[PATCH] net: core: page_pool: add user refcnt and reintroduce page_pool_destroy
From: Jesper Dangaard Brouer
Date: Tue Jul 02 2019 - 10:31:51 EST
From: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx>
Jesper recently removed page_pool_destroy() (from driver invocation) and
moved shutdown and free of page_pool into xdp_rxq_info_unreg(), in-order to
handle in-flight packets/pages. This created an asymmetry in drivers
create/destroy pairs.
This patch add page_pool user refcnt and reintroduce page_pool_destroy.
This serves two purposes, (1) simplify drivers error handling as driver now
drivers always calls page_pool_destroy() and don't need to track if
xdp_rxq_info_reg_mem_model() was unsuccessful. (2) allow special cases
where a single RX-queue (with a single page_pool) provides packets for two
net_device'es, and thus needs to register the same page_pool twice with two
xdp_rxq_info structures.
This patch is a modified version of Ivan Khoronzhuk's original patch.
Thus, Jesper gives author ownership to Ivan.
Link: https://lore.kernel.org/netdev/20190625175948.24771-2-ivan.khoronzhuk@xxxxxxxxxx/
Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
---
To Ivan,
If you agree with this patch, please add your Signed-off-by.
You can also say if you prefer to take this patch and make it
part of your driver patchset, what ever you prefer.
--Jesper
drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 6 ++---
drivers/net/ethernet/socionext/netsec.c | 8 ++----
include/net/page_pool.h | 27 +++++++++++++++++++++
net/core/page_pool.c | 8 ++++++
net/core/xdp.c | 3 ++
5 files changed, 43 insertions(+), 9 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 1085040675ae..ce1c7a449eae 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -545,10 +545,8 @@ static int mlx5e_alloc_rq(struct mlx5e_channel *c,
}
err = xdp_rxq_info_reg_mem_model(&rq->xdp_rxq,
MEM_TYPE_PAGE_POOL, rq->page_pool);
- if (err) {
- page_pool_free(rq->page_pool);
+ if (err)
goto err_free;
- }
for (i = 0; i < wq_sz; i++) {
if (rq->wq_type == MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ) {
@@ -613,6 +611,7 @@ static int mlx5e_alloc_rq(struct mlx5e_channel *c,
if (rq->xdp_prog)
bpf_prog_put(rq->xdp_prog);
xdp_rxq_info_unreg(&rq->xdp_rxq);
+ page_pool_destroy(rq->page_pool);
mlx5_wq_destroy(&rq->wq_ctrl);
return err;
@@ -643,6 +642,7 @@ static void mlx5e_free_rq(struct mlx5e_rq *rq)
}
xdp_rxq_info_unreg(&rq->xdp_rxq);
+ page_pool_destroy(rq->page_pool);
mlx5_wq_destroy(&rq->wq_ctrl);
}
diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c
index 5544a722543f..43ab0ce90704 100644
--- a/drivers/net/ethernet/socionext/netsec.c
+++ b/drivers/net/ethernet/socionext/netsec.c
@@ -1210,15 +1210,11 @@ static void netsec_uninit_pkt_dring(struct netsec_priv *priv, int id)
}
}
- /* Rx is currently using page_pool
- * since the pool is created during netsec_setup_rx_dring(), we need to
- * free the pool manually if the registration failed
- */
+ /* Rx is currently using page_pool */
if (id == NETSEC_RING_RX) {
if (xdp_rxq_info_is_reg(&dring->xdp_rxq))
xdp_rxq_info_unreg(&dring->xdp_rxq);
- else
- page_pool_free(dring->page_pool);
+ page_pool_destroy(dring->page_pool);
}
memset(dring->desc, 0, sizeof(struct netsec_desc) * DESC_NUM);
diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index ee9c871d2043..ea974856d0f7 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -101,6 +101,14 @@ struct page_pool {
struct ptr_ring ring;
atomic_t pages_state_release_cnt;
+
+ /* A page_pool is strictly tied to a single RX-queue being
+ * protected by NAPI, due to above pp_alloc_cache. This
+ * refcnt serves two purposes. (1) simplify drivers error
+ * handling, and (2) allow special cases where a single
+ * RX-queue provides packet for two net_device'es.
+ */
+ refcount_t user_cnt;
};
struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
@@ -134,6 +142,15 @@ static inline void page_pool_free(struct page_pool *pool)
#endif
}
+/* Drivers use this instead of page_pool_free */
+static inline void page_pool_destroy(struct page_pool *pool)
+{
+ if (!pool)
+ return;
+
+ page_pool_free(pool);
+}
+
/* Never call this directly, use helpers below */
void __page_pool_put_page(struct page_pool *pool,
struct page *page, bool allow_direct);
@@ -201,4 +218,14 @@ static inline bool is_page_pool_compiled_in(void)
#endif
}
+static inline void page_pool_get(struct page_pool *pool)
+{
+ refcount_inc(&pool->user_cnt);
+}
+
+static inline bool page_pool_put(struct page_pool *pool)
+{
+ return refcount_dec_and_test(&pool->user_cnt);
+}
+
#endif /* _NET_PAGE_POOL_H */
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index b366f59885c1..3272dc7a8c81 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -49,6 +49,9 @@ static int page_pool_init(struct page_pool *pool,
atomic_set(&pool->pages_state_release_cnt, 0);
+ /* Driver calling page_pool_create() also call page_pool_destroy() */
+ refcount_set(&pool->user_cnt, 1);
+
if (pool->p.flags & PP_FLAG_DMA_MAP)
get_device(pool->p.dev);
@@ -70,6 +73,7 @@ struct page_pool *page_pool_create(const struct page_pool_params *params)
kfree(pool);
return ERR_PTR(err);
}
+
return pool;
}
EXPORT_SYMBOL(page_pool_create);
@@ -356,6 +360,10 @@ static void __warn_in_flight(struct page_pool *pool)
void __page_pool_free(struct page_pool *pool)
{
+ /* Only last user actually free/release resources */
+ if (!page_pool_put(pool))
+ return;
+
WARN(pool->alloc.count, "API usage violation");
WARN(!ptr_ring_empty(&pool->ring), "ptr_ring is not empty");
diff --git a/net/core/xdp.c b/net/core/xdp.c
index b29d7b513a18..e57a0eb1feb7 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -372,6 +372,9 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
mutex_unlock(&mem_id_lock);
+ if (type == MEM_TYPE_PAGE_POOL)
+ page_pool_get(xdp_alloc->page_pool);
+
trace_mem_connect(xdp_alloc, xdp_rxq);
return 0;
err: