* [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
@ 2015-10-10 10:56 Jason A. Donenfeld
2015-10-11 19:59 ` Thomas Hellstrom
2016-08-10 12:24 ` Fwd: " Thomas Hellstrom
0 siblings, 2 replies; 14+ messages in thread
From: Jason A. Donenfeld @ 2015-10-10 10:56 UTC (permalink / raw)
To: Dave Airlie, Thomas Hellstrom, linux-kernel; +Cc: Jason A. Donenfeld
On most platforms, there exists this ifdef:
#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
This makes this patch functionally useless. However, on PPC, there is
actually an explicit definition of atomic_inc_not_zero with its own
assembly that is slightly more optimized than atomic_add_unless. So,
this patch changes kref to use atomic_inc_not_zero instead, for PPC and
any future platforms that might provide an explicit implementation.
This also puts this usage of kref more in line with a verbatim reading
of the examples in Paul McKenney's paper [1] in the section titled "2.4
Atomic Counting With Check and Release Memory Barrier", which uses
atomic_inc_not_zero.
[1] http://open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2167.pdf
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
include/linux/kref.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/kref.h b/include/linux/kref.h
index 484604d..83d1f94 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -166,6 +166,6 @@ static inline int kref_put_mutex(struct kref *kref,
*/
static inline int __must_check kref_get_unless_zero(struct kref *kref)
{
- return atomic_add_unless(&kref->refcount, 1, 0);
+ return atomic_inc_not_zero(&kref->refcount);
}
#endif /* _KREF_H_ */
--
2.6.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* Re: [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
2015-10-10 10:56 [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless Jason A. Donenfeld
@ 2015-10-11 19:59 ` Thomas Hellstrom
2016-02-01 21:53 ` Jason A. Donenfeld
2016-12-15 4:58 ` Jason A. Donenfeld
2016-08-10 12:24 ` Fwd: " Thomas Hellstrom
1 sibling, 2 replies; 14+ messages in thread
From: Thomas Hellstrom @ 2015-10-11 19:59 UTC (permalink / raw)
To: Jason A. Donenfeld, Dave Airlie, linux-kernel
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
On 10/10/2015 12:56 PM, Jason A. Donenfeld wrote:
> On most platforms, there exists this ifdef:
>
> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
>
> This makes this patch functionally useless. However, on PPC, there is
> actually an explicit definition of atomic_inc_not_zero with its own
> assembly that is slightly more optimized than atomic_add_unless. So,
> this patch changes kref to use atomic_inc_not_zero instead, for PPC and
> any future platforms that might provide an explicit implementation.
>
> This also puts this usage of kref more in line with a verbatim reading
> of the examples in Paul McKenney's paper [1] in the section titled "2.4
> Atomic Counting With Check and Release Memory Barrier", which uses
> atomic_inc_not_zero.
>
> [1] https://urldefense.proofpoint.com/v2/url?u=http-3A__open-2Dstd.org_jtc1_sc22_wg21_docs_papers_2007_n2167.pdf&d=BQIBAg&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=vpukPkBtpoNQp2IUKuFviOmPNYWVKmen3Jeeu55zmEA&m=z5Nd9sYiJMKiphNjyZp6XT5CbayXMBlcb903f260pDY&s=HEHX3CuXRs2GRRQWuC4Vef6iJMwdilKVRkiZgJpjEpA&e=
>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
> include/linux/kref.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/kref.h b/include/linux/kref.h
> index 484604d..83d1f94 100644
> --- a/include/linux/kref.h
> +++ b/include/linux/kref.h
> @@ -166,6 +166,6 @@ static inline int kref_put_mutex(struct kref *kref,
> */
> static inline int __must_check kref_get_unless_zero(struct kref *kref)
> {
> - return atomic_add_unless(&kref->refcount, 1, 0);
> + return atomic_inc_not_zero(&kref->refcount);
> }
> #endif /* _KREF_H_ */
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
2015-10-11 19:59 ` Thomas Hellstrom
@ 2016-02-01 21:53 ` Jason A. Donenfeld
2016-06-29 22:52 ` Jason A. Donenfeld
2016-12-15 4:58 ` Jason A. Donenfeld
1 sibling, 1 reply; 14+ messages in thread
From: Jason A. Donenfeld @ 2016-02-01 21:53 UTC (permalink / raw)
To: Thomas Hellstrom, Dave Airlie; +Cc: LKML, Paul McKenney
This was positively reviewed but never picked up. Can someone queue
this for rc3?
