On Wed, Feb 12, 2014 at 9:59 PM, Joe Perches <joe@xxxxxxxxxxx> wrote:
> On Wed, 2014-02-12 at 21:13 -0500, Patrick Palka wrote:
>> When !defined(CONFIG_EXT4_DEBUG), mb_debug() should be defined as an
>> empty do-while statement so as to suppress the following compiler
>> warning:
>
> Hello Patrick.
>
>> fs/ext4/mballoc.c: In function 'ext4_mb_cleanup_pa':
>> fs/ext4/mballoc.c:2659:47: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
>> mb_debug(1, "mballoc: %u PAs left\n", count);
>> ---
>> diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
> []
>> @@ -48,7 +48,7 @@ extern ushort ext4_mballoc_debug;
>> } \
>> } while (0)
>> #else
>> -#define mb_debug(n, fmt, a...)
>> +#define mb_debug(n, fmt, a...) do { } while (0)
>
> Ideally, this section should be something like below
> so the !CONFIG_EXT4_DEBUG case still verifies that
> the format and argument types match.
>
> This can help avoid people adding debug statements but
> not compiling with the proper CONFIG_<foo> variable set.
>
> ---
>
> #ifdef CONFIG_EXT4_DEBUG
> extern ushort ext4_mballoc_debug;
>
> #define mb_debug(n, fmt, ...) \
> do { \
> if ((n) <= ext4_mballoc_debug) \
> pr_debug(fmt, ##__VA_ARGS__); \
> } \
> } while (0)
> #else
> #define mb_debug(n, fmt, ...) \
> no_printk(KERN_DEBUG fmt, ##__VA_ARGS__)
> #endif
>
>
Hi Joe,
Thanks! I was not aware of that idiom. It makes a good amount of
sense. I'm going to send a revised version of the patch shortly.
Patrick
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