[lkml]   [2020]   [Jun]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH 03/18] 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: Paul E. McKenney <>
Signed-off-by: Will Deacon <>
include/asm-generic/rwonce.h | 2 ++
1 file changed, 2 insertions(+)

diff --git a/include/asm-generic/rwonce.h b/include/asm-generic/rwonce.h
index 92cc2f223cb3..f9dfa88fc04d 100644
--- a/include/asm-generic/rwonce.h
+++ b/include/asm-generic/rwonce.h
@@ -33,7 +33,9 @@
* 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))

#define __READ_ONCE_SCALAR(x) \
({ \
 \ /
  Last update: 2020-06-30 19:39    [W:0.345 / U:8.844 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site