LU-3916 lprocfs: export lprocfs setup race

Protect setting export's exp_nid_stats.

Signed-off-by: Bobi Jam <bobijam.xu@intel.com>
Change-Id: I83e65f5ff851b8d8553cbedef6469e188d3502ff
Reviewed-on: http://review.whamcloud.com/7606
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Emoly Liu <emoly.liu@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>

diff --git a/lustre/obdclass/lprocfs_status.c b/lustre/obdclass/lprocfs_status.c
index 9d91157..885287c 100644 (file)
--- a/lustre/obdclass/lprocfs_status.c
+++ b/lustre/obdclass/lprocfs_status.c
@@ -1969,6 +1969,13 @@ int lprocfs_exp_setup(struct obd_export *exp, lnet_nid_t *nid, int *newnid)
         if (!nid || *nid == LNET_NID_ANY)
                 RETURN(0);
 
+       spin_lock(&exp->exp_lock);
+       if (exp->exp_nid_stats != NULL) {
+               spin_unlock(&exp->exp_lock);
+               RETURN(-EALREADY);
+       }
+       spin_unlock(&exp->exp_lock);
+
         obd = exp->exp_obd;
 
         CDEBUG(D_CONFIG, "using hash %p\n", obd->obd_nid_stats_hash);
@@ -1988,19 +1995,12 @@ int lprocfs_exp_setup(struct obd_export *exp, lnet_nid_t *nid, int *newnid)
                old_stat, libcfs_nid2str(*nid),
                cfs_atomic_read(&new_stat->nid_exp_ref_count));
 
-        /* We need to release old stats because lprocfs_exp_cleanup() hasn't
-         * been and will never be called. */
-        if (exp->exp_nid_stats) {
-                nidstat_putref(exp->exp_nid_stats);
-                exp->exp_nid_stats = NULL;
-        }
-
-        /* Return -EALREADY here so that we know that the /proc
-         * entry already has been created */
-        if (old_stat != new_stat) {
-                exp->exp_nid_stats = old_stat;
-                GOTO(destroy_new, rc = -EALREADY);
-        }
+       /* Return -EALREADY here so that we know that the /proc
+        * entry already has been created */
+       if (old_stat != new_stat) {
+               nidstat_putref(old_stat);
+               GOTO(destroy_new, rc = -EALREADY);
+       }
         /* not found - create */
         OBD_ALLOC(buffer, LNET_NIDSTR_SIZE);
         if (buffer == NULL)
@@ -2036,7 +2036,9 @@ int lprocfs_exp_setup(struct obd_export *exp, lnet_nid_t *nid, int *newnid)
                 GOTO(destroy_new_ns, rc);
         }
 
-        exp->exp_nid_stats = new_stat;
+       spin_lock(&exp->exp_lock);
+       exp->exp_nid_stats = new_stat;
+       spin_unlock(&exp->exp_lock);
         *newnid = 1;
         /* protect competitive add to list, not need locking on destroy */
        spin_lock(&obd->obd_nid_lock);