From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756628AbYKQJrr (ORCPT ); Mon, 17 Nov 2008 04:47:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752805AbYKQJri (ORCPT ); Mon, 17 Nov 2008 04:47:38 -0500 Received: from pasmtpa.tele.dk ([80.160.77.114]:34566 "EHLO pasmtpA.tele.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752607AbYKQJri (ORCPT ); Mon, 17 Nov 2008 04:47:38 -0500 Date: Mon, 17 Nov 2008 10:45:51 +0100 From: Jens Axboe To: Ingo Molnar Cc: Linus Torvalds , Tejun Heo , Arjan van de Ven , Hugh Dickins , linux-kernel@vger.kernel.org, akpm@linux-foundation.org Subject: Re: [PATCH] Fix kunmap() argument in sg_miter_stop Message-ID: <20081117094551.GI26778@kernel.dk> References: <20081115123916.0d83a89e@infradead.org> <491FACC3.1050202@gmail.com> <20081117081117.GD26778@kernel.dk> <20081117082201.GB24603@elte.hu> <20081117083022.GE26778@kernel.dk> <20081117085046.GE28786@elte.hu> <20081117085807.GF26778@kernel.dk> <20081117093425.GG26778@kernel.dk> <20081117094147.GJ28786@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081117094147.GJ28786@elte.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 17 2008, Ingo Molnar wrote: > > * Jens Axboe wrote: > > > On Mon, Nov 17 2008, Jens Axboe wrote: > > > On Mon, Nov 17 2008, Ingo Molnar wrote: > > > > > > > > * Jens Axboe wrote: > > > > > > > > > On Mon, Nov 17 2008, Ingo Molnar wrote: > > > > > > > > > > > > * Jens Axboe wrote: > > > > > > > > > > > > > +#define kunmap(p) \ > > > > > > > + do { \ > > > > > > > + struct page *__p; \ > > > > > > > + (void) (&__p == &(p)); \ > > > > > > > + __kunmap(p); \ > > > > > > > + } while (0) > > > > > > > + > > > > > > > +#define kunmap_atomic(a, t) \ > > > > > > > + do { \ > > > > > > > + void *__p; \ > > > > > > > + (void) (&__p == &(a)); \ > > > > > > > + __kunmap_atomic(a, t); \ > > > > > > > + } while (0) > > > > > > > > > > > > Agreed - but please use the typecheck() primitive. (linux/typecheck.h) > > > > > > > > > > Neat, didn't know about that, thanks. > > > > > > > > and ack on your patch obviously. Feel free to push it via the block > > > > tree straight away, it doesnt collide with anything pending in the x86 > > > > tree. > > > > > > > > Acked-by: Ingo Molnar > > > > > > The kunmap() bit is easy to do as I mentioned, but the kunmap_atomic() > > > gets a bit more ugly. Lots of users can just be switched to void * > > > types, but some get ugly like: > > > > > > static struct page **shmem_dir_map(struct page *page) > > > return (struct page **)kmap_atomic(page, KM_USER0); > > > } > > > > > > -static inline void shmem_dir_unmap(struct page **dir) > > > +static inline void shmem_dir_unmap(void *dir) > > > { > > > kunmap_atomic(dir, KM_USER0); > > > } > > > > > > and others again like fs/exec.c:remove_arg_zero() would really like to > > > use a char * type since it dereferences it. > > > > > > I think the kunmap_atomic() change it the most needed part of the patch, > > > but I don't think it can come for free (eg, we have to add variable to > > > the above function). > > > > OK, (void *) cast works fine when I fixed it. Here's a normal build diff > > to show approximately how bad it is. I expected it to be worse, so it > > looks quite doable I think. > > hm: > > 32 files changed, 89 insertions(+), 62 deletions(-) > > regarding churn it looks a bit like on the high side. OTOH it's > trivial, most of the churn is spread-out in various architectures, and > it can catch real bugs so i'm still acking it. > > Could you please send the patch with a full changelog? I've Cc:-ed > Linus and Andrew - please let us know if you think that this too much > churn for -rc6. I'll send out a new version when I've done a full build, to avoid introducing new warnings. And I'll do that as a proper patch with SOB and description, etc. -- Jens Axboe