* [PATCH 1/1] drivers/s390/cio/qdio_main.c: replace shift loop by ilog2
@ 2014-05-20 16:37 Fabian Frederick
2014-05-20 16:45 ` Joe Perches
2014-06-02 14:41 ` Sebastian Ott
0 siblings, 2 replies; 7+ messages in thread
From: Fabian Frederick @ 2014-05-20 16:37 UTC (permalink / raw)
To: linux-kernel; +Cc: Sebastian Ott, akpm
This is untested.
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
---
drivers/s390/cio/qdio_main.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index 77466c4..8bf9ec1 100644
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -411,15 +411,14 @@ static inline void qdio_stop_polling(struct qdio_q *q)
static inline void account_sbals(struct qdio_q *q, int count)
{
- int pos = 0;
+ int pos;
q->q_stats.nr_sbal_total += count;
if (count == QDIO_MAX_BUFFERS_MASK) {
q->q_stats.nr_sbals[7]++;
return;
}
- while (count >>= 1)
- pos++;
+ pos = ilog2(count);
q->q_stats.nr_sbals[pos]++;
}
--
1.8.4.5
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH 1/1] drivers/s390/cio/qdio_main.c: replace shift loop by ilog2
2014-05-20 16:37 [PATCH 1/1] drivers/s390/cio/qdio_main.c: replace shift loop by ilog2 Fabian Frederick
@ 2014-05-20 16:45 ` Joe Perches
2014-05-21 12:32 ` Sebastian Ott
2014-06-02 14:41 ` Sebastian Ott
1 sibling, 1 reply; 7+ messages in thread
From: Joe Perches @ 2014-05-20 16:45 UTC (permalink / raw)
To: Fabian Frederick; +Cc: linux-kernel, Sebastian Ott, akpm
On Tue, 2014-05-20 at 18:37 +0200, Fabian Frederick wrote:
> This is untested.
[]
> diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
[]
> @@ -411,15 +411,14 @@ static inline void qdio_stop_polling(struct qdio_q *q)
>
> static inline void account_sbals(struct qdio_q *q, int count)
> {
> - int pos = 0;
> + int pos;
>
> q->q_stats.nr_sbal_total += count;
> if (count == QDIO_MAX_BUFFERS_MASK) {
> q->q_stats.nr_sbals[7]++;
> return;
> }
> - while (count >>= 1)
> - pos++;
> + pos = ilog2(count);
What guarantees count > 0 here?
count may be better unsigned.
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 1/1] drivers/s390/cio/qdio_main.c: replace shift loop by ilog2
2014-05-20 16:45 ` Joe Perches
@ 2014-05-21 12:32 ` Sebastian Ott
0 siblings, 0 replies; 7+ messages in thread
From: Sebastian Ott @ 2014-05-21 12:32 UTC (permalink / raw)
To: Joe Perches, Ursula Braun; +Cc: Fabian Frederick, linux-kernel, akpm
On Tue, 20 May 2014, Joe Perches wrote:
> On Tue, 2014-05-20 at 18:37 +0200, Fabian Frederick wrote:
> > This is untested.
> []
> > diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
> []
> > @@ -411,15 +411,14 @@ static inline void qdio_stop_polling(struct qdio_q *q)
> >
> > static inline void account_sbals(struct qdio_q *q, int count)
> > {
> > - int pos = 0;
> > + int pos;
> >
> > q->q_stats.nr_sbal_total += count;
> > if (count == QDIO_MAX_BUFFERS_MASK) {
> > q->q_stats.nr_sbals[7]++;
> > return;
> > }
> > - while (count >>= 1)
> > - pos++;
> > + pos = ilog2(count);
>
> What guarantees count > 0 here?
We would already be screwed when called with count < 0. Ursula, do the
callers assure that count is positive?
Regards,
Sebastian
>
> count may be better unsigned.
>
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/1] drivers/s390/cio/qdio_main.c: replace shift loop by ilog2
2014-05-20 16:37 [PATCH 1/1] drivers/s390/cio/qdio_main.c: replace shift loop by ilog2 Fabian Frederick
2014-05-20 16:45 ` Joe Perches
@ 2014-06-02 14:41 ` Sebastian Ott
2014-06-02 18:17 ` Fabian Frederick
1 sibling, 1 reply; 7+ messages in thread
From: Sebastian Ott @ 2014-06-02 14:41 UTC (permalink / raw)
To: Fabian Frederick; +Cc: linux-kernel, akpm
Hello Fabian,
On Tue, 20 May 2014, Fabian Frederick wrote:
>
> This is untested.
