From: Boris Protopopov <bprotopopov@users.noreply.github.com>
Date: Tue, 8 Aug 2017 15:31:52 +0000 (-0400)
Subject: Add assert under lock to detect cases of dispach of a preallocated
X-Git-Tag: zfs-0.8.0-rc1~152^2~29
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9243b0fb4784803720a0a5336cc3ded969a779e6;p=zfs

Add assert under lock to detect cases of dispach of a preallocated

taskq work item to more than one queue concurrently. Also, please
see discussion in zfsonlinux/zfs#3840.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Boris Protopopov <boris.protopopov@actifio.com>
Closes #609
---

diff --git a/module/spl/spl-taskq.c b/module/spl/spl-taskq.c
index 4298b3c86..7cad9f76b 100644
--- a/module/spl/spl-taskq.c
+++ b/module/spl/spl-taskq.c
@@ -683,6 +683,12 @@ taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
 
 	spin_lock(&t->tqent_lock);
 
+	/*
+	 * Make sure the entry is not on some other taskq; it is important to
+	 * ASSERT() under lock
+	 */
+	ASSERT(taskq_empty_ent(t));
+
 	/*
 	 * Mark it as a prealloc'd task.  This is important
 	 * to ensure that we don't free it later.