linux-kernel - Re: [PATCH v2 15/26] block: Add bio_copy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 20 Sep 2012 17:09:45 -0700
From:	Kent Overstreet <koverstreet@...gle.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	linux-bcache@...r.kernel.org, linux-kernel@...r.kernel.org,
	dm-devel@...hat.com, axboe@...nel.dk, neilb@...e.de
Subject: Re: [PATCH v2 15/26] block: Add bio_copy_data()

On Thu, Sep 20, 2012 at 05:06:32PM -0700, Tejun Heo wrote:
> Hello,
> 
> On Mon, Sep 10, 2012 at 05:22:26PM -0700, Kent Overstreet wrote:
> > +void bio_copy_data(struct bio *dst, struct bio *src)
> > +{
> ...
> > +		src_p = kmap_atomic(src_bv->bv_page);
> > +		dst_p = kmap_atomic(dst_bv->bv_page);
> > +
> > +		memcpy(dst_p + dst_bv->bv_offset,
> > +		       src_p + src_bv->bv_offset,
> > +		       bytes);
> > +
> > +		kunmap_atomic(dst_p);
> > +		kunmap_atomic(src_p);
> 
> Wrap these in preempt_disable/enable() to allow the function to be
> called from any context?

I checked the implementation of kmap_atomic(), it already does
preempt_disable() so it's safe in process context - if I understand
correctly it needs local_irq_save()/restore() to be safe in any context
and I figured calling this from irq context is not the norm so that
should be the caller's responsibility.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/