[PATCH 01/17] staging: lustre: osc: fix race issues thanks to oap_lock

From: James Simmons
Date: Sun Apr 10 2016 - 09:18:17 EST


From: Sebastien Buisson <sbuisson@xxxxxxx>

Fix 'data race condition' defects found by Coverity version 6.5.0:

Data race condition (MISSING_LOCK)

Accessing variable without holding lock. Elsewhere,
this variable is accessed with lock held.

This patch is dedicated to code fragments involving oap_lock.

Signed-off-by: Sebastien Buisson <sbuisson@xxxxxxx>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-2744
Reviewed-on: http://review.whamcloud.com/6572
Reviewed-by: Oleg Drokin <oleg.drokin@xxxxxxxxx>
Reviewed-by: Andreas Dilger <andreas.dilger@xxxxxxxxx>
Signed-off-by: James Simmons <jsimmons@xxxxxxxxxxxxx>
---
drivers/staging/lustre/lustre/osc/osc_cache.c | 8 ++++++++
drivers/staging/lustre/lustre/osc/osc_io.c | 2 ++
2 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/drivers/staging/lustre/lustre/osc/osc_cache.c b/drivers/staging/lustre/lustre/osc/osc_cache.c
index 956d57b..846be76 100644
--- a/drivers/staging/lustre/lustre/osc/osc_cache.c
+++ b/drivers/staging/lustre/lustre/osc/osc_cache.c
@@ -1147,7 +1147,9 @@ static int osc_extent_make_ready(const struct lu_env *env,
last->oap_count = osc_refresh_count(env, last, OBD_BRW_WRITE);
LASSERT(last->oap_count > 0);
LASSERT(last->oap_page_off + last->oap_count <= PAGE_CACHE_SIZE);
+ spin_lock(&last->oap_lock);
last->oap_async_flags |= ASYNC_COUNT_STABLE;
+ spin_unlock(&last->oap_lock);
}

/* for the rest of pages, we don't need to call osf_refresh_count()
@@ -1156,7 +1158,9 @@ static int osc_extent_make_ready(const struct lu_env *env,
list_for_each_entry(oap, &ext->oe_pages, oap_pending_item) {
if (!(oap->oap_async_flags & ASYNC_COUNT_STABLE)) {
oap->oap_count = PAGE_CACHE_SIZE - oap->oap_page_off;
+ spin_lock(&last->oap_lock);
oap->oap_async_flags |= ASYNC_COUNT_STABLE;
+ spin_unlock(&last->oap_lock);
}
}

@@ -2350,6 +2354,10 @@ int osc_queue_async_io(const struct lu_env *env, struct cl_io *io,
oap->oap_cmd = cmd;
oap->oap_page_off = ops->ops_from;
oap->oap_count = ops->ops_to - ops->ops_from;
+ /*
+ * No need to hold a lock here,
+ * since this page is not in any list yet.
+ */
oap->oap_async_flags = 0;
oap->oap_brw_flags = brw_flags;

diff --git a/drivers/staging/lustre/lustre/osc/osc_io.c b/drivers/staging/lustre/lustre/osc/osc_io.c
index cf7743d..0f50465 100644
--- a/drivers/staging/lustre/lustre/osc/osc_io.c
+++ b/drivers/staging/lustre/lustre/osc/osc_io.c
@@ -168,8 +168,10 @@ static int osc_io_submit(const struct lu_env *env,
}

cl_page_list_move(qout, qin, page);
+ spin_lock(&oap->oap_lock);
oap->oap_async_flags = ASYNC_URGENT|ASYNC_READY;
oap->oap_async_flags |= ASYNC_COUNT_STABLE;
+ spin_unlock(&oap->oap_lock);

osc_page_submit(env, opg, crt, brw_flags);
list_add_tail(&oap->oap_pending_item, &list);
--
1.7.1