Joseph Qi
2014-Sep-16 04:04 UTC
[Ocfs2-devel] [PATCH] ocfs2/dlm: do not get resource spinlock if lockres is new
There is a deadlock case which reported by Guozhonghua
(guozhonghua at h3c.com):
https://oss.oracle.com/pipermail/ocfs2-devel/2014-September/010079.html
This case is caused by &res->spinlock and &dlm->master_lock
misordering in different threads. It was introduced by commit
8d400b81cc83 (ocfs2/dlm: Clean up refmap helpers).
Since lockres is new, it doesn't not require the &res->spinlock. So
remove it.
Signed-off-by: Joseph Qi <joseph.qi at huawei.com>
Reviewed-by: joyce.xue <xuejiufei at huawei.com>
---
fs/ocfs2/dlm/dlmmaster.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 3ec906e..e3cfa02 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -655,12 +655,9 @@ void dlm_lockres_clear_refmap_bit(struct dlm_ctxt *dlm,
clear_bit(bit, res->refmap);
}
-
-void dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
+static void __dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
struct dlm_lock_resource *res)
{
- assert_spin_locked(&res->spinlock);
-
res->inflight_locks++;
mlog(0, "%s: res %.*s, inflight++: now %u, %ps()\n", dlm->name,
@@ -668,6 +665,13 @@ void dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
__builtin_return_address(0));
}
+void dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
+ struct dlm_lock_resource *res)
+{
+ assert_spin_locked(&res->spinlock);
+ __dlm_lockres_grab_inflight_ref(dlm, res);
+}
+
void dlm_lockres_drop_inflight_ref(struct dlm_ctxt *dlm,
struct dlm_lock_resource *res)
{
@@ -894,10 +898,8 @@ lookup:
/* finally add the lockres to its hash bucket */
__dlm_insert_lockres(dlm, res);
- /* Grab inflight ref to pin the resource */
- spin_lock(&res->spinlock);
- dlm_lockres_grab_inflight_ref(dlm, res);
- spin_unlock(&res->spinlock);
+ /* since this lockres is new it doesn't not require the spinlock */
+ __dlm_lockres_grab_inflight_ref(dlm, res);
/* get an extra ref on the mle in case this is a BLOCK
* if so, the creator of the BLOCK may try to put the last
--
1.8.4.3