linux-kernel - [PATCH] usb: gadget: f_serial: Ensure gserial disconnected during unbind

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Message-ID: <20220111064850.24311-1-quic_wcheng@quicinc.com>
Date:   Mon, 10 Jan 2022 22:48:50 -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_serial: Ensure gserial disconnected during unbind

Some UDCs may return an error during pullup disable as part of the
unbind path for a USB configuration.  This will lead to a scenario
where the disable() callback is skipped, whereas the unbind() still
occurs.  If this happens, the u_serial driver will continue to fail
subsequent binds, due to an already existing entry in the ports array.
Ensure that gserial_disconnect() is called during the f_serial unbind,
so the ports entry is properly cleared.

Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
---
 drivers/usb/gadget/function/f_serial.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/gadget/function/f_serial.c b/drivers/usb/gadget/function/f_serial.c
index 1ed8ff0ac2d3..a9480b9e312e 100644
--- a/drivers/usb/gadget/function/f_serial.c
+++ b/drivers/usb/gadget/function/f_serial.c
@@ -345,6 +345,10 @@ static void gser_free(struct usb_function *f)
 
 static void gser_unbind(struct usb_configuration *c, struct usb_function *f)
 {
+	struct f_gser	*gser = func_to_gser(f);
+
+	/* Ensure port is disconnected before unbinding */
+	gserial_disconnect(&gser->port);
 	usb_free_all_descriptors(f);
 }