[PATCH v2] io_uring/napi: clean up list traversal with list_for_each_entry_safe()

[Anvik Loitongbam]

Switch both loops to the standard list_for_each_entry_safe() pattern and
remove the explanatory comment.

Signed-off-by: Anvik Loitongbam <permissiontogallop@xxxxxxxxx>
---
v2:
  - Resend as a cleanup rather than a PREEMPT_RT UAF fix.

 io_uring/napi.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/io_uring/napi.c b/io_uring/napi.c
index 7e698720cd51..d299c89cfc3d 100644
--- a/io_uring/napi.c
+++ b/io_uring/napi.c
@@ -110,16 +110,10 @@ static int __io_napi_del_id(struct io_ring_ctx *ctx, unsigned int napi_id)
 
 static void __io_napi_remove_stale(struct io_ring_ctx *ctx)
 {
-	struct io_napi_entry *e;
+	struct io_napi_entry *e, *next;
 
 	guard(spinlock)(&ctx->napi_lock);
-	/*
-	 * 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) {
+	list_for_each_entry_safe(e, next, &ctx->napi_list, list) {
 		if (time_after(jiffies, READ_ONCE(e->timeout))) {
 			list_del_rcu(&e->list);
 			hash_del_rcu(&e->node);
@@ -264,10 +258,10 @@ void io_napi_init(struct io_ring_ctx *ctx)
  */
 void io_napi_free(struct io_ring_ctx *ctx)
 {
-	struct io_napi_entry *e;
+	struct io_napi_entry *e, *next;
 
 	guard(spinlock)(&ctx->napi_lock);
-	list_for_each_entry(e, &ctx->napi_list, list) {
+	list_for_each_entry_safe(e, next, &ctx->napi_list, list) {
 		hash_del_rcu(&e->node);
 		kfree_rcu(e, rcu);
 	}
--