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authorSusant Palai <spalai@redhat.com>2015-04-26 23:49:56 +0530
committerShyamsundar Ranganathan <srangana@redhat.com>2015-04-29 07:02:00 -0700
commit6bde16f7dc4a43d85e488f25ad679abfd24e72d1 (patch)
tree269659fd8c93ec5dabe91fb51b9808342b775700 /xlators/cluster/dht/src/dht-common.c
parentb3a966c241b5d5b8117f06a4c744c18b6a59bb18 (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/cluster/dht/src/dht-common.c')
-rw-r--r--xlators/cluster/dht/src/dht-common.c41
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,