From: Samiullah Khawaja <skhawaja@google.com>

Move the `dma_map` and `dma_sync` checks to `page_pool_init` to make
them generic. Set dma_sync to false for devmem memory provider because
the dma_sync APIs should not be used for dma_buf backed devmem memory
provider.

Cc: Jason Gunthorpe <jgg@ziepe.ca>
Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Mina Almasry <almasrymina@google.com>

---
 net/core/devmem.c    | 9 ++++-----
 net/core/page_pool.c | 3 +++
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/net/core/devmem.c b/net/core/devmem.c
index 11b91c12ee11..826d0b00159f 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -331,11 +331,10 @@ int mp_dmabuf_devmem_init(struct page_pool *pool)
 	if (!binding)
 		return -EINVAL;
 
-	if (!pool->dma_map)
-		return -EOPNOTSUPP;
-
-	if (pool->dma_sync)
-		return -EOPNOTSUPP;
+	/* dma-buf dma addresses should not be used with
+	 * dma_sync_for_cpu/device. Force disable dma_sync.
+	 */
+	pool->dma_sync = false;
 
 	if (pool->p.order != 0)
 		return -E2BIG;
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 3c0e19e13e64..060450082342 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -287,6 +287,9 @@ static int page_pool_init(struct page_pool *pool,
 	}
 
 	if (pool->mp_priv) {
+		if (!pool->dma_map || !pool->dma_sync)
+			return -EOPNOTSUPP;
+
 		err = mp_dmabuf_devmem_init(pool);
 		if (err) {
 			pr_warn("%s() mem-provider init failed %d\n", __func__,
-- 
2.47.0.338.g60cca15819-goog

On Mon,  9 Dec 2024 17:23:06 +0000 Mina Almasry wrote:
> +	/* dma-buf dma addresses should not be used with

Sounds a bit scary, maybe let's say:
                                 vvvvvvvvvvvvvvv
	/* dma-buf DMA addresses do not need and should not be used with

? up to you.