block/blk-throttle: silence !BLK_DEV_IO_TRACE variable warnings

If blk-throttle is enabled but blktrace is not, then the compiler will
notice that the following two variables are unused:

../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);
      |                              ^~~~~~~~~

Silence that my annotating them with __maybe_unused.

Fixes: 28ad83b774a6 ("blk-throttle: Split the service queue")
Link: https://lore.kernel.org/all/20250515130830.9671-1-aishwarya.tcv@arm.com/
Reported-by: Aishwarya <aishwarya.tcv@arm.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index bf4faac83662ca52ed57b50c660e629ea01fce3d..bd15357f23bd6c7ff93855c6964cec6c688e421b 100644 (file)
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1149,8 +1149,8 @@ again:
        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);