block/blk-iocost: annotate ioc_pd_stat reads with data_race()

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ioc_pd_stat() reads ioc->enabled, ioc->vtime_base_rate, and
iocg->last_stat without holding ioc->lock, which trips KCSAN since
ioc_adjust_base_vrate() and iocg_flush_stat_upward() write those
fields under ioc->lock.

Commit 35198e3230 fixed the same issue in ioc_qos_prfill() and
ioc_cost_model_prfill() by adding spin_lock_irq(&ioc->lock).  However,
those functions read configuration parameters (qos/model) that need
synchronized reads.  In contrast, ioc_pd_stat() only reads stat
values (vrate, usage) where stale reads are harmless, so data_race()
is more appropriate — it silences the KCSAN warning without adding
lock contention during high-frequency stat reads.

Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://patch.msgid.link/20260804054120.161933-1-cui.tao@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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Tao Cui 2026-08-04 13:41:20 +08:00 • committed by Jens Axboe

parent 3bf9a21e7b

commit 4d73bf0ca4

1 changed files with 6 additions and 6 deletions

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block/blk-iocost.c

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