Commit 1da4bbef authored by Ivan Khoronzhuk's avatar Ivan Khoronzhuk Committed by David S. Miller
Browse files

net: core: page_pool: add user refcnt and reintroduce page_pool_destroy 

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 reintroduce page_pool_destroy and add page_pool user
refcnt. This serves the purpose to 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.

This could be used for a 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 primarily to ease API usage for drivers. The recently
merged netsec driver, actually have a bug in this area, which is
solved by this API change.

This patch is a modified version of Ivan Khoronzhuk's original patch.

Link: https://lore.kernel.org/netdev/20190625175948.24771-2-ivan.khoronzhuk@linaro.org/


Fixes: 5c67bf0e ("net: netsec: Use page_pool API")
Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: default avatarIlias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: default avatarSaeed Mahameed <saeedm@mellanox.com>
Signed-off-by: default avatarIvan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 49db9228

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

+2 −2
Original line number Diff line number Diff line
@@ -577,8 +577,6 @@ 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;
@@ -646,6 +644,7 @@ err_rq_wq_destroy: 
	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;
@@ -680,6 +679,7 @@ 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);

}

drivers/net/ethernet/socionext/netsec.c

+2 −6
Original line number Diff line number Diff line
@@ -1212,15 +1212,11 @@ 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);

include/net/page_pool.h

+25 −0
Original line number Diff line number Diff line
@@ -101,6 +101,12 @@ 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 purpose is to simplify drivers error handling.

	 */

	refcount_t user_cnt;

};



struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
@@ -134,6 +140,15 @@ 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 +216,14 @@ 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 */

net/core/page_pool.c

+8 −0
Original line number Diff line number Diff line
@@ -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");

net/core/xdp.c

+3 −0
Original line number Diff line number Diff line
@@ -370,6 +370,9 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq, 
		goto err;

	}



	if (type == MEM_TYPE_PAGE_POOL)

		page_pool_get(xdp_alloc->page_pool);



	mutex_unlock(&mem_id_lock);



	trace_mem_connect(xdp_alloc, xdp_rxq);

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