Thanks,
Jason
On Sun, Oct 11, 2015 at 9:59 PM, Thomas Hellstrom <thellstrom@vmware.com> wrote:
> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
>
>
> On 10/10/2015 12:56 PM, Jason A. Donenfeld wrote:
>> On most platforms, there exists this ifdef:
>>
>> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
>>
>> This makes this patch functionally useless. However, on PPC, there is
>> actually an explicit definition of atomic_inc_not_zero with its own
>> assembly that is slightly more optimized than atomic_add_unless. So,
>> this patch changes kref to use atomic_inc_not_zero instead, for PPC and
>> any future platforms that might provide an explicit implementation.
>>
>> This also puts this usage of kref more in line with a verbatim reading
>> of the examples in Paul McKenney's paper [1] in the section titled "2.4
>> Atomic Counting With Check and Release Memory Barrier", which uses
>> atomic_inc_not_zero.
>>
>> [1] https://urldefense.proofpoint.com/v2/url?u=http-3A__open-2Dstd.org_jtc1_sc22_wg21_docs_papers_2007_n2167.pdf&d=BQIBAg&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=vpukPkBtpoNQp2IUKuFviOmPNYWVKmen3Jeeu55zmEA&m=z5Nd9sYiJMKiphNjyZp6XT5CbayXMBlcb903f260pDY&s=HEHX3CuXRs2GRRQWuC4Vef6iJMwdilKVRkiZgJpjEpA&e=
>>
>> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
>> ---
>> include/linux/kref.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/linux/kref.h b/include/linux/kref.h
>> index 484604d..83d1f94 100644
>> --- a/include/linux/kref.h
>> +++ b/include/linux/kref.h
>> @@ -166,6 +166,6 @@ static inline int kref_put_mutex(struct kref *kref,
>> */
>> static inline int __must_check kref_get_unless_zero(struct kref *kref)
>> {
>> - return atomic_add_unless(&kref->refcount, 1, 0);
>> + return atomic_inc_not_zero(&kref->refcount);
>> }
>> #endif /* _KREF_H_ */
>
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
2016-02-01 21:53 ` Jason A. Donenfeld
@ 2016-06-29 22:52 ` Jason A. Donenfeld
2016-07-01 7:08 ` Thomas Hellstrom
0 siblings, 1 reply; 14+ messages in thread
From: Jason A. Donenfeld @ 2016-06-29 22:52 UTC (permalink / raw)
To: Thomas Hellstrom, Dave Airlie; +Cc: LKML, Paul McKenney
This was positively reviewed by maintainers but never picked up. Can
someone queue this for 4.7 or 4.8?
Thanks,
Jason
On Mon, Feb 1, 2016 at 10:53 PM, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> This was positively reviewed but never picked up. Can someone queue
> this for rc3?
>
> Thanks,
> Jason
>
> On Sun, Oct 11, 2015 at 9:59 PM, Thomas Hellstrom <thellstrom@vmware.com> wrote:
>> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
>>
>>
>> On 10/10/2015 12:56 PM, Jason A. Donenfeld wrote:
>>> On most platforms, there exists this ifdef:
>>>
>>> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
>>>
>>> This makes this patch functionally useless. However, on PPC, there is
>>> actually an explicit definition of atomic_inc_not_zero with its own
>>> assembly that is slightly more optimized than atomic_add_unless. So,
>>> this patch changes kref to use atomic_inc_not_zero instead, for PPC and
>>> any future platforms that might provide an explicit implementation.
>>>
>>> This also puts this usage of kref more in line with a verbatim reading
>>> of the examples in Paul McKenney's paper [1] in the section titled "2.4
>>> Atomic Counting With Check and Release Memory Barrier", which uses
>>> atomic_inc_not_zero.