>
> Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Fabian Frederick <fabf@skynet.be>
> ---
> drivers/s390/cio/qdio_main.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
> index 77466c4..8bf9ec1 100644
> --- a/drivers/s390/cio/qdio_main.c
> +++ b/drivers/s390/cio/qdio_main.c
> @@ -411,15 +411,14 @@ static inline void qdio_stop_polling(struct qdio_q *q)
>
> static inline void account_sbals(struct qdio_q *q, int count)
> {
> - int pos = 0;
> + int pos;
>
> q->q_stats.nr_sbal_total += count;
> if (count == QDIO_MAX_BUFFERS_MASK) {
> q->q_stats.nr_sbals[7]++;
> return;
> }
> - while (count >>= 1)
> - pos++;
> + pos = ilog2(count);
> q->q_stats.nr_sbals[pos]++;
> }
>
> --
> 1.8.4.5
>
>
Could you please resend the patch with a better description plus
the change Joe suggested.
Thanks,
Sebastian
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 1/1] drivers/s390/cio/qdio_main.c: replace shift loop by ilog2
2014-06-02 14:41 ` Sebastian Ott
@ 2014-06-02 18:17 ` Fabian Frederick
2014-06-03 7:41 ` Sebastian Ott
0 siblings, 1 reply; 7+ messages in thread
From: Fabian Frederick @ 2014-06-02 18:17 UTC (permalink / raw)
To: Sebastian Ott; +Cc: linux-kernel, akpm
On Mon, 2 Jun 2014 16:41:48 +0200 (CEST)
Sebastian Ott <sebott@linux.vnet.ibm.com> wrote:
> Hello Fabian,
>
> On Tue, 20 May 2014, Fabian Frederick wrote:
> >
> > This is untested.
> >
> > Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Signed-off-by: Fabian Frederick <fabf@skynet.be>
> > ---
> > drivers/s390/cio/qdio_main.c | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
> > index 77466c4..8bf9ec1 100644
> > --- a/drivers/s390/cio/qdio_main.c
> > +++ b/drivers/s390/cio/qdio_main.c
> > @@ -411,15 +411,14 @@ static inline void qdio_stop_polling(struct qdio_q *q)
> >
> > static inline void account_sbals(struct qdio_q *q, int count)
> > {
> > - int pos = 0;
> > + int pos;
> >
> > q->q_stats.nr_sbal_total += count;
> > if (count == QDIO_MAX_BUFFERS_MASK) {
> > q->q_stats.nr_sbals[7]++;
> > return;
> > }
> > - while (count >>= 1)
> > - pos++;
> > + pos = ilog2(count);
> > q->q_stats.nr_sbals[pos]++;
> > }
> >
> > --
> > 1.8.4.5
> >
> >
>
> Could you please resend the patch with a better description plus
> the change Joe suggested.
>
> Thanks,
> Sebastian
Hello Sebastian,
Conclusion of that patch/thread was that callers guarantee count to be > 0
Joe suggested to have unsigned count. Is it what you're talking about ?
Regards,
Fabian
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 1/1] drivers/s390/cio/qdio_main.c: replace shift loop by ilog2
2014-06-02 18:17 ` Fabian Frederick
@ 2014-06-03 7:41 ` Sebastian Ott
0 siblings, 0 replies; 7+ messages in thread
From: Sebastian Ott @ 2014-06-03 7:41 UTC (permalink / raw)
To: Fabian Frederick; +Cc: linux-kernel, akpm
On Mon, 2 Jun 2014, Fabian Frederick wrote:
> On Mon, 2 Jun 2014 16:41:48 +0200 (CEST)
> Sebastian Ott <sebott@linux.vnet.ibm.com> wrote:
>
> > Hello Fabian,
> >
> > On Tue, 20 May 2014, Fabian Frederick wrote:
> > >
> > > This is untested.
