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Merge branch 'for-linus' of git://git.kernel.dk/linux-block

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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()"
This commit is contained in:
Linus Torvalds 2014-12-15 17:25:20 -08:00
commit 9b8ec916df
1 changed files with 3 additions and 1 deletions
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4
block/blk-mq-tag.c
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@ -248,8 +248,8 @@ static int bt_get(struct blk_mq_alloc_data *data,
if (!(data->gfp & __GFP_WAIT)) if (!(data->gfp & __GFP_WAIT))
return -1; return -1;
bs = bt_wait_ptr(bt, hctx);
do { do {
bs = bt_wait_ptr(bt, hctx);
prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE); prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE);
tag = __bt_get(hctx, bt, last_tag); tag = __bt_get(hctx, bt, last_tag);
@ -285,6 +285,8 @@ static int bt_get(struct blk_mq_alloc_data *data,
hctx = data->hctx; hctx = data->hctx;
bt = &hctx->tags->bitmap_tags; bt = &hctx->tags->bitmap_tags;
} }
finish_wait(&bs->wait, &wait);
bs = bt_wait_ptr(bt, hctx);
} while (1); } while (1);
finish_wait(&bs->wait, &wait); finish_wait(&bs->wait, &wait);