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| author | Bart Van Assche <bvanassche@acm.org> | 2014-12-08 08:46:34 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2014-12-08 08:46:34 -0700 |
| commit | b32232073e8061b41258bff2a10a06a91677480a (patch) | |
| tree | 5cf6507cccea99afd291e0274c205c6474895881 /block | |
| parent | 6637fadf25657e619a50fde5ff3ae09a98d20eb5 (diff) | |
| download | lwn-b32232073e8061b41258bff2a10a06a91677480a.tar.gz lwn-b32232073e8061b41258bff2a10a06a91677480a.zip | |
blk-mq: fix hang in bt_get()
Avoid that if there are fewer hardware queues than CPU threads that
bt_get() can hang. The symptoms of the hang were as follows:
* All tags allocated for a particular hardware queue.
* (nr_tags) pending commands for that hardware queue.
* No pending commands for the software queues associated with that
hardware queue.
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-mq-tag.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 230ef3056b72..eb55492e6875 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -254,6 +254,13 @@ static int bt_get(struct blk_mq_alloc_data *data, if (tag != -1) break; + /* + * We're out of tags on this hardware queue, kick any + * pending IO submits before going to sleep waiting for + * some to complete. + */ + blk_mq_run_hw_queue(hctx, false); + blk_mq_put_ctx(data->ctx); io_schedule(); |