diff options
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/page_pool.c | 62 | ||||
| -rw-r--r-- | net/core/xdp.c | 65 |
2 files changed, 105 insertions, 22 deletions
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" */ |