linux-kernel - [PATCH] usb: gadget: f_fs: Wake up IO thread during disconnect

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Date:   Wed, 1 Dec 2021 02:02:05 -0800
From:   Wesley Cheng <quic_wcheng@...cinc.com>
To:     <balbi@...nel.org>, <gregkh@...uxfoundation.org>
CC:     <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <quic_jackp@...cinc.com>, Wesley Cheng <quic_wcheng@...cinc.com>
Subject: [PATCH] usb: gadget: f_fs: Wake up IO thread during disconnect

During device disconnect or composition unbind, applications should be
notified that the endpoints are no longer enabled, so that it can take
the proper actions to handle its IO threads.  Otherwise, they can be
left waiting for endpoints until EPs are re-enabled.

Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
---
 drivers/usb/gadget/function/f_fs.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 3c584da9118c..0b0747d96378 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -957,10 +957,12 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 		if (file->f_flags & O_NONBLOCK)
 			return -EAGAIN;
 
-		ret = wait_event_interruptible(
-				epfile->ffs->wait, (ep = epfile->ep));
+		ret = wait_event_interruptible(epfile->ffs->wait,
+				(ep = epfile->ep) || !epfile->ffs->func);
 		if (ret)
 			return -EINTR;
+		if (!epfile->ffs->func)
+			return -ENODEV;
 	}
 
 	/* Do we halt? */
@@ -3292,6 +3294,7 @@ static int ffs_func_set_alt(struct usb_function *f,
 	if (alt == (unsigned)-1) {
 		ffs->func = NULL;
 		ffs_event_add(ffs, FUNCTIONFS_DISABLE);
+		wake_up_interruptible(&ffs->wait);
 		return 0;
 	}