On 11/21/18 2:15 AM, Benny Halevy wrote:
>> +int iomap_dio_iopoll(struct kiocb *kiocb, bool spin)
>> +{
>> + struct iomap_dio *dio = kiocb->private;
>> + struct request_queue *q = READ_ONCE(dio->last_queue);
>> +
>> + if (!q || dio->cookie == BLK_QC_T_NONE)
>> + return 0;
>> + return blk_poll(q, READ_ONCE(dio->cookie), spin);
>
> How about:
> blk_qc_t cookie = READ_ONCE(dio->cookie);
>
> if (!q || cookie == BLK_QC_T_NONE)
> return 0;
> return blk_poll(q, cookie, spin);
>
> Is there a chance the dio->cookie in the if () condition
> will be stale?
I've rewritten this one, more importantly it needs to guard against
submission by ensuring that 'dio' is valid.
--
Jens Axboe
