On 05/03/2012 01:02 PM, Sasha Levin wrote:
On Thu, May 3, 2012 at 4:19 AM, Asias He<asias@xxxxxxxxxx> wrote:@@ -190,6 +194,7 @@ static void do_virtblk_request(struct request_queue *q) while ((req = blk_peek_request(q)) != NULL) { BUG_ON(req->nr_phys_segments + 2> vblk->sg_elems); + vblk->req_in_flight++; /* If this request fails, stop queue and wait for something to finish to restart it. */This is being increased before we know if the request will actually be sent, so if do_req() fails afterwards, req_in_flight would be increased but the request will never be sent. Which means we won't be able to unplug the device ever.
Yes, you are right. This introduces another race. I could do vblk->req_in_flight++ right after blk_start_request(req) to avoid this race.
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