Re: [PATCH V5 6/7] blk-throttle: Split the service queue

[Jens Axboe <axboe@xxxxxxxxx>]

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);

-- 
Jens Axboe