[PATCH] libcfs: Fix a sleep-in-atomic bug in cfs_percpt_lock and cfs_percpt_unlock

[Jia-Ju Bai]

The driver may sleep under a spin lock, and the function call path is:
cfs_percpt_lock/cfs_percpt_unlock (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 <baijiaju1...@163.com>
---
 drivers/staging/lustre/lnet/libcfs/libcfs_lock.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/lustre/lnet/libcfs/libcfs_lock.c 
b/drivers/staging/lustre/lnet/libcfs/libcfs_lock.c
index 1967b97c..a2ce092f 100644
--- a/drivers/staging/lustre/lnet/libcfs/libcfs_lock.c
+++ b/drivers/staging/lustre/lnet/libcfs/libcfs_lock.c
@@ -113,9 +113,10 @@ struct cfs_percpt_lock *
 
        /* exclusive lock request */
        for (i = 0; i < ncpt; i++) {
+               if (!i)
+                       LASSERT(!pcl->pcl_locked);
                spin_lock(pcl->pcl_locks[i]);
                if (!i) {
-                       LASSERT(!pcl->pcl_locked);
                        /* nobody should take private lock after this
                         * so I wouldn't starve for too long time
                         */
@@ -141,11 +142,11 @@ struct cfs_percpt_lock *
        }
 
        for (i = ncpt - 1; i >= 0; i--) {
-               if (!i) {
-                       LASSERT(pcl->pcl_locked);
+               if (!i)
                        pcl->pcl_locked = 0;
-               }
                spin_unlock(pcl->pcl_locks[i]);
+               if (!i)
+                       LASSERT(pcl->pcl_locked);
        }
 }
 EXPORT_SYMBOL(cfs_percpt_unlock);
-- 
1.7.9.5