[PATCH net-next v1] net: page_pool: factor out page_pool recycle check

[PATCH net-next v1] net: page_pool: factor out page_pool recycle check

[Mina Almasry]

The check is duplicated in 2 places, factor it out into a common helper.

Signed-off-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com>
---
 net/core/page_pool.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index d706fe5548df..dd364d738c00 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -657,6 +657,11 @@ static bool page_pool_recycle_in_cache(struct page *page,
 	return true;
 }
 
+static bool __page_pool_page_can_be_recycled(const struct page *page)
+{
+	return page_ref_count(page) == 1 && !page_is_pfmemalloc(page);
+}
+
 /* If the page refcnt == 1, this will try to recycle the page.
  * if PP_FLAG_DMA_SYNC_DEV is set, we'll try to sync the DMA area for
  * the configured size min(dma_sync_size, pool->max_len).
@@ -678,7 +683,7 @@ __page_pool_put_page(struct page_pool *pool, struct page *page,
 	 * page is NOT reusable when allocated when system is under
 	 * some pressure. (page_is_pfmemalloc)
 	 */
-	if (likely(page_ref_count(page) == 1 && !page_is_pfmemalloc(page))) {
+	if (likely(__page_pool_page_can_be_recycled(page))) {
 		/* Read barrier done in page_ref_count / READ_ONCE */
 
 		if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
@@ -793,7 +798,7 @@ static struct page *page_pool_drain_frag(struct page_pool *pool,
 	if (likely(page_pool_unref_page(page, drain_count)))
 		return NULL;
 
-	if (page_ref_count(page) == 1 && !page_is_pfmemalloc(page)) {
+	if (__page_pool_page_can_be_recycled(page)) {
 		if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
 			page_pool_dma_sync_for_device(pool, page, -1);
 
-- 
2.44.0.278.ge034bb2e1d-goog

Re: [PATCH net-next v1] net: page_pool: factor out page_pool recycle check

[David Wei]

On 2024-03-08 12:44, Mina Almasry wrote:
> The check is duplicated in 2 places, factor it out into a common helper.
> 
> Signed-off-by: Mina Almasry <almasrymina@google.com>
> Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com>
> ---
>  net/core/page_pool.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index d706fe5548df..dd364d738c00 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -657,6 +657,11 @@ static bool page_pool_recycle_in_cache(struct page *page,
>  	return true;
>  }
>  
> +static bool __page_pool_page_can_be_recycled(const struct page *page)

Could this be made inline?

> +{
> +	return page_ref_count(page) == 1 && !page_is_pfmemalloc(page);
> +}
> +
>  /* If the page refcnt == 1, this will try to recycle the page.
>   * if PP_FLAG_DMA_SYNC_DEV is set, we'll try to sync the DMA area for
>   * the configured size min(dma_sync_size, pool->max_len).
> @@ -678,7 +683,7 @@ __page_pool_put_page(struct page_pool *pool, struct page *page,
>  	 * page is NOT reusable when allocated when system is under
>  	 * some pressure. (page_is_pfmemalloc)
>  	 */
> -	if (likely(page_ref_count(page) == 1 && !page_is_pfmemalloc(page))) {
> +	if (likely(__page_pool_page_can_be_recycled(page))) {
>  		/* Read barrier done in page_ref_count / READ_ONCE */
>  
>  		if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
> @@ -793,7 +798,7 @@ static struct page *page_pool_drain_frag(struct page_pool *pool,
>  	if (likely(page_pool_unref_page(page, drain_count)))
>  		return NULL;
>  
> -	if (page_ref_count(page) == 1 && !page_is_pfmemalloc(page)) {
> +	if (__page_pool_page_can_be_recycled(page)) {
>  		if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
>  			page_pool_dma_sync_for_device(pool, page, -1);
>  

Re: [PATCH net-next v1] net: page_pool: factor out page_pool recycle check

[Mina Almasry]

On Fri, Mar 8, 2024 at 3:50 PM David Wei <dw@davidwei.uk> wrote:
>
> On 2024-03-08 12:44, Mina Almasry wrote:
> > The check is duplicated in 2 places, factor it out into a common helper.
> >
> > Signed-off-by: Mina Almasry <almasrymina@google.com>
> > Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com>
> > ---
> >  net/core/page_pool.c | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> > index d706fe5548df..dd364d738c00 100644
> > --- a/net/core/page_pool.c
> > +++ b/net/core/page_pool.c
> > @@ -657,6 +657,11 @@ static bool page_pool_recycle_in_cache(struct page *page,
> >       return true;
> >  }
> >
> > +static bool __page_pool_page_can_be_recycled(const struct page *page)
>
> Could this be made inline?
>

Looking at the rest of the static functions in this file, they don't
specify inline, just static. I guess the compiler is smart enough to
inline static functions in .c files when it makes sense (and does not
when it doesn't)?

But this doesn't seem to be a kernel wide thing. net/core/dev.c does
have static inline functions in it, only page_pool.c doesn't do it. I
guess if there are no objections I can make it static inline to ask
the compiler to inline it. Likely after the merge window reopens if it
closes today.

