RE: [PATCH bpf-next 1/8] page_pool: Add callback to init pages when they are allocated

John Fastabend [off-list ref] writes:

Toke Høiland-Jørgensen wrote:

quoted

Add a new callback function to page_pool that, if set, will be called every
time a new page is allocated. This will be used from bpf_test_run() to
initialise the page data with the data provided by userspace when running
XDP programs with redirect turned on.

Signed-off-by: Toke Høiland-Jørgensen <redacted>
---

LGTM.

Acked-by: John Fastabend <john.fastabend@gmail.com>

quoted

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

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index 3855f069627f..a71201854c41 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h

@@ -80,6 +80,8 @@ struct page_pool_params {
 	enum dma_data_direction dma_dir; /* DMA mapping direction */
 	unsigned int	max_len; /* max DMA sync memory size */
 	unsigned int	offset;  /* DMA addr offset */
+	void (*init_callback)(struct page *page, void *arg);
+	void *init_arg;
 };
 
 struct page_pool {

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 9b60e4301a44..fb5a90b9d574 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c

@@ -219,6 +219,8 @@ static void page_pool_set_pp_info(struct page_pool *pool,
 {
 	page->pp = pool;
 	page->pp_magic |= PP_SIGNATURE;
+	if (unlikely(pool->p.init_callback))
+		pool->p.init_callback(page, pool->p.init_arg);

already in slow path right? So unlikely in a slow path should not
have any impact on performance is my reading.

Yeah, fair point, may have gone a little overboard on the "minimise
impact to existing code" here - will drop.

-Toke