On 5/15/25 7:47 AM, Zizhi Wo wrote:
>
>
> 在 2025/5/15 21:39, Jens Axboe 写道:
>> On 5/15/25 7:08 AM, Aishwarya wrote:
>>> Observed the following build warning when building the next-20250515 kernel with defconfig+CONFIG_BLK_DEV_THROTTLING applied:
>>>
>>> Warning output:
>>>
>>> ../block/blk-throttle.c: In function 'throtl_pending_timer_fn':
>>> ../block/blk-throttle.c:1153:30: warning: unused variable 'bio_cnt_w' [-Wunused-variable]
>>> 1153 | unsigned int bio_cnt_w = sq_queued(sq, WRITE);
>>> | ^~~~~~~~~
>>> ../block/blk-throttle.c:1152:30: warning: unused variable 'bio_cnt_r' [-Wunused-variable]
>>> 1152 | unsigned int bio_cnt_r = sq_queued(sq, READ);
>>> | ^~~~~~~~~
>>>
>>>
>>> There?s no warning with defconfig alone, and I?ve confirmed that the warning appears when CONFIG_BLK_DEV_THROTTLING is explicitly enabled.
>>
>> This should fix it. The issue is if blktrace isn't enabled.
>>
>> diff --git a/block/blk-throttle.c b/block/blk-throttle.c
>> index bf4faac83662..bd15357f23bd 100644
>> --- a/block/blk-throttle.c
>> +++ b/block/blk-throttle.c
>> @@ -1149,8 +1149,8 @@ static void throtl_pending_timer_fn(struct timer_list *t)
>> dispatched = false;
>> while (true) {
>> - unsigned int bio_cnt_r = sq_queued(sq, READ);
>> - unsigned int bio_cnt_w = sq_queued(sq, WRITE);
>> + unsigned int __maybe_unused bio_cnt_r = sq_queued(sq, READ);
>> + unsigned int __maybe_unused bio_cnt_w = sq_queued(sq, WRITE);
>> throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u",
>> bio_cnt_r + bio_cnt_w, bio_cnt_r, bio_cnt_w);
>>
>
> Oops.. I didn't take that into account. Those two variables are only
> used in throtl_log. I'll check if there are any other similar issues and
> send out a fix patch shortly. Thanks for pointing it out!
Easy to miss, as it needs throttle enabled and blktrace not enabled.
I did test compile the above, and I didn't spot any other ones.
--
Jens Axboe
