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

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

[Qingfang DENG]

From: Qingfang DENG <qingfang.deng@siflower.com.cn>

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 <qingfang.deng@siflower.com.cn>
---
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

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

[Felix Fietkau]

On 03.02.23 02:16, Qingfang DENG wrote:
> From: Qingfang DENG <qingfang.deng@siflower.com.cn>
> 
> 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 <qingfang.deng@siflower.com.cn>
Tested-by: Felix Fietkau <nbd@nbd.name>

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

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (master)
by David S. Miller <davem@davemloft.net>:

On Fri,  3 Feb 2023 09:16:11 +0800 you wrote:
> From: Qingfang DENG <qingfang.deng@siflower.com.cn>
> 
> 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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