From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx171.postini.com [74.125.245.171]) by kanga.kvack.org (Postfix) with SMTP id C0F556B0044 for ; Sat, 24 Mar 2012 12:22:58 -0400 (EDT) Received: by bkwq16 with SMTP id q16so4408388bkw.14 for ; Sat, 24 Mar 2012 09:22:56 -0700 (PDT) Date: Sat, 24 Mar 2012 20:21:52 +0400 From: Anton Vorontsov Subject: Re: [PATCH 10/10] oom: Make find_lock_task_mm() sparse-aware Message-ID: <20120324162151.GA3640@lizard> References: <20120324102609.GA28356@lizard> <20120324103127.GJ29067@lizard> <1332593574.16159.31.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1332593574.16159.31.camel@twins> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Andrew Morton , Oleg Nesterov , Russell King , Mike Frysinger , Benjamin Herrenschmidt , Richard Weinberger , Paul Mundt , KOSAKI Motohiro , John Stultz , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, uclinux-dist-devel@blackfin.uclinux.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net, linux-mm@kvack.org, Linus Torvalds On Sat, Mar 24, 2012 at 01:52:54PM +0100, Peter Zijlstra wrote: [...] > > p.s. I know Peter Zijlstra detest the __cond_lock() stuff, but untill > > we have anything better in sparse, let's use it. This particular > > patch helped me to detect one bug that I myself made during > > task->mm fixup series. So, it is useful. > > Yeah, so Nacked-by: Peter Zijlstra > > Also, why didn't lockdep catch it? Because patch authors test their patches on architectures they own (well, sometimes I do check patches on exotic architectures w/ qemu, but it is less convenient than just build/sparse-test the patch w/ a cross compiler). And since lockdep is a runtime checker, it is not very useful. Sparse is a build-time checker, so it is even better in the sense that it is able to catch bugs even in code that is executed rarely. > Fix sparse already instead of smearing ugly all over. Just wonder how do you see the feature implemented? Something like this? #define __ret_cond_locked(l, c) __attribute__((ret_cond_locked(l, c))) #define __ret_value __attribute__((ret_value)) #define __ret_locked_nonnull(l) __ret_cond_locked(l, __ret_value); extern struct task_struct *find_lock_task_mm(struct task_struct *p) __ret_locked_nonnull(&__ret_value->alloc_lock); Thanks, -- Anton Vorontsov Email: cbouatmailru@gmail.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org