linux-kernel - [PATCH] io_uring/rsrc: Move lockdep assert from io_free_rsrc

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Message-Id: <20250120-uring-lockdep-assert-earlier-v1-1-68d8e071a4bb@google.com>
Date: Mon, 20 Jan 2025 17:21:57 +0100
From: Jann Horn <jannh@...gle.com>
To: Jens Axboe <axboe@...nel.dk>, Pavel Begunkov <asml.silence@...il.com>
Cc: io-uring@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Jann Horn <jannh@...gle.com>
Subject: [PATCH] io_uring/rsrc: Move lockdep assert from
 io_free_rsrc_node() to caller

Checking for lockdep_assert_held(&ctx->uring_lock) in io_free_rsrc_node()
means that the assertion is only checked when the resource drops to zero
references.
Move the lockdep assertion up into the caller io_put_rsrc_node() so that it
instead happens on every reference count decrement.

Signed-off-by: Jann Horn <jannh@...gle.com>
---
 io_uring/rsrc.c | 2 --
 io_uring/rsrc.h | 3 +++
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index a5fc035af8ff910d423930d7c662cc0e1a9f8444..af39b69eb4fde8b6e478e71c36dc04d3eec1b6d1 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -444,8 +444,6 @@ int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
 
 void io_free_rsrc_node(struct io_ring_ctx *ctx, struct io_rsrc_node *node)
 {
-	lockdep_assert_held(&ctx->uring_lock);
-
 	if (node->tag)
 		io_post_aux_cqe(ctx, node->tag, 0, 0);
 
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 5cd00b7baef8b03dd5f4a3aacee859b37db98e9b..190f7ee45de933b39a8c4d33dc86f687e338eb16 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -2,6 +2,8 @@
 #ifndef IOU_RSRC_H
 #define IOU_RSRC_H
 
+#include <linux/lockdep.h>
+
 #define IO_NODE_ALLOC_CACHE_MAX 32
 
 #define IO_RSRC_TAG_TABLE_SHIFT	(PAGE_SHIFT - 3)
@@ -80,6 +82,7 @@ static inline struct io_rsrc_node *io_rsrc_node_lookup(struct io_rsrc_data *data
 
 static inline void io_put_rsrc_node(struct io_ring_ctx *ctx, struct io_rsrc_node *node)
 {
+	lockdep_assert_held(&ctx->uring_lock);
 	if (node && !--node->refs)
 		io_free_rsrc_node(ctx, node);
 }

---
base-commit: e8153972dea537f1ae3ac45355fe3b2b3cbf59bf
change-id: 20250120-uring-lockdep-assert-earlier-264e039fafe5

-- 
Jann Horn <jannh@...gle.com>