linux-kernel - [PATCH 3.10 278/319] kernel: Change ASSIGN_ONCE(val, x) to WRITE

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Message-Id: <1486322541-8206-179-git-send-email-w@1wt.eu>
Date:   Sun,  5 Feb 2017 20:21:40 +0100
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Christian Borntraeger <borntraeger@...ibm.com>,
        Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 278/319] kernel: Change ASSIGN_ONCE(val, x) to WRITE_ONCE(x, val)

From: Christian Borntraeger <borntraeger@...ibm.com>

commit 43239cbe79fc369f5d2160bd7f69e28b5c50a58c upstream.

Feedback has shown that WRITE_ONCE(x, val) is easier to use than
ASSIGN_ONCE(val,x).
There are no in-tree users yet, so lets change it for 3.19.

Signed-off-by: Christian Borntraeger <borntraeger@...ibm.com>
Acked-by: Peter Zijlstra <peterz@...radead.org>
Acked-by: Davidlohr Bueso <dave@...olabs.net>
Acked-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
[wt: backported only for next patch]

Signed-off-by: Willy Tarreau <w@....eu>
---
 include/linux/compiler.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 9df1978..236a4e3 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -208,7 +208,7 @@ static __always_inline void __read_once_size(volatile void *p, void *res, int si
 	}
 }
 
-static __always_inline void __assign_once_size(volatile void *p, void *res, int size)
+static __always_inline void __write_once_size(volatile void *p, void *res, int size)
 {
 	switch (size) {
 	case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
@@ -228,15 +228,15 @@ static __always_inline void __assign_once_size(volatile void *p, void *res, int
 /*
  * Prevent the compiler from merging or refetching reads or writes. The
  * compiler is also forbidden from reordering successive instances of
- * READ_ONCE, ASSIGN_ONCE and ACCESS_ONCE (see below), but only when the
+ * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
  * compiler is aware of some particular ordering.  One way to make the
  * compiler aware of ordering is to put the two invocations of READ_ONCE,
- * ASSIGN_ONCE or ACCESS_ONCE() in different C statements.
+ * WRITE_ONCE or ACCESS_ONCE() in different C statements.
  *
  * In contrast to ACCESS_ONCE these two macros will also work on aggregate
  * data types like structs or unions. If the size of the accessed data
  * type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
- * READ_ONCE() and ASSIGN_ONCE()  will fall back to memcpy and print a
+ * READ_ONCE() and WRITE_ONCE()  will fall back to memcpy and print a
  * compile-time warning.
  *
  * Their two major use cases are: (1) Mediating communication between
@@ -250,8 +250,8 @@ static __always_inline void __assign_once_size(volatile void *p, void *res, int
 #define READ_ONCE(x) \
 	({ typeof(x) __val; __read_once_size(&x, &__val, sizeof(__val)); __val; })
 
-#define ASSIGN_ONCE(val, x) \
-	({ typeof(x) __val; __val = val; __assign_once_size(&x, &__val, sizeof(__val)); __val; })
+#define WRITE_ONCE(x, val) \
+	({ typeof(x) __val; __val = val; __write_once_size(&x, &__val, sizeof(__val)); __val; })
 
 #endif /* __KERNEL__ */
 
-- 
2.8.0.rc2.1.gbe9624a