[PATCH v2 7/7] [RFC] nvme: Fix a race condition

[Bart Van Assche]

On 10/11/16 09:46, Christoph Hellwig wrote:
> On Wed, Sep 28, 2016 at 05:01:45PM -0700, Bart Van Assche wrote:
>> Avoid that nvme_queue_rq() is still running when nvme_stop_queues()
>> returns. Untested.
>>
>> Signed-off-by: Bart Van Assche <bart.vanassche at sandisk.com>
>> Cc: Keith Busch <keith.busch at intel.com>
>> Cc: Christoph Hellwig <hch at lst.de>
>> Cc: Sagi Grimberg <sagi at grimberg.me>
>> ---
>>  drivers/nvme/host/core.c | 20 ++++++++++++--------
>>  1 file changed, 12 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>> index d791fba..98f1f29 100644
>> --- a/drivers/nvme/host/core.c
>> +++ b/drivers/nvme/host/core.c
>> @@ -201,13 +201,9 @@ fail:
>>
>>  void nvme_requeue_req(struct request *req)
>>  {
>> -	unsigned long flags;
>> -
>>  	blk_mq_requeue_request(req);
>> -	spin_lock_irqsave(req->q->queue_lock, flags);
>> -	if (!blk_mq_queue_stopped(req->q))
>> -		blk_mq_kick_requeue_list(req->q);
>> -	spin_unlock_irqrestore(req->q->queue_lock, flags);
>> +	WARN_ON_ONCE(blk_mq_queue_stopped(req->q));
>> +	blk_mq_kick_requeue_list(req->q);
>>  }
>>  EXPORT_SYMBOL_GPL(nvme_requeue_req);
>
> Can we just add a 'bool kick' argument to blk_mq_requeue_request and
> move all this handling to the core?

Hello Christoph,

That sounds like a good idea to me. Thanks also for the other review 
comments you posted on this patch series. I will rework patch 6/7 such 
that the code for waiting is moved into the SCSI core.

Bart.