Commit 9b8ec916 authored Dec 15, 2014 by Linus Torvalds

linux-block

Pull core block fix from Jens Axboe:
 "Jan reported a problem this morning with a crash in blk-mq, and after
  looking over the recent changes, it's obvious that the blk-mq-tag
  waitqueue handling change is buggy.  We could end up _not_ doing
  finish_wait() before switching to a new waitqueue, thus corrupting the
  wait task list"

* 'for-linus' of git://git.kernel.dk/linux-block:
  Revert "blk-mq: Micro-optimize bt_get()"

parents 27cb8823 35d37c66

block/blk-mq-tag.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -248,8 +248,8 @@ static int bt_get(struct blk_mq_alloc_data *data,
		if (!(data->gfp & __GFP_WAIT))
		return -1;

		do {
		bs = bt_wait_ptr(bt, hctx);
		do {
		prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE);

		tag = __bt_get(hctx, bt, last_tag);
		@@ -285,6 +285,8 @@ static int bt_get(struct blk_mq_alloc_data *data,
		hctx = data->hctx;
		bt = &hctx->tags->bitmap_tags;
		}
		finish_wait(&bs->wait, &wait);
		bs = bt_wait_ptr(bt, hctx);
		} while (1);

		finish_wait(&bs->wait, &wait);

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