diff options
author | Susant Palai <spalai@redhat.com> | 2015-04-26 23:49:56 +0530 |
---|---|---|
committer | Shyamsundar Ranganathan <srangana@redhat.com> | 2015-04-29 07:02:00 -0700 |
commit | 6bde16f7dc4a43d85e488f25ad679abfd24e72d1 (patch) | |
tree | 269659fd8c93ec5dabe91fb51b9808342b775700 /xlators | |
parent | b3a966c241b5d5b8117f06a4c744c18b6a59bb18 (diff) |
dht: tackle thread race in dht_getxattr_cbk
problem:
1. When two threads execute in parallel in dht_getxattr_cbk
it may so happen that, both may find local->xattr to be NULL. As
a result dht_aggregate_xattr may not get executed.
2. In dht_getxattr_cbk,
thread1 thread2
T1 this_call_cnt = 2 -1
T2 this_call_cnt = 1 - 1
T3 fills local_xattr
T4 DHT_STACK_UNWIND -> local_wipe
T5 tries to dereference local
which is already freed,
leading to crash.
Solution:
for problem1: Execute critical section inside frame lock
to resolve race.
for problem2: Calculate this_call_count just before out section.
Change-Id: I9827ac8fafebb0c733a4e4f3c710b752f1cd45fa
BUG: 1215592
Signed-off-by: Susant Palai <spalai@redhat.com>
Reviewed-on: http://review.gluster.org/10389
Reviewed-by: Anuradha Talur <atalur@redhat.com>
Reviewed-by: N Balachandran <nbalacha@redhat.com>
Reviewed-by: Kotresh HR <khiremat@redhat.com>
Tested-by: NetBSD Build System
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>
Diffstat (limited to 'xlators')
-rw-r--r-- | xlators/cluster/dht/src/dht-common.c | 41 |
1 files changed, 24 insertions, 17 deletions
diff --git a/xlators/cluster/dht/src/dht-common.c b/xlators/cluster/dht/src/dht-common.c index 31270c8b8bc..12a283bd991 100644 --- a/xlators/cluster/dht/src/dht-common.c +++ b/xlators/cluster/dht/src/dht-common.c @@ -2767,29 +2767,36 @@ dht_getxattr_cbk (call_frame_t *frame, void *cookie, xlator_t *this, conf = this->private; local = frame->local; - this_call_cnt = dht_frame_return (frame); + LOCK (&frame->lock); + { + if (!xattr || (op_ret == -1)) { + local->op_ret = op_ret; + goto unlock; + } - if (!xattr || (op_ret == -1)) { - local->op_ret = op_ret; - goto out; - } + if (dict_get (xattr, conf->xattr_name)) { + dict_del (xattr, conf->xattr_name); + } - if (dict_get (xattr, conf->xattr_name)) { - dict_del (xattr, conf->xattr_name); - } + if (frame->root->pid >= 0) { + GF_REMOVE_INTERNAL_XATTR + ("trusted.glusterfs.quota*", xattr); + GF_REMOVE_INTERNAL_XATTR("trusted.pgfid*", xattr); + } - if (frame->root->pid >= 0 ) { - GF_REMOVE_INTERNAL_XATTR("trusted.glusterfs.quota*", xattr); - GF_REMOVE_INTERNAL_XATTR("trusted.pgfid*", xattr); - } + local->op_ret = 0; - local->op_ret = 0; + if (!local->xattr) { + local->xattr = dict_copy_with_ref (xattr, NULL); + } else { + dht_aggregate_xattr (local->xattr, xattr); + } - if (!local->xattr) { - local->xattr = dict_copy_with_ref (xattr, NULL); - } else { - dht_aggregate_xattr (local->xattr, xattr); } +unlock: + UNLOCK (&frame->lock); + + this_call_cnt = dht_frame_return (frame); out: if (is_last_call (this_call_cnt)) { DHT_STACK_UNWIND (getxattr, frame, local->op_ret, op_errno, |