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[PATCH V2] libcfs: Fix a sleep-in-atomic bug in cfs_wi_exit

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The driver may sleep under a spin lock, and the function call path is:
cfs_wi_exit (acquire the lock by spin_lock)
  LASSERT
    lbug_with_loc
      libcfs_debug_dumplog
        schedule and kthread_run --> may sleep

To fix it, all "LASSERT" is placed out of the spin_lock and spin_unlock.

Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
---
 drivers/staging/lustre/lnet/libcfs/workitem.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/lustre/lnet/libcfs/workitem.c b/drivers/staging/lustre/lnet/libcfs/workitem.c
index dbc2a9b..928d06d 100644
--- a/drivers/staging/lustre/lnet/libcfs/workitem.c
+++ b/drivers/staging/lustre/lnet/libcfs/workitem.c
@@ -111,22 +111,23 @@ struct cfs_wi_sched {
 {
 	LASSERT(!in_interrupt()); /* because we use plain spinlock */
 	LASSERT(!sched->ws_stopping);
+	LASSERT(wi->wi_running);
+	if (wi->wi_scheduled) {
+		LASSERT(!list_empty(&wi->wi_list));
+		LASSERT(sched->ws_nscheduled > 0);
+	}
 
 	spin_lock(&sched->ws_lock);
 
-	LASSERT(wi->wi_running);
 	if (wi->wi_scheduled) { /* cancel pending schedules */
-		LASSERT(!list_empty(&wi->wi_list));
 		list_del_init(&wi->wi_list);
-
-		LASSERT(sched->ws_nscheduled > 0);
 		sched->ws_nscheduled--;
 	}
 
-	LASSERT(list_empty(&wi->wi_list));
-
 	wi->wi_scheduled = 1; /* LBUG future schedule attempts */
 	spin_unlock(&sched->ws_lock);
+
+	LASSERT(list_empty(&wi->wi_list));
 }
 EXPORT_SYMBOL(cfs_wi_exit);
 
-- 
1.7.9.5

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[PATCH V2] libcfs: Fix a sleep-in-atomic bug in cfs_wi_exit Jia-Ju Bai <baijiaju1990@163.com> - 2017-05-31 10:00 +0200
  Re: [PATCH V2] libcfs: Fix a sleep-in-atomic bug in cfs_wi_exit Oleg Drokin <oleg.drokin@intel.com> - 2017-05-31 15:50 +0200
  Re: [PATCH V2] libcfs: Fix a sleep-in-atomic bug in cfs_wi_exit Greg KH <gregkh@linuxfoundation.org> - 2017-06-03 16:10 +0200

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