On 03/15/2016 08:01 PM, Jens Axboe wrote:
> On 03/15/2016 01:21 AM, Hannes Reinecke wrote:
>> We need to check for a valid index before accessing the array
>> element to avoid accessing invalid memory regions.
>>
>> Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
>> ---
>> block/blk-mq.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/block/blk-mq.c b/block/blk-mq.c
>> index 56c0a72..4ea87d5 100644
>> --- a/block/blk-mq.c
>> +++ b/block/blk-mq.c
>> @@ -544,6 +544,8 @@ EXPORT_SYMBOL(blk_mq_abort_requeue_list);
>>
>> struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags,
>> unsigned int tag)
>> {
>> + if (unlikely(tag >= tags->nr_tags))
>> + return NULL;
>> return tags->rqs[tag];
>> }
>> EXPORT_SYMBOL(blk_mq_tag_to_rq);
>
> I like adding the check, but I think we should kill the unlikely and
> just make it:
>
> if (tag < tags->nr_tags)
> return tags->rqs[tag];
>
> return NULL;
>
> instead. I'll apply it as such.
>
yeah, I had a discussion about the viability of the 'unlikely' flag
given modern compilers. No consensus was reached, so I left it in.
Removing it is fine by me, too.
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
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