From 188112722cce083c8f1a7d0d84f55c2cd885920c Mon Sep 17 00:00:00 2001
From: Jens Axboe <jaxboe@fusionio.com>
Date: Tue, 12 Apr 2011 10:11:24 +0200
Subject: [PATCH] block: add comment on why we save and disable interrupts in
flush_plug_list()
It's done at the top to avoid doing it for every queue we unplug.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
---
block/blk-core.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/block/blk-core.c b/block/blk-core.c
index d20ce1e849c8..0c0ea10e61ea 100644
--- 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);
--
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