Re: [PATCH] usb: gadget: f_fs: use io_data->status consistently

From: Linyu Yuan
Date: Thu Nov 24 2022 - 21:44:51 EST



Reviewed-by: Linyu Yuan <quic_linyyuan@xxxxxxxxxxx>


On 11/25/2022 1:04 AM, John Keeping wrote:
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@xxxxxxxxxxx>
Signed-off-by: John Keeping <john@xxxxxxxxxxxx>
---
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);
}