Re: Introduce down_killable()

Re: Introduce down_killable()

[Andrew Morton]

On Fri, 18 Apr 2008 17:05:06 GMT
Linux Kernel Mailing List <linux-kernel@vger.kernel.org> wrote:

> --- a/kernel/semaphore.c
> +++ b/kernel/semaphore.c
> @@ -34,6 +34,7 @@
>  
>  static noinline void __down(struct semaphore *sem);
>  static noinline int __down_interruptible(struct semaphore *sem);
> +static noinline int __down_killable(struct semaphore *sem);
>  static noinline void __up(struct semaphore *sem);

What is the reason for all the noinlines in this file?

Something to do with getting proper wchan output?  I guess it doesn't hurt
from a documentation POV, but did you find that it was actually necessary?

IOW: is gcc now capable of secretly inlining functions which are defined
further ahead in the compilation unit?


(did you actually "test" the wchan stuff, btw?)

Re: Introduce down_killable()

[Matthew Wilcox]

On Fri, Apr 18, 2008 at 03:34:55PM -0700, Andrew Morton wrote:
> On Fri, 18 Apr 2008 17:05:06 GMT
> Linux Kernel Mailing List <linux-kernel@vger.kernel.org> wrote:
> 
> > --- a/kernel/semaphore.c
> > +++ b/kernel/semaphore.c
> > @@ -34,6 +34,7 @@
> >  
> >  static noinline void __down(struct semaphore *sem);
> >  static noinline int __down_interruptible(struct semaphore *sem);
> > +static noinline int __down_killable(struct semaphore *sem);
> >  static noinline void __up(struct semaphore *sem);
> 
> What is the reason for all the noinlines in this file?

Copied from kernel/mutex.c ;-)

The reason is to make sure that __down_interruptible (et al) are
out-of-line from down_interruptible, and that __down_common is inlined
into __down_interruptible().

> Something to do with getting proper wchan output?  I guess it doesn't hurt
> from a documentation POV, but did you find that it was actually necessary?
> 
> IOW: is gcc now capable of secretly inlining functions which are defined
> further ahead in the compilation unit?

With -funit-at-a-time, I believe it is capable of that.

> (did you actually "test" the wchan stuff, btw?)

I tested that wchan still produces the right output, yes.

-- 
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