linux-kernel - Re: [patch] x86, ptrace: void dopiness

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Date:	Mon, 22 Sep 2008 14:07:43 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	"Metzger, Markus T" <markus.t.metzger@...el.com>
Cc:	markus.t.metzger@...il.com, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, Roland McGrath <roland@...hat.com>,
	"linux-os (Dick Johnson)" <linux-os@...logic.com>
Subject: Re: [patch] x86, ptrace: void dopiness


* Metzger, Markus T <markus.t.metzger@...el.com> wrote:

> >-----Original Message-----
> >From: Ingo Molnar [mailto:mingo@...e.hu] 
> >Sent: Montag, 22. September 2008 13:51
> >To: Metzger, Markus T
> >Cc: markus.t.metzger@...il.com; linux-kernel@...r.kernel.org; 
> >akpm@...ux-foundation.org; Roland McGrath
> >Subject: Re: [patch] x86, ptrace: void dopiness
> >
> >
> >* Markus Metzger <markus.t.metzger@...el.com> wrote:
> >
> >> +++ gits.x86/arch/x86/kernel/ptrace.c	2008-09-19 
> >13:53:02.%N +0200
> >> @@ -738,7 +738,7 @@
> >>  		unsigned int sig = 0;
> >>  
> >>  		/* we ignore the error in case we were not 
> >tracing child */
> >> -		(void)ds_release_bts(child);
> >> +		ds_release_bts(child);
> >
> >hm, here the cast is OK because we actually ignore the return value.
> >
> >> @@ -947,7 +947,7 @@
> >>  	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
> >>  #endif
> >>  #ifdef CONFIG_X86_PTRACE_BTS
> >> -	(void)ds_release_bts(child);
> >> +	ds_release_bts(child);
> >
> >is it right/intentional here?
> 
> The void-cast is intentional in both cases.
> 
> I thought it a question of style, i.e. that we don't want void casts 
> just like we want NULL instead of 0.

ok.

But you could mark ds_release_bts() as a __must_check function, in that 
case the (void) has functional aspects as well: the kernel build will 
complain if a return value is ignored unintentionally.

So i think the code might be fine as-is after all :-/

	Ingo
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