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lib/plist.c: enforce memory ordering in plist_check_list

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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 <richard120310@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
I Hsin Cheng 2024-05-26 22:01:39 +08:00 committed by Andrew Morton
parent 87beb66918
commit 7abcb84f95
1 changed files with 2 additions and 2 deletions
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4
lib/plist.c
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@ -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);
}
}