> > >
> > > Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
> > > Cc: Andrew Morton <akpm@linux-foundation.org>
> > > Signed-off-by: Fabian Frederick <fabf@skynet.be>
> > > ---
> > > drivers/s390/cio/qdio_main.c | 5 ++---
> > > 1 file changed, 2 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
> > > index 77466c4..8bf9ec1 100644
> > > --- a/drivers/s390/cio/qdio_main.c
> > > +++ b/drivers/s390/cio/qdio_main.c
> > > @@ -411,15 +411,14 @@ static inline void qdio_stop_polling(struct qdio_q *q)
> > >
> > > static inline void account_sbals(struct qdio_q *q, int count)
> > > {
> > > - int pos = 0;
> > > + int pos;
> > >
> > > q->q_stats.nr_sbal_total += count;
> > > if (count == QDIO_MAX_BUFFERS_MASK) {
> > > q->q_stats.nr_sbals[7]++;
> > > return;
> > > }
> > > - while (count >>= 1)
> > > - pos++;
> > > + pos = ilog2(count);
> > > q->q_stats.nr_sbals[pos]++;
> > > }
> > >
> > > --
> > > 1.8.4.5
> > >
> > >
> >
> > Could you please resend the patch with a better description plus
> > the change Joe suggested.
> >
> > Thanks,
> > Sebastian
>
> Hello Sebastian,
> Conclusion of that patch/thread was that callers guarantee count to be > 0
Correct.
> Joe suggested to have unsigned count. Is it what you're talking about ?
Yes.
Regards,
Sebastian
^ permalink raw reply [flat|nested] 7+ messages in thread
[parent not found: <OF57E68FFD.38663B1A-ONC1257CE0.00383C6B-C1257CE0.0038457A@de.ibm.com>]
* Re: [PATCH 1/1] drivers/s390/cio/qdio_main.c: replace shift loop by ilog2
[not found] <OF57E68FFD.38663B1A-ONC1257CE0.00383C6B-C1257CE0.0038457A@de.ibm.com>
@ 2014-05-22 10:22 ` Ursula Braun
0 siblings, 0 replies; 7+ messages in thread
From: Ursula Braun @ 2014-05-22 10:22 UTC (permalink / raw)
To: Sebastian Ott
Cc: Joe Perches, ursula.braun, Fabian Frederick, linux-kernel, akpm
yes, the callers guarantee that count > 0 here.
Regards, Ursula Braun
On Thu, 2014-05-22 at 12:14 +0200, Ursula Braun1 wrote:
> From: Sebastian Ott <sebott@linux.vnet.ibm.com>
> To: Joe Perches <joe@perches.com>, Ursula
> Braun1/Germany/IBM@IBMDE,
> Cc: Fabian Frederick <fabf@skynet.be>, linux-kernel
> <linux-kernel@vger.kernel.org>, akpm <akpm@linux-foundation.org>
> Date: 21/05/2014 14:32
> Subject: Re: [PATCH 1/1] drivers/s390/cio/qdio_main.c: replace
> shift loop by ilog2
>
> ______________________________________________________________________
>
>
>
> On Tue, 20 May 2014, Joe Perches wrote:
> > On Tue, 2014-05-20 at 18:37 +0200, Fabian Frederick wrote:
> > > This is untested.
> > []
> > > diff --git a/drivers/s390/cio/qdio_main.c
> b/drivers/s390/cio/qdio_main.c
> > []
> > > @@ -411,15 +411,14 @@ static inline void qdio_stop_polling(struct
> qdio_q *q)
> > >
> > > static inline void account_sbals(struct qdio_q *q, int count)
> > > {
> > > - int pos = 0;
> > > + int pos;
> > >
> > > q->q_stats.nr_sbal_total += count;
> > > if (count == QDIO_MAX_BUFFERS_MASK) {
> > > q->q_stats.nr_sbals[7]++;
> > > return;
> > > }
> > > - while (count >>= 1)
> > > - pos++;
> > > + pos = ilog2(count);
> >
> > What guarantees count > 0 here?
>
> We would already be screwed when called with count < 0. Ursula, do the
> callers assure that count is positive?
>
> Regards,
> Sebastian
> >
> > count may be better unsigned.
> >
> >
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2014-06-03 7:41 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
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2014-05-20 16:37 [PATCH 1/1] drivers/s390/cio/qdio_main.c: replace shift loop by ilog2 Fabian Frederick
2014-05-20 16:45 ` Joe Perches
2014-05-21 12:32 ` Sebastian Ott
2014-06-02 14:41 ` Sebastian Ott
2014-06-02 18:17 ` Fabian Frederick
2014-06-03 7:41 ` Sebastian Ott
[not found] <OF57E68FFD.38663B1A-ONC1257CE0.00383C6B-C1257CE0.0038457A@de.ibm.com>
2014-05-22 10:22 ` Ursula Braun
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