[PATCH] Misuse of sizeof

[PATCH] Misuse of sizeof

[Giangiacomo Mariotti]

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IMO there's a bug in the use of sizeof in /arch/x86/boot/main.c, it's
also a strange style.

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From 473bf306f25b05b1516164cbbf7bd0831133275a Mon Sep 17 00:00:00 2001
From: MisterIO <mrio@debian-hell.inferis.org>
Date: Sat, 13 Dec 2008 17:19:27 +0100
Subject: [PATCH] misuse of sizeof

---
 arch/x86/boot/main.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c
index 197421d..ecd87cf 100644
--- a/arch/x86/boot/main.c
+++ b/arch/x86/boot/main.c
@@ -34,8 +34,8 @@ static void copy_boot_params(void)
 	const struct old_cmdline * const oldcmd =
 		(const struct old_cmdline *)OLD_CL_ADDRESS;
 
-	BUILD_BUG_ON(sizeof boot_params != 4096);
-	memcpy(&boot_params.hdr, &hdr, sizeof hdr);
+	BUILD_BUG_ON(sizeof(boot_params) != 4096);
+	memcpy(&boot_params.hdr, &hdr, sizeof(hdr));
 
 	if (!boot_params.hdr.cmd_line_ptr &&
 	    oldcmd->cl_magic == OLD_CL_MAGIC) {
-- 
1.6.0.4

Re: [PATCH] Misuse of sizeof

[Frédéric Weisbecker]

2008/12/13 Giangiacomo Mariotti <giangiacomo.mariotti@gmail.com>:
> IMO there's a bug in the use of sizeof in /arch/x86/boot/main.c, it's
> also a strange style.
>

Hi,

No this is not a bug, sizeof is a unary operator which can be used
with or without parenthesis :-)

Note: don't forget to put your Signed-off-by and some explanations
along your patches.
Also, not all maintainers accept patches as attachment.

Re: [PATCH] Misuse of sizeof

[Giangiacomo Mariotti]

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On 12/13/08, Frédéric Weisbecker <fweisbec@gmail.com> wrote:> 2008/12/13 Giangiacomo Mariotti <giangiacomo.mariotti@gmail.com>:>> IMO there's a bug in the use of sizeof in /arch/x86/boot/main.c, it's>> also a strange style.>>>> Hi,>> No this is not a bug, sizeof is a unary operator which can be used> with or without parenthesis :-)>> Note: don't forget to put your Signed-off-by and some explanations> along your patches.> Also, not all maintainers accept patches as attachment.>You're right, I was wrong.ÿôèº{.nÇ+‰·Ÿ®‰­†+%ŠËÿ±éݶ\x17¥Šwÿº{.nÇ+‰·¥Š{±þG«éÿŠ{ayº\x1dʇڙë,j\a­¢f£¢·hšïêÿ‘êçz_è®\x03(­éšŽŠÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?™¨è­Ú&£ø§~á¶iO•æ¬z·švØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?–I¥

Re: [PATCH] Misuse of sizeof

[Miguel Ojeda]

On Sat, Dec 13, 2008 at 5:31 PM, Giangiacomo Mariotti
<giangiacomo.mariotti@gmail.com> wrote:
> IMO there's a bug in the use of sizeof in /arch/x86/boot/main.c, it's
> also a strange style.
>

It is not a bug. You don't need to use parenthesis when used on
variables. See 6.5.3.4.

Re: [PATCH] Misuse of sizeof

[Gregory Petrosyan]

On Sat, Dec 13, 2008 at 05:31:06PM +0100, Giangiacomo Mariotti wrote:
> IMO there's a bug in the use of sizeof in /arch/x86/boot/main.c, it's
> also a strange style.

> -	BUILD_BUG_ON(sizeof boot_params != 4096);
> -	memcpy(&boot_params.hdr, &hdr, sizeof hdr);
> +	BUILD_BUG_ON(sizeof(boot_params) != 4096);
> +	memcpy(&boot_params.hdr, &hdr, sizeof(hdr));

The 'sizeof xxx' style is perfectly valid.

	Gregory

Re: [PATCH] Misuse of sizeof

[Roland Dreier]

 > IMO there's a bug in the use of sizeof in /arch/x86/boot/main.c, it's
 > also a strange style.

Style is of course a matter of opinion, but sizeof is an operator, not a
function, and as far as I can see, there's no bug in how it is used even
without your patch.

 - R.