From 31f084b7b0288fd51740b1e1efdb0ff61fb81e48 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Mon, 16 Jan 2023 16:48:59 +0000
Subject: [PATCH] io_uring: simplify fallback execution
Lock the ring with uring_lock in io_fallback_req_func(), which should
make it a bit safer and easier. With that we also don't need refs
pinning as io_ring_exit_work() will wait until uring_lock is freed.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/56170e6a0cbfc8edee2794c6613e8f6f1d76d276.1673887636.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
io_uring/io_uring.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index f49d0036657f3..c314dc111d5d6 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -245,17 +245,15 @@ static __cold void io_fallback_req_func(struct work_struct *work)
fallback_work.work);
struct llist_node *node = llist_del_all(&ctx->fallback_llist);
struct io_kiocb *req, *tmp;
- bool locked = false;
+ bool locked = true;
- percpu_ref_get(&ctx->refs);
+ mutex_lock(&ctx->uring_lock);
llist_for_each_entry_safe(req, tmp, node, io_task_work.node)
req->io_task_work.func(req, &locked);
-
- if (locked) {
- io_submit_flush_completions(ctx);
- mutex_unlock(&ctx->uring_lock);
- }
- percpu_ref_put(&ctx->refs);
+ if (WARN_ON_ONCE(!locked))
+ return;
+ io_submit_flush_completions(ctx);
+ mutex_unlock(&ctx->uring_lock);
}
static int io_alloc_hash_table(struct io_hash_table *table, unsigned bits)
--
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