Re: [RFC|PATCH] Compile time printk verbosity

[Mike Frysinger <vapier.adi@gmail.com>]

On Wed, Sep 2, 2009 at 05:47, Marc Andre Tanner wrote:
> On Wed, Sep 02, 2009 at 05:11:12AM -0400, Mike Frysinger wrote:
>> On Wed, Sep 2, 2009 at 04:57, Marc Andre Tanner wrote:
>> > On Tue, Sep 01, 2009 at 07:37:27PM -0400, Mike Frysinger wrote:
>> >> On Tue, Sep 1, 2009 at 18:31, Marc Andre Tanner wrote:
>> >> > This series adds a configuration option to selectively compile out
>> >> > printk message strings based on a verbosity level.
>> >> >
>> >> > This works by wrapping printk with a macro which evaluates to a
>> >> > constant if condition which the compiler will be able to optimize
>> >> > out.
>> >> >
>> >> > However because printk might be wrapped by a macro it no longer has
>> >> > a return value. This means that constructs like the following ones
>> >> > don't work:
>> >> >
>> >> >   ((void)(SOME_RANDOM_DEBUG_FLAG && printk(...));
>> >> >
>> >> >   some_random_variable = printk(...);
>> >> >
>> >> > Therefore printk_unfiltered is introduced which is just an alias
>> >> > to the standard printk function but not wrapped by a macro.
>> >>
>> >> why dont you return 0 if it gets optimized away ?  then you wont have
>> >> to screw with external code at all and things "just work".
>> >
>> > This won't work because it would for example also return from functions
>> > which call printk but aren't checking for the return value (which is
>> > the common case).
>>
>> why would it matter ?
>>
>> ({
>>     int __printk_ret = 0;
>>     if (crazy stuff you're adding)
>>         __printk_ret = printk(.....);
>>     __printk_ret;
>> })
>
> Yes I missunderstood your "return 0" statement in the first mail.
> The same effect could also be achieved by:
>
> ((crazy stuff) ? printk(...) : 0;

while true, i thought your (crazy stuff) pretty verbose and the
tertiary operator might get swallowed in the noise.  not that it
matters that much to me as this is now a pure style choice ... your
patch, you pick.
-mike