From: Pavel Begunkov <asml.silence@gmail.com>
Date: Thu, 30 Mar 2023 06:52:38 -0600
Subject: [PATCH] io_uring: fix poll/netmsg alloc caches
References: bsc#1012628
Patch-mainline: 6.2.10
Git-commit: fd30d1cdcc4ff405fc54765edf2e11b03f2ed4f3

commit fd30d1cdcc4ff405fc54765edf2e11b03f2ed4f3 upstream.

We increase cache->nr_cached when we free into the cache but don't
decrease when we take from it, so in some time we'll get an empty
cache with cache->nr_cached larger than IO_ALLOC_CACHE_MAX, that fails
io_alloc_cache_put() and effectively disables caching.

Fixes: 9b797a37c4bd8 ("io_uring: add abstraction around apoll cache")
Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 io_uring/alloc_cache.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/io_uring/alloc_cache.h b/io_uring/alloc_cache.h
index 729793ae..c2cde88a 100644
--- a/io_uring/alloc_cache.h
+++ b/io_uring/alloc_cache.h
@@ -27,6 +27,7 @@ static inline struct io_cache_entry *io_alloc_cache_get(struct io_alloc_cache *c
 		struct hlist_node *node = cache->list.first;
 
 		hlist_del(node);
+		cache->nr_cached--;
 		return container_of(node, struct io_cache_entry, node);
 	}
 
-- 
2.35.3