>>>
>>> [1] https://urldefense.proofpoint.com/v2/url?u=http-3A__open-2Dstd.org_jtc1_sc22_wg21_docs_papers_2007_n2167.pdf&d=BQIBAg&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=vpukPkBtpoNQp2IUKuFviOmPNYWVKmen3Jeeu55zmEA&m=z5Nd9sYiJMKiphNjyZp6XT5CbayXMBlcb903f260pDY&s=HEHX3CuXRs2GRRQWuC4Vef6iJMwdilKVRkiZgJpjEpA&e=
>>>
>>> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
>>> ---
>>> include/linux/kref.h | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/include/linux/kref.h b/include/linux/kref.h
>>> index 484604d..83d1f94 100644
>>> --- a/include/linux/kref.h
>>> +++ b/include/linux/kref.h
>>> @@ -166,6 +166,6 @@ static inline int kref_put_mutex(struct kref *kref,
>>> */
>>> static inline int __must_check kref_get_unless_zero(struct kref *kref)
>>> {
>>> - return atomic_add_unless(&kref->refcount, 1, 0);
>>> + return atomic_inc_not_zero(&kref->refcount);
>>> }
>>> #endif /* _KREF_H_ */
>>
^ permalink raw reply [flat|nested] 14+ messages in thread
* Patch for drm-next WAS Re: [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
2016-06-29 22:52 ` Jason A. Donenfeld
@ 2016-07-01 7:08 ` Thomas Hellstrom
0 siblings, 0 replies; 14+ messages in thread
From: Thomas Hellstrom @ 2016-07-01 7:08 UTC (permalink / raw)
To: Dave Airlie; +Cc: Jason A. Donenfeld, LKML, Paul McKenney, dri-devel
Dave,
Since kref_get_unless_zero() was brought in by drm, could we add this to
drm-next?
Thanks,
Thomas
On 06/30/2016 12:52 AM, Jason A. Donenfeld wrote:
> This was positively reviewed by maintainers but never picked up. Can
> someone queue this for 4.7 or 4.8?
>
> Thanks,
> Jason
>
> On Mon, Feb 1, 2016 at 10:53 PM, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>> This was positively reviewed but never picked up. Can someone queue
>> this for rc3?
>>
>> Thanks,
>> Jason
>>
>> On Sun, Oct 11, 2015 at 9:59 PM, Thomas Hellstrom <thellstrom@vmware.com> wrote:
>>> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
>>>
>>>
>>> On 10/10/2015 12:56 PM, Jason A. Donenfeld wrote:
>>>> On most platforms, there exists this ifdef:
>>>>
>>>> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
>>>>
>>>> This makes this patch functionally useless. However, on PPC, there is
>>>> actually an explicit definition of atomic_inc_not_zero with its own
>>>> assembly that is slightly more optimized than atomic_add_unless. So,
>>>> this patch changes kref to use atomic_inc_not_zero instead, for PPC and
>>>> any future platforms that might provide an explicit implementation.
>>>>
>>>> This also puts this usage of kref more in line with a verbatim reading
>>>> of the examples in Paul McKenney's paper [1] in the section titled "2.4
>>>> Atomic Counting With Check and Release Memory Barrier", which uses
>>>> atomic_inc_not_zero.
>>>>
>>>> [1] https://urldefense.proofpoint.com/v2/url?u=http-3A__open-2Dstd.org_jtc1_sc22_wg21_docs_papers_2007_n2167.pdf&d=BQIBAg&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=vpukPkBtpoNQp2IUKuFviOmPNYWVKmen3Jeeu55zmEA&m=z5Nd9sYiJMKiphNjyZp6XT5CbayXMBlcb903f260pDY&s=HEHX3CuXRs2GRRQWuC4Vef6iJMwdilKVRkiZgJpjEpA&e=
>>>>
>>>> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
>>>> ---
>>>> include/linux/kref.h | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/include/linux/kref.h b/include/linux/kref.h
>>>> index 484604d..83d1f94 100644
>>>> --- a/include/linux/kref.h
>>>> +++ b/include/linux/kref.h
>>>> @@ -166,6 +166,6 @@ static inline int kref_put_mutex(struct kref *kref,
>>>> */
>>>> static inline int __must_check kref_get_unless_zero(struct kref *kref)
>>>> {
>>>> - return atomic_add_unless(&kref->refcount, 1, 0);
>>>> + return atomic_inc_not_zero(&kref->refcount);
>>>> }
>>>> #endif /* _KREF_H_ */
^ permalink raw reply [flat|nested] 14+ messages in thread
* Patch for drm-next WAS Re: [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
@ 2016-07-01 7:08 ` Thomas Hellstrom
0 siblings, 0 replies; 14+ messages in thread
From: Thomas Hellstrom @ 2016-07-01 7:08 UTC (permalink / raw)
To: Dave Airlie; +Cc: Jason A. Donenfeld, Paul McKenney, LKML, dri-devel
Dave,
Since kref_get_unless_zero() was brought in by drm, could we add this to
drm-next?
