I managed to get a device vt6656 (USB WiFi adapter). The device works OK
when the computer is started and driver loaded. When the WLAN is
disabled the system freezes often.
I am using ubuntu 20.04 with kernel 5.17.0-rc1 x86_64
branch: staging-testing
After some tries I found out that it is a function in vnt_stop()
main_usb.c with the following line that is causing this.
usb_kill_urb(priv→interrupt_urb);
But this memory is after this line still in use.
Digging deeper I found that the usb_submit_urb() function (in usbpipe.c
vnt_start_interrupt_urb_complete) is called after the usb_kill_urb() is
executed.
So I tied the execution of the usb_submit_urb() to a flag called
DEVICE_FLAGS_DISCONNECTED. After that no crashes were observed.
So here my questions:
- Is this the right place to fix?
- Do I need to log a bug report before a patch?
Here a patch proposal:
From d403ed1a1c2483a3a8b44e96c12edbfa2a53d356 Mon Sep 17 00:00:00 2001
From: Philipp Hortmann <philipp.g.hortmann@xxxxxxxxx>
Date: Wed, 2 Feb 2022 20:15:04 +0100
Subject: [PATCH] staging: vt6656: Fix crash when WLAN is turned off
To: Forest Bond <forest@xxxxxxxxxxxxxxxxxxx>,Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx>,linux-staging@xxxxxxxxxxxxxxx,linux-kernel@xxxxxxxxxxxxxxx
Stop submitting urbs before calling usb_kill_urb() and usb_free_urb().
Signed-off-by: Philipp Hortmann <philipp.g.hortmann@xxxxxxxxx>
---
drivers/staging/vt6656/usbpipe.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/staging/vt6656/usbpipe.c
b/drivers/staging/vt6656/usbpipe.c
index 7f45734390f6..d505b4b69ba4 100644
--- a/drivers/staging/vt6656/usbpipe.c
+++ b/drivers/staging/vt6656/usbpipe.c
@@ -230,7 +230,9 @@ static void vnt_start_interrupt_urb_complete(struct
urb *urb)
else
vnt_int_process_data(priv);
- status = usb_submit_urb(priv->interrupt_urb, GFP_ATOMIC);
+ if (!test_bit(DEVICE_FLAGS_DISCONNECTED, &priv->flags))
+ status = usb_submit_urb(priv->interrupt_urb, GFP_ATOMIC);
+
if (status)
dev_dbg(&priv->usb->dev, "Submit int URB failed %d\n", status);
}
--
2.25.1
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