* [PATCH 6.12 172/185] io_uring/napi: fix io_napi_entry RCU accesses
[not found] <20251121130143.857798067@linuxfoundation.org>
@ 2025-11-21 13:13 ` Greg Kroah-Hartman
0 siblings, 0 replies; only message in thread
From: Greg Kroah-Hartman @ 2025-11-21 13:13 UTC (permalink / raw)
To: stable
Cc: Greg Kroah-Hartman, patches, Jens Axboe, Pavel Begunkov, io-uring,
linux-kernel, lvc-project, Olivier Langlois, Stepan Artuhov
6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Olivier Langlois <olivier@trillion01.com>
[Upstream commit 45b3941d09d13b3503309be1f023b83deaf69b4d ]
correct 3 RCU structures modifications that were not using the RCU
functions to make their update.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: io-uring@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: lvc-project@linuxtesting.org
Signed-off-by: Olivier Langlois <olivier@trillion01.com>
Link: https://lore.kernel.org/r/9f53b5169afa8c7bf3665a0b19dc2f7061173530.1728828877.git.olivier@trillion01.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[Stepan Artuhov: cherry-picked a commit]
Signed-off-by: Stepan Artuhov <s.artuhov@tssltd.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
io_uring/napi.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
--- a/io_uring/napi.c
+++ b/io_uring/napi.c
@@ -81,19 +81,24 @@ void __io_napi_add(struct io_ring_ctx *c
}
hlist_add_tail_rcu(&e->node, hash_list);
- list_add_tail(&e->list, &ctx->napi_list);
+ list_add_tail_rcu(&e->list, &ctx->napi_list);
spin_unlock(&ctx->napi_lock);
}
static void __io_napi_remove_stale(struct io_ring_ctx *ctx)
{
struct io_napi_entry *e;
- unsigned int i;
spin_lock(&ctx->napi_lock);
- hash_for_each(ctx->napi_ht, i, e, node) {
- if (time_after(jiffies, e->timeout)) {
- list_del(&e->list);
+ /*
+ * list_for_each_entry_safe() is not required as long as:
+ * 1. list_del_rcu() does not reset the deleted node next pointer
+ * 2. kfree_rcu() delays the memory freeing until the next quiescent
+ * state
+ */
+ list_for_each_entry(e, &ctx->napi_list, list) {
+ if (time_after(jiffies, READ_ONCE(e->timeout))) {
+ list_del_rcu(&e->list);
hash_del_rcu(&e->node);
kfree_rcu(e, rcu);
}
@@ -204,13 +209,13 @@ void io_napi_init(struct io_ring_ctx *ct
void io_napi_free(struct io_ring_ctx *ctx)
{
struct io_napi_entry *e;
- unsigned int i;
spin_lock(&ctx->napi_lock);
- hash_for_each(ctx->napi_ht, i, e, node) {
+ list_for_each_entry(e, &ctx->napi_list, list) {
hash_del_rcu(&e->node);
kfree_rcu(e, rcu);
}
+ INIT_LIST_HEAD_RCU(&ctx->napi_list);
spin_unlock(&ctx->napi_lock);
}
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