Thanks,
Thomas
On 06/30/2016 12:52 AM, Jason A. Donenfeld wrote:
> This was positively reviewed by maintainers but never picked up. Can
> someone queue this for 4.7 or 4.8?
>
> Thanks,
> Jason
>
> On Mon, Feb 1, 2016 at 10:53 PM, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>> This was positively reviewed but never picked up. Can someone queue
>> this for rc3?
>>
>> Thanks,
>> Jason
>>
>> On Sun, Oct 11, 2015 at 9:59 PM, Thomas Hellstrom <thellstrom@vmware.com> wrote:
>>> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
>>>
>>>
>>> On 10/10/2015 12:56 PM, Jason A. Donenfeld wrote:
>>>> On most platforms, there exists this ifdef:
>>>>
>>>> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
>>>>
>>>> This makes this patch functionally useless. However, on PPC, there is
>>>> actually an explicit definition of atomic_inc_not_zero with its own
>>>> assembly that is slightly more optimized than atomic_add_unless. So,
>>>> this patch changes kref to use atomic_inc_not_zero instead, for PPC and
>>>> any future platforms that might provide an explicit implementation.
>>>>
>>>> This also puts this usage of kref more in line with a verbatim reading
>>>> of the examples in Paul McKenney's paper [1] in the section titled "2.4
>>>> Atomic Counting With Check and Release Memory Barrier", which uses
>>>> atomic_inc_not_zero.
>>>>
>>>> [1] https://urldefense.proofpoint.com/v2/url?u=http-3A__open-2Dstd.org_jtc1_sc22_wg21_docs_papers_2007_n2167.pdf&d=BQIBAg&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=vpukPkBtpoNQp2IUKuFviOmPNYWVKmen3Jeeu55zmEA&m=z5Nd9sYiJMKiphNjyZp6XT5CbayXMBlcb903f260pDY&s=HEHX3CuXRs2GRRQWuC4Vef6iJMwdilKVRkiZgJpjEpA&e=
>>>>
>>>> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
>>>> ---
>>>> include/linux/kref.h | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/include/linux/kref.h b/include/linux/kref.h
>>>> index 484604d..83d1f94 100644
>>>> --- a/include/linux/kref.h
>>>> +++ b/include/linux/kref.h
>>>> @@ -166,6 +166,6 @@ static inline int kref_put_mutex(struct kref *kref,
>>>> */
>>>> static inline int __must_check kref_get_unless_zero(struct kref *kref)
>>>> {
>>>> - return atomic_add_unless(&kref->refcount, 1, 0);
>>>> + return atomic_inc_not_zero(&kref->refcount);
>>>> }
>>>> #endif /* _KREF_H_ */
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: Patch for drm-next WAS Re: [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
2016-07-01 7:08 ` Thomas Hellstrom
@ 2016-07-12 12:28 ` Daniel Vetter
-1 siblings, 0 replies; 14+ messages in thread
From: Daniel Vetter @ 2016-07-12 12:28 UTC (permalink / raw)
To: Thomas Hellstrom
Cc: Dave Airlie, Jason A. Donenfeld, Paul McKenney, LKML, dri-devel
On Fri, Jul 01, 2016 at 09:08:34AM +0200, Thomas Hellstrom wrote:
> Dave,
>
> Since kref_get_unless_zero() was brought in by drm, could we add this to
> drm-next?
Sure can do, but I can't find the raw patch anywhere (I suck, I know).
Care to resend?
Thanks, Daniel
>
> Thanks,
> Thomas
>
>
> On 06/30/2016 12:52 AM, Jason A. Donenfeld wrote:
> > This was positively reviewed by maintainers but never picked up. Can
> > someone queue this for 4.7 or 4.8?
