[PATCH] NVMe: limit max completion iterations in nvme_process_cq()

[Jens Axboe]

On 11/14/2014 10:56 AM, Keith Busch wrote:
> On Fri, 14 Nov 2014, Jens Axboe wrote:
>> This is an unbounded loop. If we have per-cpu queues this is
>> usually not a problem, but if CPUs share a queue, then we could
>> have some of them continually queueing IO and the loop could take
>> forever to exit.
>>
>> Limit max iterations to the queue depth of the given completion
>> queue, which seems like a nice number to use.
> 
> I think the loop implicitly already has the same max iteration: the
> queue lock is held when it's called, so new commands can't be posted on
> the submission queue while the completions are reaped, so we can't loop
> more than the depth.

That's a good point, since we need the same queue lock to submit a new
command. Disregard!

-- 
Jens Axboe