[net-next,2/3] page_pool: Turn dma_sync and dma_sync_cpu fields into a bitmap

Commit Message

Toke Høiland-Jørgensen March 14, 2025, 10:10 a.m. UTC

Change the single-bit booleans for dma_sync into an unsigned long with
BIT() definitions so that a subsequent patch can write them both with a
singe WRITE_ONCE() on teardown. Also move the check for the sync_cpu
side into __page_pool_dma_sync_for_cpu() so it can be disabled for
non-netmem providers as well.

Signed-off-by: Toke Høiland-Jørgensen <[e-mail]>
---
 include/net/page_pool/helpers.h | 6 +++---
 include/net/page_pool/types.h   | 8 ++++++--
 net/core/devmem.c               | 3 +--
 net/core/page_pool.c            | 9 +++++----
 4 files changed, 15 insertions(+), 11 deletions(-)

Patch

diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
index 582a3d00cbe2315edeb92850b6a42ab21e509e45..7ed32bde4b8944deb7fb22e291e95b8487be681a 100644
--- a/include/net/page_pool/helpers.h
+++ b/include/net/page_pool/helpers.h
@@ -443,6 +443,9 @@  static inline void __page_pool_dma_sync_for_cpu(const struct page_pool *pool,
 						const dma_addr_t dma_addr,
 						u32 offset, u32 dma_sync_size)
 {
+	if (!(READ_ONCE(pool->dma_sync) & PP_DMA_SYNC_CPU))
+		return;
+
 	dma_sync_single_range_for_cpu(pool->p.dev, dma_addr,
 				      offset + pool->p.offset, dma_sync_size,
 				      page_pool_get_dma_dir(pool));
@@ -473,9 +476,6 @@  page_pool_dma_sync_netmem_for_cpu(const struct page_pool *pool,
 				  const netmem_ref netmem, u32 offset,
 				  u32 dma_sync_size)
 {
-	if (!pool->dma_sync_for_cpu)
-		return;
-
 	__page_pool_dma_sync_for_cpu(pool,
 				     page_pool_get_dma_addr_netmem(netmem),
 				     offset, dma_sync_size);
diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index df0d3c1608929605224feb26173135ff37951ef8..fbe34024b20061e8bcd1d4474f6ebfc70992f1eb 100644
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -33,6 +33,10 @@ 
 #define PP_FLAG_ALL		(PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV | \
 				 PP_FLAG_SYSTEM_POOL | PP_FLAG_ALLOW_UNREADABLE_NETMEM)
 
+/* bit values used in pp->dma_sync */
+#define PP_DMA_SYNC_DEV	BIT(0)
+#define PP_DMA_SYNC_CPU	BIT(1)
+
 /*
  * Fast allocation side cache array/stack
  *
@@ -175,12 +179,12 @@  struct page_pool {
 
 	bool has_init_callback:1;	/* slow::init_callback is set */
 	bool dma_map:1;			/* Perform DMA mapping */
-	bool dma_sync:1;		/* Perform DMA sync for device */
-	bool dma_sync_for_cpu:1;	/* Perform DMA sync for cpu */
 #ifdef CONFIG_PAGE_POOL_STATS
 	bool system:1;			/* This is a global percpu pool */
 #endif
 
+	unsigned long dma_sync;
+
 	__cacheline_group_begin_aligned(frag, PAGE_POOL_FRAG_GROUP_ALIGN);
 	long frag_users;
 	netmem_ref frag_page;
diff --git a/net/core/devmem.c b/net/core/devmem.c
index 7c6e0b5b6acb55f376ec725dfb71d1f70a4320c3..16e43752566feb510b3e47fbec2d8da0f26a6adc 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -337,8 +337,7 @@  int mp_dmabuf_devmem_init(struct page_pool *pool)
 	/* dma-buf dma addresses do not need and should not be used with
 	 * dma_sync_for_cpu/device. Force disable dma_sync.
 	 */
-	pool->dma_sync = false;
-	pool->dma_sync_for_cpu = false;
+	pool->dma_sync = 0;
 
 	if (pool->p.order != 0)
 		return -E2BIG;
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index acef1fcd8ddcfd1853a6f2055c1f1820ab248e8d..d51ca4389dd62d8bc266a9a2b792838257173535 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -203,7 +203,7 @@  static int page_pool_init(struct page_pool *pool,
 	memcpy(&pool->slow, &params->slow, sizeof(pool->slow));
 
 	pool->cpuid = cpuid;
-	pool->dma_sync_for_cpu = true;
+	pool->dma_sync = PP_DMA_SYNC_CPU;
 
 	/* Validate only known flags were used */
 	if (pool->slow.flags & ~PP_FLAG_ALL)
@@ -238,7 +238,7 @@  static int page_pool_init(struct page_pool *pool,
 		if (!pool->p.max_len)
 			return -EINVAL;
 
-		pool->dma_sync = true;
+		pool->dma_sync |= PP_DMA_SYNC_DEV;
 
 		/* pool->p.offset has to be set according to the address
 		 * offset used by the DMA engine to start copying rx data
@@ -291,7 +291,7 @@  static int page_pool_init(struct page_pool *pool,
 	}
 
 	if (pool->mp_ops) {
-		if (!pool->dma_map || !pool->dma_sync)
+		if (!pool->dma_map || !(pool->dma_sync & PP_DMA_SYNC_DEV))
 			return -EOPNOTSUPP;
 
 		if (WARN_ON(!is_kernel_rodata((unsigned long)pool->mp_ops))) {
@@ -466,7 +466,8 @@  page_pool_dma_sync_for_device(const struct page_pool *pool,
 			      netmem_ref netmem,
 			      u32 dma_sync_size)
 {
-	if (pool->dma_sync && dma_dev_need_sync(pool->p.dev))
+	if ((READ_ONCE(pool->dma_sync) & PP_DMA_SYNC_DEV) &&
+	    dma_dev_need_sync(pool->p.dev))
 		__page_pool_dma_sync_for_device(pool, netmem, dma_sync_size);
 }