> >
> > Thanks,
> > Jason
> >
> > On Mon, Feb 1, 2016 at 10:53 PM, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> >> This was positively reviewed but never picked up. Can someone queue
> >> this for rc3?
> >>
> >> Thanks,
> >> Jason
> >>
> >> On Sun, Oct 11, 2015 at 9:59 PM, Thomas Hellstrom <thellstrom@vmware.com> wrote:
> >>> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
> >>>
> >>>
> >>> On 10/10/2015 12:56 PM, Jason A. Donenfeld wrote:
> >>>> On most platforms, there exists this ifdef:
> >>>>
> >>>> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
> >>>>
> >>>> This makes this patch functionally useless. However, on PPC, there is
> >>>> actually an explicit definition of atomic_inc_not_zero with its own
> >>>> assembly that is slightly more optimized than atomic_add_unless. So,
> >>>> this patch changes kref to use atomic_inc_not_zero instead, for PPC and
> >>>> any future platforms that might provide an explicit implementation.
> >>>>
> >>>> This also puts this usage of kref more in line with a verbatim reading
> >>>> of the examples in Paul McKenney's paper [1] in the section titled "2.4
> >>>> Atomic Counting With Check and Release Memory Barrier", which uses
> >>>> atomic_inc_not_zero.
> >>>>
> >>>> [1] https://urldefense.proofpoint.com/v2/url?u=http-3A__open-2Dstd.org_jtc1_sc22_wg21_docs_papers_2007_n2167.pdf&d=BQIBAg&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=vpukPkBtpoNQp2IUKuFviOmPNYWVKmen3Jeeu55zmEA&m=z5Nd9sYiJMKiphNjyZp6XT5CbayXMBlcb903f260pDY&s=HEHX3CuXRs2GRRQWuC4Vef6iJMwdilKVRkiZgJpjEpA&e=
> >>>>
> >>>> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> >>>> ---
> >>>> include/linux/kref.h | 2 +-
> >>>> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/include/linux/kref.h b/include/linux/kref.h
> >>>> index 484604d..83d1f94 100644
> >>>> --- a/include/linux/kref.h
> >>>> +++ b/include/linux/kref.h
> >>>> @@ -166,6 +166,6 @@ static inline int kref_put_mutex(struct kref *kref,
> >>>> */
> >>>> static inline int __must_check kref_get_unless_zero(struct kref *kref)
> >>>> {
> >>>> - return atomic_add_unless(&kref->refcount, 1, 0);
> >>>> + return atomic_inc_not_zero(&kref->refcount);
> >>>> }
> >>>> #endif /* _KREF_H_ */
>
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: Patch for drm-next WAS Re: [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
@ 2016-07-12 12:28 ` Daniel Vetter
0 siblings, 0 replies; 14+ messages in thread
From: Daniel Vetter @ 2016-07-12 12:28 UTC (permalink / raw)
To: Thomas Hellstrom
Cc: Dave Airlie, Jason A. Donenfeld, Paul McKenney, LKML, dri-devel
On Fri, Jul 01, 2016 at 09:08:34AM +0200, Thomas Hellstrom wrote:
> Dave,
>
> Since kref_get_unless_zero() was brought in by drm, could we add this to
> drm-next?
Sure can do, but I can't find the raw patch anywhere (I suck, I know).
Care to resend?
Thanks, Daniel
>
> Thanks,
> Thomas
>
>
> On 06/30/2016 12:52 AM, Jason A. Donenfeld wrote:
> > This was positively reviewed by maintainers but never picked up. Can
> > someone queue this for 4.7 or 4.8?
> >
> > Thanks,
> > Jason
> >
> > On Mon, Feb 1, 2016 at 10:53 PM, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> >> This was positively reviewed but never picked up. Can someone queue
> >> this for rc3?
