[PATCH] block/blk-iocost: read ioc_pd_stat params inside ioc->lock

[PATCH] block/blk-iocost: read ioc_pd_stat params inside ioc->lock

[Tao Cui]

From: Tao Cui <cuitao@kylinos.cn>

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 35198e323001 ("blk-iocost: read params inside lock in sysfs
apis") fixed the same issue in ioc_qos_prfill() and
ioc_cost_model_prfill(), but ioc_pd_stat() was missed.

Add spin_lock_irq(&ioc->lock) around the reads, matching the fix
style of 35198e323001.

Fixes: 35198e323001 ("blk-iocost: read params inside lock in sysfs apis")
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
---
 block/blk-iocost.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 8b2aeba2e1e3..b491a6ab98ea 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3093,8 +3093,10 @@ static void ioc_pd_stat(struct blkg_policy_data *pd, struct seq_file *s)
 	struct ioc_gq *iocg = pd_to_iocg(pd);
 	struct ioc *ioc = iocg->ioc;
 
+	spin_lock_irq(&ioc->lock);
+
 	if (!ioc->enabled)
-		return;
+		goto out;
 
 	if (iocg->level == 0) {
 		unsigned vp10k = DIV64_U64_ROUND_CLOSEST(
@@ -3110,6 +3112,8 @@ static void ioc_pd_stat(struct blkg_policy_data *pd, struct seq_file *s)
 			iocg->last_stat.wait_us,
 			iocg->last_stat.indebt_us,
 			iocg->last_stat.indelay_us);
+out:
+	spin_unlock_irq(&ioc->lock);
 }
 
 static u64 ioc_weight_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
-- 
2.43.0