From 7c9e69428da39ed761c9d903c4850368fa4ef7bf Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Sat, 16 Nov 2019 12:22:43 +0100 Subject: [PATCH] page_pool: add destroy attempts counter and rename tracepoint MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When Jonathan change the page_pool to become responsible to its own shutdown via deferred work queue, then the disconnect_cnt counter was removed from xdp memory model tracepoint. This patch change the page_pool_inflight tracepoint name to page_pool_release, because it reflects the new responsability better. And it reintroduces a counter that reflect the number of times page_pool_release have been tried. The counter is also used by the code, to only empty the alloc cache once. With a stuck work queue running every second and counter being 64-bit, it will overrun in approx 584 billion years. For comparison, Earth lifetime expectancy is 7.5 billion years, before the Sun will engulf, and destroy, the Earth. Signed-off-by: Jesper Dangaard Brouer Acked-by: Toke Høiland-Jørgensen Signed-off-by: David S. Miller --- include/net/page_pool.h | 2 ++ include/trace/events/page_pool.h | 9 ++++++--- net/core/page_pool.c | 13 +++++++++++-- 3 files changed, 19 insertions(+), 5 deletions(-) diff --git a/include/net/page_pool.h b/include/net/page_pool.h index 1121faa99c12..ace881c15dcb 100644 --- a/include/net/page_pool.h +++ b/include/net/page_pool.h @@ -112,6 +112,8 @@ struct page_pool { * refcnt serves purpose is to simplify drivers error handling. */ refcount_t user_cnt; + + u64 destroy_cnt; }; struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp); diff --git a/include/trace/events/page_pool.h b/include/trace/events/page_pool.h index 47b5ee880aa9..ee7f1aca7839 100644 --- a/include/trace/events/page_pool.h +++ b/include/trace/events/page_pool.h @@ -10,7 +10,7 @@ #include -TRACE_EVENT(page_pool_inflight, +TRACE_EVENT(page_pool_release, TP_PROTO(const struct page_pool *pool, s32 inflight, u32 hold, u32 release), @@ -22,6 +22,7 @@ TRACE_EVENT(page_pool_inflight, __field(s32, inflight) __field(u32, hold) __field(u32, release) + __field(u64, cnt) ), TP_fast_assign( @@ -29,10 +30,12 @@ TRACE_EVENT(page_pool_inflight, __entry->inflight = inflight; __entry->hold = hold; __entry->release = release; + __entry->cnt = pool->destroy_cnt; ), - TP_printk("page_pool=%p inflight=%d hold=%u release=%u", - __entry->pool, __entry->inflight, __entry->hold, __entry->release) + TP_printk("page_pool=%p inflight=%d hold=%u release=%u cnt=%llu", + __entry->pool, __entry->inflight, __entry->hold, + __entry->release, __entry->cnt) ); TRACE_EVENT(page_pool_state_release, diff --git a/net/core/page_pool.c b/net/core/page_pool.c index dfc2501c35d9..e28db2ef8e12 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -200,7 +200,7 @@ static s32 page_pool_inflight(struct page_pool *pool) inflight = _distance(hold_cnt, release_cnt); - trace_page_pool_inflight(pool, inflight, hold_cnt, release_cnt); + trace_page_pool_release(pool, inflight, hold_cnt, release_cnt); WARN(inflight < 0, "Negative(%d) inflight packet-pages", inflight); return inflight; @@ -349,10 +349,13 @@ static void page_pool_free(struct page_pool *pool) kfree(pool); } -static void page_pool_scrub(struct page_pool *pool) +static void page_pool_empty_alloc_cache_once(struct page_pool *pool) { struct page *page; + if (pool->destroy_cnt) + return; + /* Empty alloc cache, assume caller made sure this is * no-longer in use, and page_pool_alloc_pages() cannot be * call concurrently. @@ -361,6 +364,12 @@ static void page_pool_scrub(struct page_pool *pool) page = pool->alloc.cache[--pool->alloc.count]; __page_pool_return_page(pool, page); } +} + +static void page_pool_scrub(struct page_pool *pool) +{ + page_pool_empty_alloc_cache_once(pool); + pool->destroy_cnt++; /* No more consumers should exist, but producers could still * be in-flight. -- 2.17.1