block: add comment on why we save and disable interrupts in flush_plu…

…g_list() It's done at the top to avoid doing it for every queue we unplug. Signed-off-by: Jens Axboe <[email protected]>
cbmeeks · Apr 12, 2011 · 1881127 · 1881127
1 parent 94b5eb2
commit 1881127
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/block/blk-core.c b/block/blk-core.c
@@ -2696,6 +2696,11 @@ static void flush_plug_list(struct blk_plug *plug)
 
 	q = NULL;
 	depth = 0;
+
+	/*
+	 * Save and disable interrupts here, to avoid doing it for every
+	 * queue lock we have to take.
+	 */
 	local_irq_save(flags);
 	while (!list_empty(&list)) {
 		rq = list_entry_rq(list.next);