linux-kernel - [PATCH] usb: gadget: f_fs: use io

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Message-Id: <20221124170430.3998755-1-john@metanate.com>
Date:   Thu, 24 Nov 2022 17:04:28 +0000
From:   John Keeping <john@...anate.com>
To:     linux-usb@...r.kernel.org
Cc:     John Keeping <john@...anate.com>,
        Linyu Yuan <quic_linyyuan@...cinc.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Dan Carpenter <error27@...il.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] usb: gadget: f_fs: use io_data->status consistently

Commit fb1f16d74e26 ("usb: gadget: f_fs: change ep->status safe in
ffs_epfile_io()") added a new ffs_io_data::status field to fix lifetime
issues in synchronous requests.

While there are no similar lifetime issues for asynchronous requests
(the separate ep member in ffs_io_data avoids them) using the status
field means the USB request can be freed earlier and that there is more
consistency between the synchronous and asynchronous I/O paths.

Cc: Linyu Yuan <quic_linyyuan@...cinc.com>
Signed-off-by: John Keeping <john@...anate.com>
---
 drivers/usb/gadget/function/f_fs.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 73dc10a77cde..1221f0d1b1a9 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -825,8 +825,7 @@ static void ffs_user_copy_worker(struct work_struct *work)
 {
 	struct ffs_io_data *io_data = container_of(work, struct ffs_io_data,
 						   work);
-	int ret = io_data->req->status ? io_data->req->status :
-					 io_data->req->actual;
+	int ret = io_data->status;
 	bool kiocb_has_eventfd = io_data->kiocb->ki_flags & IOCB_EVENTFD;
 
 	if (io_data->read && ret > 0) {
@@ -840,8 +839,6 @@ static void ffs_user_copy_worker(struct work_struct *work)
 	if (io_data->ffs->ffs_eventfd && !kiocb_has_eventfd)
 		eventfd_signal(io_data->ffs->ffs_eventfd, 1);
 
-	usb_ep_free_request(io_data->ep, io_data->req);
-
 	if (io_data->read)
 		kfree(io_data->to_free);
 	ffs_free_buffer(io_data);
@@ -856,6 +853,9 @@ static void ffs_epfile_async_io_complete(struct usb_ep *_ep,
 
 	ENTER();
 
+	io_data->status = req->status ? req->status : req->actual;
+	usb_ep_free_request(_ep, req);
+
 	INIT_WORK(&io_data->work, ffs_user_copy_worker);
 	queue_work(ffs->io_completion_wq, &io_data->work);
 }
-- 
2.38.1