The patch titled
Subject: lib/plist.c: enforce memory ordering in plist_check_list
has been added to the -mm mm-nonmm-unstable branch. Its filename is
lib-plistc-enforce-memory-ordering-in-plist_check_list.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-plistc-enforce-memory-ordering-in-plist_check_list.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: I Hsin Cheng <richard120310@xxxxxxxxx>
Subject: lib/plist.c: enforce memory ordering in plist_check_list
Date: Sun, 26 May 2024 22:01:39 +0800
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@xxxxxxxxx
Signed-off-by: I Hsin Cheng <richard120310@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/plist.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/lib/plist.c~lib-plistc-enforce-memory-ordering-in-plist_check_list
+++ a/lib/plist.c
@@ -47,8 +47,8 @@ static void plist_check_list(struct list
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);
}
}
_
Patches currently in -mm which might be from richard120310@xxxxxxxxx are
lib-plistc-enforce-memory-ordering-in-plist_check_list.patch
