diff options
| -rw-r--r-- | drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 3 | ||||
| -rw-r--r-- | include/net/page_pool.h | 41 | ||||
| -rw-r--r-- | net/core/page_pool.c | 62 | ||||
| -rw-r--r-- | net/core/xdp.c | 65 |
4 files changed, 136 insertions, 35 deletions
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c index 46b6a47bd1e3..5e40db8f92e6 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c @@ -643,9 +643,6 @@ static void mlx5e_free_rq(struct mlx5e_rq *rq) } xdp_rxq_info_unreg(&rq->xdp_rxq); - if (rq->page_pool) - page_pool_destroy(rq->page_pool); - mlx5_wq_destroy(&rq->wq_ctrl); } diff --git a/include/net/page_pool.h b/include/net/page_pool.h index 754d980700df..f09b3f1994e6 100644 --- a/include/net/page_pool.h +++ b/include/net/page_pool.h @@ -16,14 +16,16 @@ * page_pool_alloc_pages() call. Drivers should likely use * page_pool_dev_alloc_pages() replacing dev_alloc_pages(). * - * If page_pool handles DMA mapping (use page->private), then API user - * is responsible for invoking page_pool_put_page() once. In-case of - * elevated refcnt, the DMA state is released, assuming other users of - * the page will eventually call put_page(). + * API keeps track of in-flight pages, in-order to let API user know + * when it is safe to dealloactor page_pool object. Thus, API users + * must make sure to call page_pool_release_page() when a page is + * "leaving" the page_pool. Or call page_pool_put_page() where + * appropiate. For maintaining correct accounting. * - * If no DMA mapping is done, then it can act as shim-layer that - * fall-through to alloc_page. As no state is kept on the page, the - * regular put_page() call is sufficient. + * API user must only call page_pool_put_page() once on a page, as it + * will either recycle the page, or in case of elevated refcnt, it + * will release the DMA mapping and in-flight state accounting. We + * hope to lift this requirement in the future. */ #ifndef _NET_PAGE_POOL_H #define _NET_PAGE_POOL_H @@ -66,9 +68,10 @@ struct page_pool_params { }; struct page_pool { - struct rcu_head rcu; struct page_pool_params p; + u32 pages_state_hold_cnt; + /* * Data structure for allocation side * @@ -96,6 +99,8 @@ struct page_pool { * TODO: Implement bulk return pages into this structure. */ struct ptr_ring ring; + + atomic_t pages_state_release_cnt; }; struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp); @@ -109,8 +114,6 @@ static inline struct page *page_pool_dev_alloc_pages(struct page_pool *pool) struct page_pool *page_pool_create(const struct page_pool_params *params); -void page_pool_destroy(struct page_pool *pool); - void __page_pool_free(struct page_pool *pool); static inline void page_pool_free(struct page_pool *pool) { @@ -143,6 +146,24 @@ static inline void page_pool_recycle_direct(struct page_pool *pool, __page_pool_put_page(pool, page, true); } +/* API user MUST have disconnected alloc-side (not allowed to call + * page_pool_alloc_pages()) before calling this. The free-side can + * still run concurrently, to handle in-flight packet-pages. + * + * A request to shutdown can fail (with false) if there are still + * in-flight packet-pages. + */ +bool __page_pool_request_shutdown(struct page_pool *pool); +static inline bool page_pool_request_shutdown(struct page_pool *pool) +{ + /* When page_pool isn't compiled-in, net/core/xdp.c doesn't + * allow registering MEM_TYPE_PAGE_POOL, but shield linker. + */ +#ifdef CONFIG_PAGE_POOL + return __page_pool_request_shutdown(pool); +#endif +} + /* Disconnects a page (from a page_pool). API users can have a need * to disconnect a page (from a page_pool), to allow it to be used as * a regular page (that will eventually be returned to the normal diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 41391b5dc14c..8679e24fd665 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -43,6 +43,8 @@ static int page_pool_init(struct page_pool *pool, if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0) return -ENOMEM; + atomic_set(&pool->pages_state_release_cnt, 0); + return 0; } @@ -151,6 +153,9 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool, page->dma_addr = dma; skip_dma_map: + /* Track how many pages are held 'in-flight' */ + pool->pages_state_hold_cnt++; + /* When page just alloc'ed is should/must have refcnt 1. */ return page; } @@ -173,6 +178,33 @@ struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp) } EXPORT_SYMBOL(page_pool_alloc_pages); +/* Calculate distance between two u32 values, valid if distance is below 2^(31) + * https://en.wikipedia.org/wiki/Serial_number_arithmetic#General_Solution + */ +#define _distance(a, b) (s32)((a) - (b)) + +static s32 page_pool_inflight(struct page_pool *pool) +{ + u32 release_cnt = atomic_read(&pool->pages_state_release_cnt); + u32 hold_cnt = READ_ONCE(pool->pages_state_hold_cnt); + s32 distance; + + distance = _distance(hold_cnt, release_cnt); + + /* TODO: Add tracepoint here */ + return distance; +} + +static bool __page_pool_safe_to_destroy(struct page_pool *pool) +{ + s32 inflight = page_pool_inflight(pool); + + /* The distance should not be able to become negative */ + WARN(inflight < 0, "Negative(%d) inflight packet-pages", inflight); + + return (inflight == 0); +} + /* Cleanup page_pool state from page */ static void __page_pool_clean_page(struct page_pool *pool, struct page *page) @@ -180,7 +212,7 @@ static void __page_pool_clean_page(struct page_pool *pool, dma_addr_t dma; if (!