On 3/18/22 19:03, Bang Li wrote:
This patch reverts commit 7082a29c22ac ("ARC: use ACCESS_ONCE in cmpxchg
loop").
It is not necessary to use READ_ONCE() because cmpxchg contains barrier. We
can get it from commit d57f727264f1 ("ARC: add compiler barrier to LLSC
based cmpxchg").
Signed-off-by: Bang Li <libang.linu...@gmail.com>
Indeed this is not needed. However have you checked the code with and/wo
this change to see if it builds the same.
-Vineet
---
arch/arc/kernel/smp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
index 78e6d069b1c1..56c23f3e1309 100644
--- a/arch/arc/kernel/smp.c
+++ b/arch/arc/kernel/smp.c
@@ -274,7 +274,7 @@ static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
* and read back old value
*/
do {
- new = old = READ_ONCE(*ipi_data_ptr);
+ new = old = *ipi_data_ptr;
new |= 1U << msg;
} while (cmpxchg(ipi_data_ptr, old, new) != old);
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