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SubjectRe: [PATCH] xen-blkfront: use bitmap_set() and bitmap_clear()
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@gmail.com>
> Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: xen-devel@lists.xensource.com
> Cc: virtualization@lists.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'?

Did you test this patch with a large amount of minors?

> rc = 0;
> } else
> rc = -EBUSY;
> @@ -193,8 +193,7 @@ static void xlbd_release_minors(unsigned int minor, unsigned int nr)
>
> BUG_ON(end > nr_minors);
> spin_lock(&minor_lock);
> - for (; minor < end; ++minor)
> - __clear_bit(minor, minors);
> + bitmap_clear(minors, minor, nr);

Ditto.
> spin_unlock(&minor_lock);
> }
>
> --
> 1.7.4.4
>
> --
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