linux-kernel - Re: [PATCH] xen-blkfront: use bitmap_set() and bitmap

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]

Message-ID: <20120120160938.GC3959@phenom.dumpdata.com>
Date:	Fri, 20 Jan 2012 11:09:38 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Akinobu Mita <akinobu.mita@...il.com>
Cc:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	Jeremy Fitzhardinge Jeremy Fitzhardinge <jeremy@...p.org>,
	xen-devel@...ts.xensource.com,
	virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH] xen-blkfront: use bitmap_set() and bitmap_clear()

On Sat, Jan 21, 2012 at 12:41:56AM +0900, Akinobu Mita wrote:
> 2012/1/21 Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>:
> > On Sat, Jan 21, 2012 at 12:15:26AM +0900, Akinobu Mita wrote:
> >> Use bitmap_set and bitmap_clear rather than modifying individual bits
> >> in a memory region.
> >>
> >> Signed-off-by: Akinobu Mita <akinobu.mita@...il.com>
> >> Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
> >> Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> >> Cc: xen-devel@...ts.xensource.com
> >> Cc: virtualization@...ts.linux-foundation.org
> >> ---
> >>  drivers/block/xen-blkfront.c |    7 +++----
> >>  1 files changed, 3 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> >> index 2f22874..619868d 100644
> >> --- a/drivers/block/xen-blkfront.c
> >> +++ b/drivers/block/xen-blkfront.c
> >> @@ -43,6 +43,7 @@
> >>  #include <linux/slab.h>
> >>  #include <linux/mutex.h>
> >>  #include <linux/scatterlist.h>
> >> +#include <linux/bitmap.h>
> >>
> >>  #include <xen/xen.h>
> >>  #include <xen/xenbus.h>
> >> @@ -177,8 +178,7 @@ static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
> >>
> >>       spin_lock(&minor_lock);
> >>       if (find_next_bit(minors, end, minor) >= end) {
> >> -             for (; minor < end; ++minor)
> >> -                     __set_bit(minor, minors);
> >> +             bitmap_set(minors, minor, nr);
> >
> > Hm, I would have thought the last argument should have been 'end'?
> 
> 'end' is the index of the last bit to clear.  But the last argument of
> bitmap_clear() is the number of bits to clear.  So I think 'nr' is correct.

Ah, I see it.
> 
> > Did you test this patch with a large amount of minors?
> 
> Sorry I didn't do runtime test.

Please do.
--
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/