2022-11-22 13:47:33

by Christoph Böhmwalder

[permalink] [raw]
Subject: [PATCH 1/4] lru_cache: use atomic operations when accessing lc->flags, always

From: Lars Ellenberg <[email protected]>

Or, depending on the way locking is implemented at the call sites,
some updates could be lost (has not been observed).

Signed-off-by: Lars Ellenberg <[email protected]>
Signed-off-by: Christoph Böhmwalder <[email protected]>
---
lib/lru_cache.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/lru_cache.c b/lib/lru_cache.c
index dc35464216d3..fec899386238 100644
--- a/lib/lru_cache.c
+++ b/lib/lru_cache.c
@@ -364,7 +364,7 @@ static struct lc_element *__lc_get(struct lru_cache *lc, unsigned int enr, unsig
struct lc_element *e;

PARANOIA_ENTRY();
- if (lc->flags & LC_STARVING) {
+ if (test_bit(__LC_STARVING, &lc->flags)) {
++lc->starving;
RETURN(NULL);
}
@@ -417,7 +417,7 @@ static struct lc_element *__lc_get(struct lru_cache *lc, unsigned int enr, unsig
* the LRU element, we have to wait ...
*/
if (!lc_unused_element_available(lc)) {
- __set_bit(__LC_STARVING, &lc->flags);
+ set_bit(__LC_STARVING, &lc->flags);
RETURN(NULL);
}

--
2.38.1