> >>
> >> Thanks,
> >> Jason
> >>
> >> On Sun, Oct 11, 2015 at 9:59 PM, Thomas Hellstrom <thellstrom@vmware.com> wrote:
> >>> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
> >>>
> >>>
> >>> On 10/10/2015 12:56 PM, Jason A. Donenfeld wrote:
> >>>> On most platforms, there exists this ifdef:
> >>>>
> >>>> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
> >>>>
> >>>> This makes this patch functionally useless. However, on PPC, there is
> >>>> actually an explicit definition of atomic_inc_not_zero with its own
> >>>> assembly that is slightly more optimized than atomic_add_unless. So,
> >>>> this patch changes kref to use atomic_inc_not_zero instead, for PPC and
> >>>> any future platforms that might provide an explicit implementation.
> >>>>
> >>>> This also puts this usage of kref more in line with a verbatim reading
> >>>> of the examples in Paul McKenney's paper [1] in the section titled "2.4
> >>>> Atomic Counting With Check and Release Memory Barrier", which uses
> >>>> atomic_inc_not_zero.
> >>>>
> >>>> [1] https://urldefense.proofpoint.com/v2/url?u=http-3A__open-2Dstd.org_jtc1_sc22_wg21_docs_papers_2007_n2167.pdf&d=BQIBAg&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=vpukPkBtpoNQp2IUKuFviOmPNYWVKmen3Jeeu55zmEA&m=z5Nd9sYiJMKiphNjyZp6XT5CbayXMBlcb903f260pDY&s=HEHX3CuXRs2GRRQWuC4Vef6iJMwdilKVRkiZgJpjEpA&e=
> >>>>
> >>>> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> >>>> ---
> >>>> include/linux/kref.h | 2 +-
> >>>> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/include/linux/kref.h b/include/linux/kref.h
> >>>> index 484604d..83d1f94 100644
> >>>> --- a/include/linux/kref.h
> >>>> +++ b/include/linux/kref.h
> >>>> @@ -166,6 +166,6 @@ static inline int kref_put_mutex(struct kref *kref,
> >>>> */
> >>>> static inline int __must_check kref_get_unless_zero(struct kref *kref)
> >>>> {
> >>>> - return atomic_add_unless(&kref->refcount, 1, 0);
> >>>> + return atomic_inc_not_zero(&kref->refcount);
> >>>> }
> >>>> #endif /* _KREF_H_ */
>
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
^ permalink raw reply [flat|nested] 14+ messages in thread
* Fwd: [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
2015-10-10 10:56 [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless Jason A. Donenfeld
2015-10-11 19:59 ` Thomas Hellstrom
@ 2016-08-10 12:24 ` Thomas Hellstrom
1 sibling, 0 replies; 14+ messages in thread
From: Thomas Hellstrom @ 2016-08-10 12:24 UTC (permalink / raw)
To: Daniel Vetter; +Cc: dri-devel
By request forwarded patch
This is also
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
/Thomas
-------- Forwarded Message --------
Subject: [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
Date: Sat, 10 Oct 2015 12:56:34 +0200
From: Jason A. Donenfeld <Jason@zx2c4.com>
To: Dave Airlie <airlied@redhat.com>, Thomas Hellstrom
<thellstrom@vmware.com>, linux-kernel@vger.kernel.org
CC: Jason A. Donenfeld <Jason@zx2c4.com>
On most platforms, there exists this ifdef:
#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
This makes this patch functionally useless. However, on PPC, there is
actually an explicit definition of atomic_inc_not_zero with its own
assembly that is slightly more optimized than atomic_add_unless. So,
this patch changes kref to use atomic_inc_not_zero instead, for PPC and
any future platforms that might provide an explicit implementation.
This also puts this usage of kref more in line with a verbatim reading
of the examples in Paul McKenney's paper [1] in the section titled "2.4
Atomic Counting With Check and Release Memory Barrier", which uses
atomic_inc_not_zero.
