From: Will Deacon <will@kernel.org>
Date: Wed, 16 Oct 2019 00:30:47 +0000 (-0700)
Subject: asm/rwonce: Allow __READ_ONCE to be overridden by the architecture
X-Git-Tag: microblaze-v5.10~58^2~3^2~13
X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=b78b331a3f5c0773171dadd6bbfa2a2242b45604;p=linux-2.6-microblaze.git

asm/rwonce: Allow __READ_ONCE to be overridden by the architecture

The meat and potatoes of READ_ONCE() is defined by the __READ_ONCE()
macro, which uses a volatile casts in an attempt to avoid tearing of
byte, halfword, word and double-word accesses. Allow this to be
overridden by the architecture code in the case that things like memory
barriers are also required.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
---

diff --git a/include/asm-generic/rwonce.h b/include/asm-generic/rwonce.h
index 87584379da43..04586b55a7c2 100644
--- a/include/asm-generic/rwonce.h
+++ b/include/asm-generic/rwonce.h
@@ -43,7 +43,9 @@
  * atomicity or dependency ordering guarantees. Note that this may result
  * in tears!
  */
+#ifndef __READ_ONCE
 #define __READ_ONCE(x)	(*(const volatile __unqual_scalar_typeof(x) *)&(x))
+#endif
 
 #define __READ_ONCE_SCALAR(x)						\
 ({									\