Re: [PATCH net-next v1] net: page_pool: factor out page_pool recycle check

[David Wei]

On 2024-03-08 16:04, Mina Almasry wrote:
> On Fri, Mar 8, 2024 at 3:50 PM David Wei <dw@davidwei.uk> wrote:
>>
>> On 2024-03-08 12:44, Mina Almasry wrote:
>>> The check is duplicated in 2 places, factor it out into a common helper.
>>>
>>> Signed-off-by: Mina Almasry <almasrymina@google.com>
>>> Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com>
>>> ---
>>>  net/core/page_pool.c | 9 +++++++--
>>>  1 file changed, 7 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
>>> index d706fe5548df..dd364d738c00 100644
>>> --- a/net/core/page_pool.c
>>> +++ b/net/core/page_pool.c
>>> @@ -657,6 +657,11 @@ static bool page_pool_recycle_in_cache(struct page *page,
>>>       return true;
>>>  }
>>>
>>> +static bool __page_pool_page_can_be_recycled(const struct page *page)
>>
>> Could this be made inline?
>>
> 
> Looking at the rest of the static functions in this file, they don't
> specify inline, just static. I guess the compiler is smart enough to
> inline static functions in .c files when it makes sense (and does not
> when it doesn't)?
> 
> But this doesn't seem to be a kernel wide thing. net/core/dev.c does
> have static inline functions in it, only page_pool.c doesn't do it. I
> guess if there are no objections I can make it static inline to ask
> the compiler to inline it. Likely after the merge window reopens if it
> closes today.

Thanks for checking. Otherwise the change looks good to me, pulling out
the same check in two locations into a(n inline) function then calling
that function instead.

Re: [PATCH net-next v1] net: page_pool: factor out page_pool recycle check

[Jakub Kicinski]

On Fri, 8 Mar 2024 16:04:14 -0800 Mina Almasry wrote:
> > Could this be made inline?
> >  
> 
> Looking at the rest of the static functions in this file, they don't
> specify inline, just static. I guess the compiler is smart enough to
> inline static functions in .c files when it makes sense (and does not
> when it doesn't)?
> 
> But this doesn't seem to be a kernel wide thing. net/core/dev.c does
> have static inline functions in it, only page_pool.c doesn't do it. I
> guess if there are no objections I can make it static inline to ask
> the compiler to inline it. Likely after the merge window reopens if it
> closes today.

It's all good. We have a policy in netdev of "no inline unless you can
prove it makes a difference". It will not make a difference here and it
will mute the "unused function" warning.

Re: [PATCH net-next v1] net: page_pool: factor out page_pool recycle check

[Ilias Apalodimas]

On Fri, 8 Mar 2024 at 22:45, Mina Almasry <almasrymina@google.com> wrote:
>
> The check is duplicated in 2 places, factor it out into a common helper.
>
> Signed-off-by: Mina Almasry <almasrymina@google.com>
> Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com>
> ---
>  net/core/page_pool.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index d706fe5548df..dd364d738c00 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -657,6 +657,11 @@ static bool page_pool_recycle_in_cache(struct page *page,
>         return true;
>  }
>
> +static bool __page_pool_page_can_be_recycled(const struct page *page)
> +{
> +       return page_ref_count(page) == 1 && !page_is_pfmemalloc(page);
> +}
> +
>  /* If the page refcnt == 1, this will try to recycle the page.
>   * if PP_FLAG_DMA_SYNC_DEV is set, we'll try to sync the DMA area for
>   * the configured size min(dma_sync_size, pool->max_len).
> @@ -678,7 +683,7 @@ __page_pool_put_page(struct page_pool *pool, struct page *page,
>          * page is NOT reusable when allocated when system is under
>          * some pressure. (page_is_pfmemalloc)
>          */
> -       if (likely(page_ref_count(page) == 1 && !page_is_pfmemalloc(page))) {
> +       if (likely(__page_pool_page_can_be_recycled(page))) {
>                 /* Read barrier done in page_ref_count / READ_ONCE */
>
>                 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
> @@ -793,7 +798,7 @@ static struct page *page_pool_drain_frag(struct page_pool *pool,
>         if (likely(page_pool_unref_page(page, drain_count)))
>                 return NULL;
>
> -       if (page_ref_count(page) == 1 && !page_is_pfmemalloc(page)) {
> +       if (__page_pool_page_can_be_recycled(page)) {
>                 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
>                         page_pool_dma_sync_for_device(pool, page, -1);
>
> --
> 2.44.0.278.ge034bb2e1d-goog
>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

Re: [PATCH net-next v1] net: page_pool: factor out page_pool recycle check

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Fri,  8 Mar 2024 12:44:58 -0800 you wrote:
> The check is duplicated in 2 places, factor it out into a common helper.
> 
> Signed-off-by: Mina Almasry <almasrymina@google.com>
> Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com>
> ---
>  net/core/page_pool.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)

Here is the summary with links:
  - [net-next,v1] net: page_pool: factor out page_pool recycle check
    https://git.kernel.org/netdev/net-next/c/46f40172b681

You are awesome, thank you!
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