staging/lustre/ldlm: Fix flock deadlock detection race (3fa08ae7) · Commits · 戴 / test

Deadlock isn't detected if 2 threads are trying to grant 2 locks which deadlock on each other. They call ldlm_flock_deadlock() simultaneously and deadlock ins't detected. The soulition is to add lock to blocking list before calling ldlm_flock_deadlock() Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-1602 Lustre-change: http://review.whamcloud.com/3277 Signed-off-by:

Andriy Skulysh <Andriy_Skulysh@xyratex.com> Reviewed-by:

Vitaly Fertman <vitaly_fertman@xyratex.com> Reviewed-by:

Bruce Korb <bruce_korb@xyratex.com> Reviewed-by:

Keith Mannthey <keith.mannthey@intel.com> Reviewed-by:

Oleg Drokin <oleg.drokin@intel.com> Signed-off-by:

Peng Tao <tao.peng@emc.com> Signed-off-by:

Andreas Dilger <andreas.dilger@intel.com> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/ldlm/ldlm_flock.c

+10 −6

Original line number	Diff line number	Diff line
		@@ -198,6 +198,7 @@ ldlm_flock_deadlock(struct ldlm_lock req, struct ldlm_lock bl_lock)
		if (lock == NULL)
		break;

		LASSERT(req != lock);
		flock = &lock->l_policy_data.l_flock;
		LASSERT(flock->owner == bl_owner);
		bl_owner = flock->blocking_owner;
		@@ -329,18 +330,21 @@ reprocess:
		RETURN(LDLM_ITER_STOP);
		}

		if (ldlm_flock_deadlock(req, lock)) {
		ldlm_flock_destroy(req, mode, *flags);
		*err = -EDEADLK;
		RETURN(LDLM_ITER_STOP);
		}

		/* add lock to blocking list before deadlock
		* check to prevent race */
		rc = ldlm_flock_blocking_link(req, lock);
		if (rc) {
		ldlm_flock_destroy(req, mode, *flags);
		*err = rc;
		RETURN(LDLM_ITER_STOP);
		}
		if (ldlm_flock_deadlock(req, lock)) {
		ldlm_flock_blocking_unlink(req);
		ldlm_flock_destroy(req, mode, *flags);
		*err = -EDEADLK;
		RETURN(LDLM_ITER_STOP);
		}

		ldlm_resource_add_lock(res, &res->lr_waiting, req);
		*flags \|= LDLM_FL_BLOCK_GRANTED;
		RETURN(LDLM_ITER_STOP);

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