[1] https://urldefense.proofpoint.com/v2/url?u=http-3A__open-2Dstd.org_jtc1_sc22_wg21_docs_papers_2007_n2167.pdf&d=BQIBAg&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=vpukPkBtpoNQp2IUKuFviOmPNYWVKmen3Jeeu55zmEA&m=z5Nd9sYiJMKiphNjyZp6XT5CbayXMBlcb903f260pDY&s=HEHX3CuXRs2GRRQWuC4Vef6iJMwdilKVRkiZgJpjEpA&e=
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
include/linux/kref.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/kref.h b/include/linux/kref.h
index 484604d..83d1f94 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -166,6 +166,6 @@ static inline int kref_put_mutex(struct kref *kref,
*/
static inline int __must_check kref_get_unless_zero(struct kref *kref)
{
- return atomic_add_unless(&kref->refcount, 1, 0);
+ return atomic_inc_not_zero(&kref->refcount);
}
#endif /* _KREF_H_ */
--
2.6.0
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
2015-10-11 19:59 ` Thomas Hellstrom
2016-02-01 21:53 ` Jason A. Donenfeld
@ 2016-12-15 4:58 ` Jason A. Donenfeld
2016-12-15 8:51 ` Christoph Hellwig
1 sibling, 1 reply; 14+ messages in thread
From: Jason A. Donenfeld @ 2016-12-15 4:58 UTC (permalink / raw)
To: Dave Airlie, linux-kernel, Thomas Hellstrom; +Cc: Jason A. Donenfeld
On most platforms, there exists this ifdef:
#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
This makes this patch functionally useless. However, on PPC, there is
actually an explicit definition of atomic_inc_not_zero with its own
assembly that is slightly more optimized than atomic_add_unless. So,
this patch changes kref to use atomic_inc_not_zero instead, for PPC and
any future platforms that might provide an explicit implementation.
This also puts this usage of kref more in line with a verbatim reading
of the examples in Paul McKenney's paper [1] in the section titled "2.4
Atomic Counting With Check and Release Memory Barrier", which uses
atomic_inc_not_zero.
[1] http://open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2167.pdf
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
---
This was reviewed favorably 14 months ago but never picked up.
I'm resubmitting it now in hopes that you can finally queue it
up for 4.10.
include/linux/kref.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/kref.h b/include/linux/kref.h
index e15828fd71f1..62f0a84ae94e 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -133,6 +133,6 @@ static inline int kref_put_mutex(struct kref *kref,
*/
static inline int __must_check kref_get_unless_zero(struct kref *kref)
{
- return atomic_add_unless(&kref->refcount, 1, 0);
+ return atomic_inc_not_zero(&kref->refcount);
}
#endif /* _KREF_H_ */
--
2.11.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* Re: Patch for drm-next WAS Re: [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
2016-07-12 12:28 ` Daniel Vetter
(?)
@ 2016-12-15 4:59 ` Jason A. Donenfeld
-1 siblings, 0 replies; 14+ messages in thread
From: Jason A. Donenfeld @ 2016-12-15 4:59 UTC (permalink / raw)
To: Thomas Hellstrom, Dave Airlie, Jason A. Donenfeld, Paul McKenney,
LKML, dri-devel
On Tue, Jul 12, 2016 at 2:28 PM, Daniel Vetter <daniel@ffwll.ch> wrote:
> Sure can do, but I can't find the raw patch anywhere (I suck, I know).
> Care to resend?
Hey sorry I missed this email requesting the actual patch. I reposted it here:
https://lkml.org/lkml/2016/12/14/814
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
2016-07-12 12:28 ` Daniel Vetter
(?)
(?)
@ 2016-12-15 5:01 ` Jason A. Donenfeld
2016-12-16 7:33 ` Daniel Vetter
-1 siblings, 1 reply; 14+ messages in thread
From: Jason A. Donenfeld @ 2016-12-15 5:01 UTC (permalink / raw)
To: Thomas Hellstrom, dri-devel; +Cc: Jason A. Donenfeld
On most platforms, there exists this ifdef:
#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
This makes this patch functionally useless. However, on PPC, there is
actually an explicit definition of atomic_inc_not_zero with its own
assembly that is slightly more optimized than atomic_add_unless. So,
this patch changes kref to use atomic_inc_not_zero instead, for PPC and
any future platforms that might provide an explicit implementation.
This also puts this usage of kref more in line with a verbatim reading
of the examples in Paul McKenney's paper [1] in the section titled "2.4
Atomic Counting With Check and Release Memory Barrier", which uses
atomic_inc_not_zero.
[1] http://open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2167.pdf
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
---
This was reviewed favorably 14 months ago but never picked up.
