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authorLai Jiangshan <laijs@cn.fujitsu.com>2013-04-04 10:05:38 +0800
committerTejun Heo <tj@kernel.org>2013-04-04 07:54:01 -0700
commit5c529597e922c26910fe49b8d5f93aeaca9a2415 (patch)
tree76da2d5ce97f35db5bfb1fef8610a8422713672d /kernel
parent229641a6f1f09e27a1f12fba38980f33f4c92975 (diff)
downloadlinux-5c529597e922c26910fe49b8d5f93aeaca9a2415.tar.bz2
workqueue: avoid false negative WARN_ON() in destroy_workqueue()
destroy_workqueue() performs several sanity checks before proceeding with destruction of a workqueue. One of the checks verifies that refcnt of each pwq (pool_workqueue) is over 1 as at that point there should be no in-flight work items and the only holder of pwq refs is the workqueue itself. This worked fine as a workqueue used to hold only one reference to its pwqs; however, since 4c16bd327c ("workqueue: implement NUMA affinity for unbound workqueues"), a workqueue may hold multiple references to its default pwq triggering this sanity check spuriously. Fix it by not triggering the pwq->refcnt assertion on default pwqs. An example spurious WARN trigger follows. WARNING: at kernel/workqueue.c:4201 destroy_workqueue+0x6a/0x13e() Hardware name: 4286C12 Modules linked in: sdhci_pci sdhci mmc_core usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video Pid: 361, comm: umount Not tainted 3.9.0-rc5+ #29 Call Trace: [<c04314a7>] warn_slowpath_common+0x7c/0x93 [<c04314e0>] warn_slowpath_null+0x22/0x24 [<c044796a>] destroy_workqueue+0x6a/0x13e [<c056dc01>] ext4_put_super+0x43/0x2c4 [<c04fb7b8>] generic_shutdown_super+0x4b/0xb9 [<c04fb848>] kill_block_super+0x22/0x60 [<c04fb960>] deactivate_locked_super+0x2f/0x56 [<c04fc41b>] deactivate_super+0x2e/0x31 [<c050f1e6>] mntput_no_expire+0x103/0x108 [<c050fdce>] sys_umount+0x2a2/0x2c4 [<c050fe0e>] sys_oldumount+0x1e/0x20 [<c085ba4d>] sysenter_do_call+0x12/0x38 tj: Rewrote description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/workqueue.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index dd2a4c49a39a..c273376ff73e 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4201,7 +4201,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
}
}
- if (WARN_ON(pwq->refcnt > 1) ||
+ if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) ||
WARN_ON(pwq->nr_active) ||
WARN_ON(!list_empty(&pwq->delayed_works))) {
mutex_unlock(&wq->mutex);