From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH] sg: disable interrupts inside sg_copy_buffer Date: Fri, 12 Sep 2008 08:05:46 +0200 Message-ID: <20080912060544.GF20055@kernel.dk> References: <20080911235215U.fujita.tomonori@lab.ntt.co.jp> <20080911163302.GV20055@kernel.dk> <20080912110422A.fujita.tomonori@lab.ntt.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from pasmtpb.tele.dk ([80.160.77.98]:56839 "EHLO pasmtpB.tele.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751220AbYILGFt (ORCPT ); Fri, 12 Sep 2008 02:05:49 -0400 Content-Disposition: inline In-Reply-To: <20080912110422A.fujita.tomonori@lab.ntt.co.jp> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: FUJITA Tomonori Cc: linux-scsi@vger.kernel.org, James.Bottomley@HansenPartnership.com On Fri, Sep 12 2008, FUJITA Tomonori wrote: > On Thu, 11 Sep 2008 18:33:03 +0200 > Jens Axboe wrote: > > > On Thu, Sep 11 2008, FUJITA Tomonori wrote: > > > The callers of sg_copy_buffer must disable interrupts before calling > > > it (since it uses kmap_atomic). Some callers use it on > > > interrupt-disabled code but some need to take the trouble to disable > > > interrupts just for this. No wonder they forget about it and we hit a > > > bug like: > > > > > > http://bugzilla.kernel.org/show_bug.cgi?id=11529 > > > > > > James said that it might be better to disable interrupts inside the > > > function rather than risk the callers getting it wrong. > > > > > > Signed-off-by: FUJITA Tomonori > > > --- > > > lib/scatterlist.c | 5 +++++ > > > 1 files changed, 5 insertions(+), 0 deletions(-) > > > > > > diff --git a/lib/scatterlist.c b/lib/scatterlist.c > > > index 876ba6d..dd52cd5 100644 > > > --- a/lib/scatterlist.c > > > +++ b/lib/scatterlist.c > > > @@ -422,6 +422,9 @@ static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, > > > { > > > unsigned int offset = 0; > > > struct sg_mapping_iter miter; > > > + unsigned long flags; > > > + > > > + local_irq_save(flags); > > > > > > sg_miter_start(&miter, sgl, nents, SG_MITER_ATOMIC); > > > > > > @@ -442,6 +445,8 @@ static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, > > > > > > sg_miter_stop(&miter); > > > > > > + local_irq_restore(flags); > > > + > > > return offset; > > > } > > > > Agreed and applied. > > Jens, this won't go to 2.6.27 (goes to 2.6.28)? > > If so, I need to ask James to apply this workaround to 2.6.27: > > http://marc.info/?l=linux-scsi&m=122106973807028&w=2 It will go into 2.6.27, it's already upstream since ~10 hours or so. -- Jens Axboe