io_uring: fix invalid flags for io_put_kbuf()

io_req_complete_failed() doesn't require callers to hold ->uring_lock,
use IO_URING_F_UNLOCKED version of io_put_kbuf(). The only affected
place is the fail path of io_apoll_task_func(). Also add a lockdep
annotation to catch such bugs in the future.

Fixes: 3b2b78a8eb7cc ("io_uring: extend provided buf return to fails")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ccf602dbf8df3b6a8552a262d8ee0a13a086fbc7.1648212967.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 0356b26..6143218 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1370,6 +1370,8 @@ static inline unsigned int io_put_kbuf(struct io_kiocb *req,
                cflags = __io_put_kbuf(req, &ctx->io_buffers_comp);
                spin_unlock(&ctx->completion_lock);
        } else {
+               lockdep_assert_held(&req->ctx->uring_lock);
+
                cflags = __io_put_kbuf(req, &req->ctx->io_buffers_cache);
        }
 
@@ -2165,7 +2167,7 @@ static inline void io_req_complete(struct io_kiocb *req, s32 res)
 static void io_req_complete_failed(struct io_kiocb *req, s32 res)
 {
        req_set_fail(req);
-       io_req_complete_post(req, res, io_put_kbuf(req, 0));
+       io_req_complete_post(req, res, io_put_kbuf(req, IO_URING_F_UNLOCKED));
 }
 
 static void io_req_complete_fail_submit(struct io_kiocb *req)