Hi Jesper, > 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 use-case is > explicitly denied in this V2 patch, as it needs more discussion upstream. > > 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 Khoronzhu's original patch. > > Link: https://lore.kernel.org/netdev/20190625175948.24771-2-ivan.khoronzhuk@xxxxxxxxxx/ > Fixes: 5c67bf0ec4d0 ("net: netsec: Use page_pool API") > Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx> > --- > > I hope we can agree on this first step. Afterwards we can discuss, which is the > best approach for Ivan's two netdev's with one RX-queue API change. > > drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 6 ++--- > drivers/net/ethernet/socionext/netsec.c | 8 ++---- > include/net/page_pool.h | 26 +++++++++++++++++++++ > net/core/page_pool.c | 8 ++++++ > net/core/xdp.c | 9 +++++++ > 5 files changed, 48 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..0a0984d8f5d5 100644 > --- a/include/net/page_pool.h > +++ b/include/net/page_pool.h > @@ -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 +216,15 @@ static inline bool is_page_pool_compiled_in(void) > #endif > } > > +static inline unsigned int page_pool_get(struct page_pool *pool) > +{ > + refcount_inc(&pool->user_cnt); > + return refcount_read(&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..57c2317d9ce5 100644 > --- a/net/core/xdp.c > +++ b/net/core/xdp.c > @@ -370,6 +370,15 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq, > goto err; > } > > + if (type == MEM_TYPE_PAGE_POOL) { > + if (page_pool_get(xdp_alloc->page_pool) > 2) { > + WARN(1, "API misuse, argue to enable use-case"); > + page_pool_put(xdp_alloc->page_pool); > + errno = -EINVAL; > + goto err; > + } > + } > + > mutex_unlock(&mem_id_lock); > > trace_mem_connect(xdp_alloc, xdp_rxq); > For the netsec and page_pool part Reviewed-by: Ilias Apalodimas <ilias.apalodimas@xxxxxxxxxx>