I'm resubmitting it now in hopes that you can finally queue it
up for 4.10.
include/linux/kref.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/kref.h b/include/linux/kref.h
index e15828fd71f1..62f0a84ae94e 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -133,6 +133,6 @@ static inline int kref_put_mutex(struct kref *kref,
*/
static inline int __must_check kref_get_unless_zero(struct kref *kref)
{
- return atomic_add_unless(&kref->refcount, 1, 0);
+ return atomic_inc_not_zero(&kref->refcount);
}
#endif /* _KREF_H_ */
--
2.11.0
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
^ permalink raw reply related [flat|nested] 14+ messages in thread
* Re: [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
2016-12-15 4:58 ` Jason A. Donenfeld
@ 2016-12-15 8:51 ` Christoph Hellwig
0 siblings, 0 replies; 14+ messages in thread
From: Christoph Hellwig @ 2016-12-15 8:51 UTC (permalink / raw)
To: Jason A. Donenfeld; +Cc: Dave Airlie, linux-kernel, Thomas Hellstrom
It's also way easier to read using atomic_inc_not_zero..
Reviewed-by: Christoph Hellwig <hch@lst.de>
Not sure you're sending this to the right maintainers, though. You
probably want to include Greg.
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless
2016-12-15 5:01 ` Jason A. Donenfeld
@ 2016-12-16 7:33 ` Daniel Vetter
0 siblings, 0 replies; 14+ messages in thread
From: Daniel Vetter @ 2016-12-16 7:33 UTC (permalink / raw)
To: Jason A. Donenfeld; +Cc: Thomas Hellstrom, dri-devel
On Thu, Dec 15, 2016 at 06:01:10AM +0100, Jason A. Donenfeld wrote:
> On most platforms, there exists this ifdef:
>
> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
>
> This makes this patch functionally useless. However, on PPC, there is
> actually an explicit definition of atomic_inc_not_zero with its own
> assembly that is slightly more optimized than atomic_add_unless. So,
> this patch changes kref to use atomic_inc_not_zero instead, for PPC and
> any future platforms that might provide an explicit implementation.
>
> This also puts this usage of kref more in line with a verbatim reading
> of the examples in Paul McKenney's paper [1] in the section titled "2.4
> Atomic Counting With Check and Release Memory Barrier", which uses
> atomic_inc_not_zero.
>
> [1] http://open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2167.pdf
>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Applied to drm-misc, but for 4.11 since 4.10 is bugfixes only already.
Thanks, Daniel
> ---
> This was reviewed favorably 14 months ago but never picked up.
> I'm resubmitting it now in hopes that you can finally queue it
> up for 4.10.
>
> include/linux/kref.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/kref.h b/include/linux/kref.h
> index e15828fd71f1..62f0a84ae94e 100644
> --- a/include/linux/kref.h
> +++ b/include/linux/kref.h
> @@ -133,6 +133,6 @@ static inline int kref_put_mutex(struct kref *kref,
> */
> static inline int __must_check kref_get_unless_zero(struct kref *kref)
> {
> - return atomic_add_unless(&kref->refcount, 1, 0);
> + return atomic_inc_not_zero(&kref->refcount);
> }
> #endif /* _KREF_H_ */
> --
> 2.11.0
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
^ permalink raw reply [flat|nested] 14+ messages in thread
end of thread, other threads:[~2016-12-16 7:33 UTC | newest]
Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-10-10 10:56 [PATCH] kref: prefer atomic_inc_not_zero to atomic_add_unless Jason A. Donenfeld
2015-10-11 19:59 ` Thomas Hellstrom
2016-02-01 21:53 ` Jason A. Donenfeld
2016-06-29 22:52 ` Jason A. Donenfeld
2016-07-01 7:08 ` Patch for drm-next WAS " Thomas Hellstrom
2016-07-01 7:08 ` Thomas Hellstrom
2016-07-12 12:28 ` Daniel Vetter
2016-07-12 12:28 ` Daniel Vetter
2016-12-15 4:59 ` Jason A. Donenfeld
2016-12-15 5:01 ` Jason A. Donenfeld
2016-12-16 7:33 ` Daniel Vetter
2016-12-15 4:58 ` Jason A. Donenfeld
2016-12-15 8:51 ` Christoph Hellwig
2016-08-10 12:24 ` Fwd: " Thomas Hellstrom
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