blk-mq timeout question

From: Stefan Haberland
Date: Fri Jul 07 2017 - 09:46:20 EST

While changing the DASD device driver to use the blk-mq interfaces I found the following unexpected behavior:

In case of a timeout our complete callback is never called. Here is the sequence of events as I understood:

- timeout occurs
- blk_mq_check_expired() calls and checks blk_mark_rq_complete()
- our .timeout callback is called which returns BLK_EH_NOT_HANDLED and schedules delayed work
- our worker calls blk_mq_complete_request()
- this also checks blk_mark_rq_complete() and therefore never calls our complete callback

Should blk_clear_rq_complete() also be called for the BLK_EH_NOT_HANDLED case?