io_uring/napi: fix io_napi_entry RCU accesses

correct 3 RCU structures modifications that were not using the RCU
functions to make their update.

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>

diff --git a/io_uring/napi.c b/io_uring/napi.c
index dda2e083fb5da0c7409b6b1f44267a63e9c6212d..921de9de8d75397138f352e970b4023a38263030 100644 (file)
--- a/io_uring/napi.c
+++ b/io_uring/napi.c
@@ -81,19 +81,24 @@ void __io_napi_add(struct io_ring_ctx *ctx, struct socket *sock)
        }
 
        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) {
+       /*
+        * 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(&e->list);
+                       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 *ctx)
 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);
 }