In function bio_put_percpu_cache(), cache->nr_irq is read indirectly
in line 776 using READ_ONCE(). This ensures safe access in a
multi-threaded environment.
776 if (READ_ONCE(cache->nr_irq) + cache->nr > ALLOC_CACHE_MAX)
777 goto out_free;
However, the increment operation is performed directly in line 792 without
using WRITE_ONCE(), which can lead to potential inconsistencies in a
multi-threaded context.
792 cache->nr_irq++;
To ensure consistent protection against data races, this update
should utilize WRITE_ONCE.
Signed-off-by: Zilin Guan <zilinguan811@xxxxxxxxx>
---
block/bio.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/bio.c b/block/bio.c
index ac4d77c88932..e2648ba71bac 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -789,7 +789,7 @@ static inline void bio_put_percpu_cache(struct bio *bio)
bio_uninit(bio);
bio->bi_next = cache->free_list_irq;
cache->free_list_irq = bio;
- cache->nr_irq++;
+ WRITE_ONCE(cache->nr_irq, cache->nr_irq + 1);
} else {
goto out_free;
}
--
2.34.1
