1 files changed, 9 insertions, 14 deletions

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 2d134b7c40a3..381b09bb562b 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -725,26 +725,21 @@ static void throtl_process_limit_change(struct throtl_data *td)
         struct throtl_grp *tg;
         struct hlist_node *pos, *n;
 
-        /*
-         * Make sure atomic_inc() effects from
-         * throtl_update_blkio_group_read_bps(), group of functions are
-         * visible.
-         * Is this required or smp_mb__after_atomic_inc() was suffcient
-         * after the atomic_inc().
-         */
-        smp_rmb();
         if (!atomic_read(&td->limits_changed))
                 return;
 
         throtl_log(td, "limit changed =%d", atomic_read(&td->limits_changed));
 
-        hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) {
-                /*
-                 * Do I need an smp_rmb() here to make sure tg->limits_changed
-                 * update is visible. I am relying on smp_rmb() at the
-                 * beginning of function and not putting a new one here.
-                 */
+        /*
+         * Make sure updates from throtl_update_blkio_group_read_bps() group
+         * of functions to tg->limits_changed are visible. We do not
+         * want update td->limits_changed to be visible but update to
+         * tg->limits_changed not being visible yet on this cpu. Hence
+         * the read barrier.
+         */
+        smp_rmb();
 
+        hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) {
                 if (throtl_tg_on_rr(tg) && tg->limits_changed) {
                         throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu"
                                 " riops=%u wiops=%u", tg->bps[READ],