(pool->p.flags & PP_FLAG_DMA_MAP)) - return; + goto skip_dma_unmap; dma = page->dma_addr; /* DMA unmap */ @@ -188,11 +220,16 @@ static void __page_pool_clean_page(struct page_pool *pool, PAGE_SIZE << pool->p.order, pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC); page->dma_addr = 0; +skip_dma_unmap: + atomic_inc(&pool->pages_state_release_cnt); } /* unmap the page and clean our state */ void page_pool_unmap_page(struct page_pool *pool, struct page *page) { + /* When page is unmapped, this implies page will not be + * returned to page_pool. + */ __page_pool_clean_page(pool, page); } EXPORT_SYMBOL(page_pool_unmap_page); @@ -201,6 +238,7 @@ EXPORT_SYMBOL(page_pool_unmap_page); static void __page_pool_return_page(struct page_pool *pool, struct page *page) { __page_pool_clean_page(pool, page); + put_page(page); /* An optimization would be to call __free_pages(page, pool->p.order) * knowing page is not part of page-cache (thus avoiding a @@ -296,24 +334,17 @@ void __page_pool_free(struct page_pool *pool) { WARN(pool->alloc.count, "API usage violation"); WARN(!ptr_ring_empty(&pool->ring), "ptr_ring is not empty"); + WARN(!__page_pool_safe_to_destroy(pool), "still in-flight pages"); ptr_ring_cleanup(&pool->ring, NULL); kfree(pool); } EXPORT_SYMBOL(__page_pool_free); -static void __page_pool_destroy_rcu(struct rcu_head *rcu) -{ - struct page_pool *pool; - - pool = container_of(rcu, struct page_pool, rcu); - - __page_pool_empty_ring(pool); - __page_pool_free(pool); -} - -/* Cleanup and release resources */ -void page_pool_destroy(struct page_pool *pool) +/* Request to shutdown: release pages cached by page_pool, and check + * for in-flight pages + */ +bool __page_pool_request_shutdown(struct page_pool *pool) { struct page *page; @@ -331,7 +362,6 @@ void page_pool_destroy(struct page_pool *pool) */ __page_pool_empty_ring(pool); - /* An xdp_mem_allocator can still ref page_pool pointer */ - call_rcu(&pool->rcu, __page_pool_destroy_rcu); + return __page_pool_safe_to_destroy(pool); } -EXPORT_SYMBOL(page_pool_destroy); +EXPORT_SYMBOL(__page_pool_request_shutdown); diff --git a/net/core/xdp.c b/net/core/xdp.c index 0fcc32340c4e..aae665ccee3f 100644 --- a/net/core/xdp.c +++ b/net/core/xdp.c @@ -38,6 +38,7 @@ struct xdp_mem_allocator { }; struct rhash_head node; struct rcu_head rcu; + struct delayed_work defer_wq; }; static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed) @@ -79,13 +80,13 @@ static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu) xa = container_of(rcu, struct xdp_mem_allocator, rcu); + /* Allocator have indicated safe to remove before this is called */ + if (xa->mem.type == MEM_TYPE_PAGE_POOL) + page_pool_free(xa->page_pool); + /* Allow this ID to be reused */ ida_simple_remove(&mem_id_pool, xa->mem.id); - /* Notice, driver is expected to free the *allocator, - * e.g. page_pool, and MUST also use RCU free. - */ - /* Poison memory */ xa->mem.id = 0xFFFF; xa->mem.type = 0xF0F0; @@ -94,6 +95,46 @@ static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu) kfree(xa); } +bool __mem_id_disconnect(int id) +{ + struct xdp_mem_allocator *xa; + bool safe_to_remove = true; + + mutex_lock(&mem_id_lock); + + xa = rhashtable_lookup_fast(mem_id_ht, &id, mem_id_rht_params); + if (!xa) { + mutex_unlock(&mem_id_lock); + WARN(1, "Request remove non-existing id(%d), driver bug?", id); + return true; + } + + /* Detects in-flight packet-pages for page_pool */ + if (xa->mem.type == MEM_TYPE_PAGE_POOL) + safe_to_remove = page_pool_request_shutdown(xa->page_pool); + + if (safe_to_remove && + !rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params)) + call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free); + + mutex_unlock(&mem_id_lock); + return safe_to_remove; +} + +#define DEFER_TIME (msecs_to_jiffies(1000)) + +static void mem_id_disconnect_defer_retry(struct work_struct *wq) +{ + struct delayed_work *dwq = to_delayed_work(wq); + struct xdp_mem_allocator *xa = container_of(dwq, typeof(*xa), defer_wq); + + if (__mem_id_disconnect(xa->mem.id)) + return; + + /* Still not ready to be disconnected, retry later */ + schedule_delayed_work(&xa->defer_wq, DEFER_TIME); +} + void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq) { struct xdp_mem_allocator *xa; @@ -112,16 +153,28 @@ void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq) if (id == 0) return; + if (__mem_id_disconnect(id)) + return; + + /* Could not disconnect, defer new disconnect attempt to later */ mutex_lock(&mem_id_lock); xa = rhashtable_lookup_fast(mem_id_ht, &id, mem_id_rht_params); - if (xa && !rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params)) - call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free); + if (!xa) { + mutex_unlock(&mem_id_lock); + return; + } + INIT_DELAYED_WORK(&xa->defer_wq, mem_id_disconnect_defer_retry); mutex_unlock(&mem_id_lock); + schedule_delayed_work(&xa->defer_wq, DEFER_TIME); } EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg_mem_model); +/* This unregister operation will also cleanup and destroy the + * allocator. The page_pool_free() operation is first called when it's + * safe to remove, possibly deferred to a workqueue. + */ void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq) { /* Simplify driver cleanup code paths, allow unreg "unused" */ |