dht_discover_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
unlock:
UNLOCK (&frame->lock);
out:
+ /* Make sure, the thread executing dht_discover_complete is the one
+ * which calls STACK_DESTROY (frame). In the case of "attempt_unwind",
+ * this makes sure that the thread don't call dht_frame_return, till
+ * call to dht_discover_complete is done.
+ */
+ if (attempt_unwind) {
+ dht_discover_complete (this, frame);
+ }
+
this_call_cnt = dht_frame_return (frame);
- if (is_last_call (this_call_cnt) || attempt_unwind) {
+ if (is_last_call (this_call_cnt) && !attempt_unwind) {
dht_discover_complete (this, frame);
}