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[v2] dm-switch: Remove unnecessary condition in conditional

Message ID 1446058461-26298-1-git-send-email-kusumi.tomohiro@gmail.com (mailing list archive)
State Accepted, archived
Delegated to: Mike Snitzer
Headers show

Commit Message

Tomohiro Kusumi Oct. 28, 2015, 6:54 p.m. UTC 
> 2015-10-28 8:03 GMT+09:00 Mikulas Patocka:
> On Wed, 28 Oct 2015, Tomohiro Kusumi wrote:
>
> > It's always (sctx->nr_regions == nr_regions) considering
> > the assignment right before this conditional, and this
> > function is only used by .ctr.
>
> The variable sctx->nr_regions has type unsigned long and the variable
> nr_regions has type sector_t.
>
> Thus the variables may be different when overflow happens.
>
> It could be changed to "if (nr_regions >= ULONG_MAX)".

Sorry about that.
Changed the conditional to "if (nr_regions >= ULONG_MAX)",
and brought the assignment of nr_regions after sector_div()
and the sanity check which looks more sane.

Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
---
 drivers/md/dm-switch.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

Comments

Mikulas Patocka Oct. 29, 2015, 4:15 p.m. UTC | #1 
On Thu, 29 Oct 2015, Tomohiro Kusumi wrote:

> > 2015-10-28 8:03 GMT+09:00 Mikulas Patocka:
> > On Wed, 28 Oct 2015, Tomohiro Kusumi wrote:
> >
> > > It's always (sctx->nr_regions == nr_regions) considering
> > > the assignment right before this conditional, and this
> > > function is only used by .ctr.
> >
> > The variable sctx->nr_regions has type unsigned long and the variable
> > nr_regions has type sector_t.
> >
> > Thus the variables may be different when overflow happens.
> >
> > It could be changed to "if (nr_regions >= ULONG_MAX)".
> 
> Sorry about that.
> Changed the conditional to "if (nr_regions >= ULONG_MAX)",
> and brought the assignment of nr_regions after sector_div()
> and the sanity check which looks more sane.
> 
> Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
> Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>

Acked-by: Mikulas Patocka <mpatocka@redhat.com>

> ---
>  drivers/md/dm-switch.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/md/dm-switch.c b/drivers/md/dm-switch.c
> index 50fca46..e1b6722 100644
> --- a/drivers/md/dm-switch.c
> +++ b/drivers/md/dm-switch.c
> @@ -99,11 +99,11 @@ static int alloc_region_table(struct dm_target *ti, unsigned nr_paths)
>  	if (sector_div(nr_regions, sctx->region_size))
>  		nr_regions++;
>  
> -	sctx->nr_regions = nr_regions;
> -	if (sctx->nr_regions != nr_regions || sctx->nr_regions >= ULONG_MAX) {
> +	if (nr_regions >= ULONG_MAX) {
>  		ti->error = "Region table too large";
>  		return -EINVAL;
>  	}
> +	sctx->nr_regions = nr_regions;
>  
>  	nr_slots = nr_regions;
>  	if (sector_div(nr_slots, sctx->region_entries_per_slot))
> -- 
> 1.7.1
> 

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diff mbox

Patch

diff --git a/drivers/md/dm-switch.c b/drivers/md/dm-switch.c
index 50fca46..e1b6722 100644
--- a/drivers/md/dm-switch.c
+++ b/drivers/md/dm-switch.c
@@ -99,11 +99,11 @@  static int alloc_region_table(struct dm_target *ti, unsigned nr_paths)
 	if (sector_div(nr_regions, sctx->region_size))
 		nr_regions++;
 
-	sctx->nr_regions = nr_regions;
-	if (sctx->nr_regions != nr_regions || sctx->nr_regions >= ULONG_MAX) {
+	if (nr_regions >= ULONG_MAX) {
 		ti->error = "Region table too large";
 		return -EINVAL;
 	}
+	sctx->nr_regions = nr_regions;
 
 	nr_slots = nr_regions;
 	if (sector_div(nr_slots, sctx->region_entries_per_slot))