From 7abcb84f953df037d40fad66f2109db318dd155b Mon Sep 17 00:00:00 2001 From: I Hsin Cheng Date: Sun, 26 May 2024 22:01:39 +0800 Subject: [PATCH] lib/plist.c: enforce memory ordering in plist_check_list There exists an iteration over a plist in plist_check_list(), and memory dependency exists between variables "prev", "next" and "prev->next". As plist is used in the scheduling subsystem, we should guarantee the memory ordering between multiple processors. Using macro "WRITE_ONCE()" can help us to ensure the memory ordering as it was stated in "Documentation/memory-barriers.txt". Link: https://lkml.kernel.org/r/20240526140139.17220-1-richard120310@gmail.com Signed-off-by: I Hsin Cheng Signed-off-by: Andrew Morton --- lib/plist.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/plist.c b/lib/plist.c index 0d86ed7a76ac..2e51829d3db9 100644 --- a/lib/plist.c +++ b/lib/plist.c @@ -47,8 +47,8 @@ static void plist_check_list(struct list_head *top) plist_check_prev_next(top, prev, next); while (next != top) { - prev = next; - next = prev->next; + WRITE_ONCE(prev, next); + WRITE_ONCE(next, prev->next); plist_check_prev_next(top, prev, next); } }