2023-02-03 01:16:27

by Qingfang Deng

Subject: [PATCH net-next v2] net: page_pool: use in_softirq() instead

From: Qingfang DENG <[email protected]>

We use BH context only for synchronization, so we don't care if it's
actually serving softirq or not.

As a side node, in case of threaded NAPI, in_serving_softirq() will
return false because it's in process context with BH off, making
page_pool_recycle_in_cache() unreachable.

Signed-off-by: Qingfang DENG <[email protected]>
---
v1 -> v2:
Drop the Fixes tags and repost against net-next.

include/net/page_pool.h | 4 ++--
net/core/page_pool.c | 6 +++---
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index 813c93499f20..34bf531ffc8d 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -386,7 +386,7 @@ static inline void page_pool_nid_changed(struct page_pool *pool, int new_nid)
static inline void page_pool_ring_lock(struct page_pool *pool)
__acquires(&pool->ring.producer_lock)
{
- if (in_serving_softirq())
+ if (in_softirq())
spin_lock(&pool->ring.producer_lock);
else
spin_lock_bh(&pool->ring.producer_lock);
@@ -395,7 +395,7 @@ static inline void page_pool_ring_lock(struct page_pool *pool)
static inline void page_pool_ring_unlock(struct page_pool *pool)
__releases(&pool->ring.producer_lock)
{
- if (in_serving_softirq())
+ if (in_softirq())
spin_unlock(&pool->ring.producer_lock);
else
spin_unlock_bh(&pool->ring.producer_lock);
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 9b203d8660e4..193c18799865 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -511,8 +511,8 @@ static void page_pool_return_page(struct page_pool *pool, struct page *page)
static bool page_pool_recycle_in_ring(struct page_pool *pool, struct page *page)
{
int ret;
- /* BH protection not needed if current is serving softirq */
- if (in_serving_softirq())
+ /* BH protection not needed if current is softirq */
+ if (in_softirq())
ret = ptr_ring_produce(&pool->ring, page);
else
ret = ptr_ring_produce_bh(&pool->ring, page);
@@ -570,7 +570,7 @@ __page_pool_put_page(struct page_pool *pool, struct page *page,
page_pool_dma_sync_for_device(pool, page,
dma_sync_size);

- if (allow_direct && in_serving_softirq() &&
+ if (allow_direct && in_softirq() &&
page_pool_recycle_in_cache(page, pool))
return NULL;

--
2.34.1

2023-02-03 13:36:52

by Felix Fietkau

Subject: Re: [PATCH net-next v2] net: page_pool: use in_softirq() instead

On 03.02.23 02:16, Qingfang DENG wrote:
> From: Qingfang DENG <[email protected]>
>
> We use BH context only for synchronization, so we don't care if it's
> actually serving softirq or not.
>
> As a side node, in case of threaded NAPI, in_serving_softirq() will
> return false because it's in process context with BH off, making
> page_pool_recycle_in_cache() unreachable.
>
> Signed-off-by: Qingfang DENG <[email protected]>
Tested-by: Felix Fietkau <[email protected]>

2023-02-06 09:20:25

by patchwork-bot+netdevbpf

Subject: Re: [PATCH net-next v2] net: page_pool: use in_softirq() instead

Hello:

This patch was applied to netdev/net-next.git (master)
by David S. Miller <[email protected]>:

On Fri, 3 Feb 2023 09:16:11 +0800 you wrote:
> From: Qingfang DENG <[email protected]>
>
> We use BH context only for synchronization, so we don't care if it's
> actually serving softirq or not.
>
> As a side node, in case of threaded NAPI, in_serving_softirq() will
> return false because it's in process context with BH off, making
> page_pool_recycle_in_cache() unreachable.
>
> [...]

Here is the summary with links:
- [net-next,v2] net: page_pool: use in_softirq() instead
https://git.kernel.org/netdev/net-next/c/542bcea4be86

You are awesome, thank you!
--
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