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authorJan Kara <jack@suse.cz>2017-04-11 11:29:01 +0200
committerJens Axboe <axboe@fb.com>2017-04-11 08:09:14 -0600
commit3f19cd23f3a9420fe7bd98ad41d05e45fa6d4d47 (patch)
tree1070c884072bcc98912373ca6953c2010451b1a5
parentf5c0b0910ac4c1bc93474d7593cc73622fdfc822 (diff)
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block: Fix list corruption of blk stats callback list
When CFQ calls wbt_disable_default(), it will call blk_stat_remove_callback() to stop gathering IO statistics for the purposes of writeback throttling. Later, when request_queue is unregistered, wbt_exit() will call blk_stat_remove_callback() again which will try to delete callback from the list again and possibly cause list corruption. Fix the problem by making wbt_disable_default() called wbt_exit() which is properly guarded against being called multiple times. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
-rw-r--r--block/blk-wbt.c12
1 files changed, 4 insertions, 8 deletions
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index ffa80e11cf14..b3b79149d3a0 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -653,19 +653,15 @@ void wbt_set_write_cache(struct rq_wb *rwb, bool write_cache_on)
rwb->wc = write_cache_on;
}
- /*
- * Disable wbt, if enabled by default. Only called from CFQ, if we have
- * cgroups enabled
+/*
+ * Disable wbt, if enabled by default. Only called from CFQ.
*/
void wbt_disable_default(struct request_queue *q)
{
struct rq_wb *rwb = q->rq_wb;
- if (rwb && rwb->enable_state == WBT_STATE_ON_DEFAULT) {
- blk_stat_remove_callback(q, rwb->cb);
- rwb->win_nsec = rwb->min_lat_nsec = 0;
- wbt_update_limits(rwb);
- }
+ if (rwb && rwb->enable_state == WBT_STATE_ON_DEFAULT)
+ wbt_exit(q);
}
EXPORT_SYMBOL_GPL(wbt_disable_default);