linux-kernel - [PATCH v2 2/2] usb: gadget: f_mass_storage: Disable eps during disconnect

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Date:   Tue, 26 Oct 2021 19:50:25 -0700
From:   Wesley Cheng <quic_wcheng@...cinc.com>
To:     <balbi@...nel.org>, <gregkh@...uxfoundation.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <jackp@...eaurora.org>, Wesley Cheng <quic_wcheng@...cinc.com>
Subject: [PATCH v2 2/2] usb: gadget: f_mass_storage: Disable eps during disconnect

When receiving a disconnect event from the UDC, the mass storage
function driver currently runs the handle_exception() routine
asynchronously.  For UDCs that support runtime PM, there is a
possibility the UDC is already suspended by the time the
do_set_interface() is executed.  This can lead to HW register access
while the UDC is already suspended.

Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
---
 drivers/usb/gadget/function/f_mass_storage.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/usb/gadget/function/f_mass_storage.c b/drivers/usb/gadget/function/f_mass_storage.c
index 3cabf76..7524396 100644
--- a/drivers/usb/gadget/function/f_mass_storage.c
+++ b/drivers/usb/gadget/function/f_mass_storage.c
@@ -2342,6 +2342,16 @@ static void fsg_disable(struct usb_function *f)
 {
 	struct fsg_dev *fsg = fsg_from_func(f);
 
+	/* Disable the endpoints */
+	if (fsg->bulk_in_enabled) {
+		usb_ep_disable(fsg->bulk_in);
+		fsg->bulk_in_enabled = 0;
+	}
+	if (fsg->bulk_out_enabled) {
+		usb_ep_disable(fsg->bulk_out);
+		fsg->bulk_out_enabled = 0;
+	}
+
 	__raise_exception(fsg->common, FSG_STATE_CONFIG_CHANGE, NULL);
 }