Hi list,
When I read code of dlm_get_lock_resource(), there is something not clear to me.
719 lookup:
720 spin_lock(&dlm->spinlock);
721 tmpres = __dlm_lookup_lockres_full(dlm, lockid, namelen, hash);
722 if (tmpres) {
723 int dropping_ref = 0;
724
725 spin_lock(&tmpres->spinlock);
726 if (tmpres->owner == dlm->node_num) {
727 BUG_ON(tmpres->state & DLM_LOCK_RES_DROPPING_REF);
728 dlm_lockres_grab_inflight_ref(dlm, tmpres);
729 } else if (tmpres->state & DLM_LOCK_RES_DROPPING_REF)
730 dropping_ref = 1;
731 spin_unlock(&tmpres->spinlock);
732 spin_unlock(&dlm->spinlock);
733
734 /* wait until done messaging the master, drop our ref to
allow
735 * the lockres to be purged, start over. */
736 if (dropping_ref) {
737 spin_lock(&tmpres->spinlock);
738 __dlm_wait_on_lockres_flags(tmpres,
DLM_LOCK_RES_DROPPING_REF);
739 spin_unlock(&tmpres->spinlock);
740 dlm_lockres_put(tmpres);
741 tmpres = NULL;
742 goto lookup;
743 }
744
745 mlog(0, "found in hash!\n");
746 if (res)
747 dlm_lockres_put(res);
748 res = tmpres;
749 goto leave;
750 }
If at line 721 tmpres found from hash, and its state is not
DLM_LOCK_RES_DROPPING_REF (dropping_ref
is 0), between line 733 and 748, is it possible to set tmpres->state to
DLM_LOCK_RES_DROPPING_REF ?
I don't see any protection for this race, maybe there is something I missed.
Can anybody give me a
hint ?
Thanks.
--
Coly Li
SuSE PRC Labs
_______________________________________________
Ocfs2-devel mailing list
[email protected]
http://oss.oracle.com/mailman/listinfo/ocfs2-devel
