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From: Andreas Schwab <schwab@linux-m68k.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>,
	Christoph Hellwig <hch@infradead.org>,
	Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>,
	Vitaly Mayatskikh <v.mayatskih@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Roland McGrath <roland@redhat.com>,
	linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: Q: put_user_try & co (Was: [PATCH 1/5] Split wait_noreap_copyout())
Date: Wed, 20 May 2009 23:14:25 +0200	[thread overview]
Message-ID: <m2my97wk7i.fsf@igel.home> (raw)
In-Reply-To: <20090520190312.GA32333@redhat.com> (Oleg Nesterov's message of "Wed, 20 May 2009 21:03:12 +0200")

Oleg Nesterov <oleg@redhat.com> writes:

> Pseudo-code:
>
> 	#define put_user_try				\
> 		do {					\
> 			__label__  __efault_label;	\
>
>
> 	#define put_user_catch(err)			\
> 			err = 0;			\
> 			if (0) {			\
> 			__efault_label:			\
> 				err = -EFAULT;		\
> 			}				\
> 		while (0)
> 		
>
> 	#define __put_user_asm_ex(...)				\
> 		asm volatile(					\
> 			"1:	mov ..."			\
> 			_ASM_EXTABLE(1b, &__efault_label)	\
> 		     	: : ...)

The address of local labels can only be used in connection with computed
gotos, otherwise you get unspecified results.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

  parent reply	other threads:[~2009-05-20 21:14 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-11 10:12 [PATCH 0/5] wait_task_* cleanups Vitaly Mayatskikh
2009-05-11 10:12 ` [PATCH 1/5] Split wait_noreap_copyout() Vitaly Mayatskikh
2009-05-11 10:20   ` Ingo Molnar
2009-05-11 11:20     ` Vitaly Mayatskikh
2009-05-11 12:04   ` Christoph Hellwig
2009-05-11 12:17     ` Ingo Molnar
2009-05-11 20:47       ` Vitaly Mayatskikh
2009-05-11 21:04         ` Ingo Molnar
2009-05-20 19:03       ` Q: put_user_try & co (Was: [PATCH 1/5] Split wait_noreap_copyout()) Oleg Nesterov
2009-05-20 20:11         ` Roland McGrath
2009-05-20 20:56           ` H. Peter Anvin
2009-05-21 13:42           ` Oleg Nesterov
2009-05-20 21:14         ` Andreas Schwab [this message]
2009-05-11 12:17     ` [PATCH 1/5] Split wait_noreap_copyout() Vitaly Mayatskikh
2009-05-11 10:12 ` [PATCH 2/5] Use wait_copyout() in wait_task_stopped() Vitaly Mayatskikh
2009-05-11 10:12 ` [PATCH 3/5] Use wait_copyout() in do_wait() Vitaly Mayatskikh
2009-05-11 10:12 ` [PATCH 4/5] Use wait_copyout() in wait_task_zombie() Vitaly Mayatskikh
2009-05-11 10:12 ` [PATCH 5/5] Use wait_copyout() in wait_task_continued() Vitaly Mayatskikh

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