* [S390] cio: Make ccw_dev_id_is_equal() more robust.
@ 2006-12-04 14:56 Martin Schwidefsky
2006-12-04 15:23 ` Josef Sipek
0 siblings, 1 reply; 3+ messages in thread
From: Martin Schwidefsky @ 2006-12-04 14:56 UTC (permalink / raw)
To: linux-kernel, cornelia.huck
From: Cornelia Huck <cornelia.huck@de.ibm.com>
[S390] cio: Make ccw_dev_id_is_equal() more robust.
Using memcmp to compare ccw_dev_id implies that the whole structure (incl.
padding) has always been completely initialized to sane values. Comparing
the structures field by field doesn't make such assumptions.
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
include/asm-s390/cio.h | 5 ++++-
1 files changed, 4 insertions(+), 1 deletion(-)
diff -urpN linux-2.6/include/asm-s390/cio.h linux-2.6-patched/include/asm-s390/cio.h
--- linux-2.6/include/asm-s390/cio.h 2006-12-04 14:50:48.000000000 +0100
+++ linux-2.6-patched/include/asm-s390/cio.h 2006-12-04 14:51:00.000000000 +0100
@@ -278,7 +278,10 @@ struct ccw_dev_id {
static inline int ccw_dev_id_is_equal(struct ccw_dev_id *dev_id1,
struct ccw_dev_id *dev_id2)
{
- return !memcmp(dev_id1, dev_id2, sizeof(struct ccw_dev_id));
+ if ((dev_id1->ssid == dev_id2->ssid) &&
+ (dev_id1->devno == dev_id2->devno))
+ return 1;
+ return 0;
}
extern int diag210(struct diag210 *addr);
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [S390] cio: Make ccw_dev_id_is_equal() more robust.
2006-12-04 14:56 [S390] cio: Make ccw_dev_id_is_equal() more robust Martin Schwidefsky
@ 2006-12-04 15:23 ` Josef Sipek
2006-12-04 15:30 ` Martin Schwidefsky
0 siblings, 1 reply; 3+ messages in thread
From: Josef Sipek @ 2006-12-04 15:23 UTC (permalink / raw)
To: Martin Schwidefsky; +Cc: linux-kernel, cornelia.huck
On Mon, Dec 04, 2006 at 03:56:24PM +0100, Martin Schwidefsky wrote:
...
> diff -urpN linux-2.6/include/asm-s390/cio.h linux-2.6-patched/include/asm-s390/cio.h
> --- linux-2.6/include/asm-s390/cio.h 2006-12-04 14:50:48.000000000 +0100
> +++ linux-2.6-patched/include/asm-s390/cio.h 2006-12-04 14:51:00.000000000 +0100
> @@ -278,7 +278,10 @@ struct ccw_dev_id {
> static inline int ccw_dev_id_is_equal(struct ccw_dev_id *dev_id1,
> struct ccw_dev_id *dev_id2)
> {
> - return !memcmp(dev_id1, dev_id2, sizeof(struct ccw_dev_id));
> + if ((dev_id1->ssid == dev_id2->ssid) &&
> + (dev_id1->devno == dev_id2->devno))
> + return 1;
> + return 0;
> }
Why not just:
return ((dev_id1->ssid == ......) && (...));
?
Josef "Jeff" Sipek.
--
UNIX is user-friendly ... it's just selective about who it's friends are
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [S390] cio: Make ccw_dev_id_is_equal() more robust.
2006-12-04 15:23 ` Josef Sipek
@ 2006-12-04 15:30 ` Martin Schwidefsky
0 siblings, 0 replies; 3+ messages in thread
From: Martin Schwidefsky @ 2006-12-04 15:30 UTC (permalink / raw)
To: Josef Sipek; +Cc: linux-kernel, cornelia.huck
On Mon, 2006-12-04 at 10:23 -0500, Josef Sipek wrote:
> > diff -urpN linux-2.6/include/asm-s390/cio.h linux-2.6-patched/include/asm-s390/cio.h
> > --- linux-2.6/include/asm-s390/cio.h 2006-12-04 14:50:48.000000000 +0100
> > +++ linux-2.6-patched/include/asm-s390/cio.h 2006-12-04 14:51:00.000000000 +0100
> > @@ -278,7 +278,10 @@ struct ccw_dev_id {
> > static inline int ccw_dev_id_is_equal(struct ccw_dev_id *dev_id1,
> > struct ccw_dev_id *dev_id2)
> > {
> > - return !memcmp(dev_id1, dev_id2, sizeof(struct ccw_dev_id));
> > + if ((dev_id1->ssid == dev_id2->ssid) &&
> > + (dev_id1->devno == dev_id2->devno))
> > + return 1;
> > + return 0;
> > }
>
> Why not just:
>
> return ((dev_id1->ssid == ......) && (...));
Yes, why not. It would be a little bit shorter. The compiler probably
won't care and generate the same code..
--
blue skies,
Martin.
Martin Schwidefsky
Linux for zSeries Development & Services
IBM Deutschland Entwicklung GmbH
"Reality continues to ruin my life." - Calvin.
^ permalink raw reply [flat|nested] 3+ messages in thread
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