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authorRichard Kennedy <richard@rsk.demon.co.uk>2010-04-14 20:54:03 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2010-05-12 14:57:05 -0700
commita59bb6a18c9fc9ed48804d5d2868ce2d301925e5 (patch)
tree98c4fdd272974667d56253fb17433e2fd6cd33bc /block
parent48a5414b50f47157ef4ff0ab52a86144f1804c19 (diff)
downloadlwn-a59bb6a18c9fc9ed48804d5d2868ce2d301925e5.tar.gz
lwn-a59bb6a18c9fc9ed48804d5d2868ce2d301925e5.zip
block: ensure jiffies wrap is handled correctly in blk_rq_timed_out_timer
commit a534dbe96e9929c7245924d8252d89048c23d569 upstream. blk_rq_timed_out_timer() relied on blk_add_timer() never returning a timer value of zero, but commit 7838c15b8dd18e78a523513749e5b54bda07b0cb removed the code that bumped this value when it was zero. Therefore when jiffies is near wrap we could get unlucky & not set the timeout value correctly. This patch uses a flag to indicate that the timeout value was set and so handles jiffies wrap correctly, and it keeps all the logic in one function so should be easier to maintain in the future. Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk> Signed-off-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'block')
-rw-r--r--block/blk-timeout.c12
1 files changed, 5 insertions, 7 deletions
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index 1ba7e0aca878..4f0c06c7a338 100644
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -109,6 +109,7 @@ void blk_rq_timed_out_timer(unsigned long data)
struct request_queue *q = (struct request_queue *) data;
unsigned long flags, next = 0;
struct request *rq, *tmp;
+ int next_set = 0;
spin_lock_irqsave(q->queue_lock, flags);
@@ -122,16 +123,13 @@ void blk_rq_timed_out_timer(unsigned long data)
if (blk_mark_rq_complete(rq))
continue;
blk_rq_timed_out(rq);
- } else if (!next || time_after(next, rq->deadline))
+ } else if (!next_set || time_after(next, rq->deadline)) {
next = rq->deadline;
+ next_set = 1;
+ }
}
- /*
- * next can never be 0 here with the list non-empty, since we always
- * bump ->deadline to 1 so we can detect if the timer was ever added
- * or not. See comment in blk_add_timer()
- */
- if (next)
+ if (next_set)
mod_timer(&q->timeout, round_jiffies_up(next));
spin_unlock_irqrestore(q->queue_lock, flags);