diff options
Diffstat (limited to 'block/blk-throttle.c')
| -rw-r--r-- | block/blk-throttle.c | 23 |
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], |