diff options
author | Jonathan Lemon <jonathan.lemon@gmail.com> | 2019-08-13 10:45:09 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2019-08-15 12:27:36 -0700 |
commit | 8d73f8f23e6b869b726cb01dd4747f56dc88660a (patch) | |
tree | a19e6d1e6829a6106b80e66a2440960cc2a164fa /net/core/page_pool.c | |
parent | 4b58c9b127f04bb3eea5a2a9ab8ef039b9fe9b71 (diff) | |
download | linux-8d73f8f23e6b869b726cb01dd4747f56dc88660a.tar.bz2 |
page_pool: fix logic in __page_pool_get_cached
__page_pool_get_cached() will return NULL when the ring is
empty, even if there are pages present in the lookaside cache.
It is also possible to refill the cache, and then return a
NULL page.
Restructure the logic so eliminate both cases.
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/page_pool.c')
-rw-r--r-- | net/core/page_pool.c | 39 |
1 files changed, 16 insertions, 23 deletions
diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 31187ff55cbc..5bc65587f1c4 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -82,12 +82,9 @@ EXPORT_SYMBOL(page_pool_create); static struct page *__page_pool_get_cached(struct page_pool *pool) { struct ptr_ring *r = &pool->ring; + bool refill = false; struct page *page; - /* Quicker fallback, avoid locks when ring is empty */ - if (__ptr_ring_empty(r)) - return NULL; - /* Test for safe-context, caller should provide this guarantee */ if (likely(in_serving_softirq())) { if (likely(pool->alloc.count)) { @@ -95,27 +92,23 @@ static struct page *__page_pool_get_cached(struct page_pool *pool) page = pool->alloc.cache[--pool->alloc.count]; return page; } - /* Slower-path: Alloc array empty, time to refill - * - * Open-coded bulk ptr_ring consumer. - * - * Discussion: the ring consumer lock is not really - * needed due to the softirq/NAPI protection, but - * later need the ability to reclaim pages on the - * ring. Thus, keeping the locks. - */ - spin_lock(&r->consumer_lock); - while ((page = __ptr_ring_consume(r))) { - if (pool->alloc.count == PP_ALLOC_CACHE_REFILL) - break; - pool->alloc.cache[pool->alloc.count++] = page; - } - spin_unlock(&r->consumer_lock); - return page; + refill = true; } - /* Slow-path: Get page from locked ring queue */ - page = ptr_ring_consume(&pool->ring); + /* Quicker fallback, avoid locks when ring is empty */ + if (__ptr_ring_empty(r)) + return NULL; + + /* Slow-path: Get page from locked ring queue, + * refill alloc array if requested. + */ + spin_lock(&r->consumer_lock); + page = __ptr_ring_consume(r); + if (refill) + pool->alloc.count = __ptr_ring_consume_batched(r, + pool->alloc.cache, + PP_ALLOC_CACHE_REFILL); + spin_unlock(&r->consumer_lock); return page; } |