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authorVenky Shankar <vshankar@redhat.com>2016-01-27 17:04:18 +0530
committerVenky Shankar <vshankar@redhat.com>2016-01-28 05:22:29 -0800
commit786a8b395b09126a1151865c57ec2753a26facbb (patch)
tree900655718512bb0593e0cd7f41c367e9cc80f3b6
parenteb5e71c26d780fd5e440893fcc78fa91c36fe0c1 (diff)
features / bitrot: Prevent spurious pthread_cond_wait() wakeup
pthread_cond_wait() is prone to spurious wakeups and it's utmost necessarry to check a boolean predicate for thread continuation. See man(3) pthread_cond_wait() for details. The following is done in bitrot scrubber: if (list_empty (&fsscrub->scrublist)) pthread_cond_wait (&fsscrub->cond, &fsscrub->mutex); followed by: list_first_entry (&fsscrub->scrublist, ...) A spurious wakeup from pthread_cond_wait() with the absence of list_empty() check causes list_first_entry() to return garbage. Change-Id: I08786b9686b5503fcad6127e4c2a2cfac4bb7849 BUG: 1302201 Signed-off-by: Venky Shankar <vshankar@redhat.com> Reviewed-on: http://review.gluster.org/13302 Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com> Tested-by: Pranith Kumar Karampuri <pkarampu@redhat.com> Smoke: Gluster Build System <jenkins@build.gluster.com> CentOS-regression: Gluster Build System <jenkins@build.gluster.com> NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
-rw-r--r--xlators/features/bit-rot/src/bitd/bit-rot-scrub.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/xlators/features/bit-rot/src/bitd/bit-rot-scrub.c b/xlators/features/bit-rot/src/bitd/bit-rot-scrub.c
index 0a7212cd828..d95008ca9a2 100644
--- a/xlators/features/bit-rot/src/bitd/bit-rot-scrub.c
+++ b/xlators/features/bit-rot/src/bitd/bit-rot-scrub.c
@@ -1039,7 +1039,7 @@ _br_scrubber_find_scrubbable_entry (struct br_scrubber *fsscrub,
br_child_t *firstchild = NULL;
while (1) {
- if (list_empty (&fsscrub->scrublist))
+ while (list_empty (&fsscrub->scrublist))
pthread_cond_wait (&fsscrub->cond, &fsscrub->mutex);
firstchild = NULL;