linux-kernel - [PATCH 3.16 073/132] of: fix clang -Wunsequenced for be32_to

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Message-ID: <lsq.1568989415.920663841@decadent.org.uk>
Date:   Fri, 20 Sep 2019 15:23:35 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Rob Herring" <robh@...nel.org>,
        "Nick Desaulniers" <ndesaulniers@...gle.com>,
        "David Laight" <David.Laight@...LAB.COM>,
        "Phong Tran" <tranmanphong@...il.com>
Subject: [PATCH 3.16 073/132] of: fix clang -Wunsequenced for be32_to_cpu()

3.16.74-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Phong Tran <tranmanphong@...il.com>

commit 440868661f36071886ed360d91de83bd67c73b4f upstream.

Now, make the loop explicit to avoid clang warning.

./include/linux/of.h:238:37: warning: multiple unsequenced modifications
to 'cell' [-Wunsequenced]
                r = (r << 32) | be32_to_cpu(*(cell++));
                                                  ^~
./include/linux/byteorder/generic.h:95:21: note: expanded from macro
'be32_to_cpu'
                    ^
./include/uapi/linux/byteorder/little_endian.h:40:59: note: expanded
from macro '__be32_to_cpu'
                                                          ^
./include/uapi/linux/swab.h:118:21: note: expanded from macro '__swab32'
        ___constant_swab32(x) :                 \
                           ^
./include/uapi/linux/swab.h:18:12: note: expanded from macro
'___constant_swab32'
        (((__u32)(x) & (__u32)0x000000ffUL) << 24) |            \
                  ^

Signed-off-by: Phong Tran <tranmanphong@...il.com>
Reported-by: Nick Desaulniers <ndesaulniers@...gle.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/460
Suggested-by: David Laight <David.Laight@...LAB.COM>
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
[robh: fix up whitespace]
Signed-off-by: Rob Herring <robh@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 include/linux/of.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -171,8 +171,8 @@ extern struct device_node *of_find_all_n
 static inline u64 of_read_number(const __be32 *cell, int size)
 {
 	u64 r = 0;
-	while (size--)
-		r = (r << 32) | be32_to_cpu(*(cell++));
+	for (; size--; cell++)
+		r = (r << 32) | be32_to_cpu(*cell);
 	return r;
 }