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@google.com>
Link: https://lore.kernel.org/r/20250120-uring-lockdep-assert-earlier-v1-1-68d8e071a4bb@google.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: thejh

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);
 

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);
 }