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From: Alan Stern <stern@rowland.harvard.edu>
To: David Howells <dhowells@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>, <viro@zeniv.linux.org.uk>,
	Casey Schaufler <casey@schaufler-ca.com>,
	Stephen Smalley <sds@tycho.nsa.gov>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	<nicolas.dichtel@6wind.com>, <raven@themaw.net>,
	Christian Brauner <christian@brauner.io>,
	<keyrings@vger.kernel.org>, <linux-usb@vger.kernel.org>,
	<linux-security-module@vger.kernel.org>,
	<linux-fsdevel@vger.kernel.org>, <linux-api@vger.kernel.org>,
	<linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 08/11] usb: Add USB subsystem notifications [ver #7]
Date: Tue, 3 Sep 2019 13:17:07 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.4.44L0.1909031316130.1859-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1909031303500.1859-100000@iolanthe.rowland.org>

On Tue, 3 Sep 2019, Alan Stern wrote:

> On Tue, 3 Sep 2019, David Howells wrote:
> 
> > Guenter Roeck <linux@roeck-us.net> wrote:
> > 
> > > > > This added call to usbdev_remove() results in a crash when running
> > > > > the qemu "tosa" emulation. Removing the call fixes the problem.
> > > > 
> > > > Yeah - I'm going to drop the bus notification messages for now.
> > > > 
> > > It is not the bus notification itself causing problems. It is the
> > > call to usbdev_remove().
> > 
> > Unfortunately, I don't know how to fix it and don't have much time to
> > investigate it right now - and it's something that can be added back later.
> 
> The cause of your problem is quite simple:
> 
>  static int usbdev_notify(struct notifier_block *self,
>  			       unsigned long action, void *dev)
>  {
>  	switch (action) {
>  	case USB_DEVICE_ADD:
> +		post_usb_device_notification(dev, NOTIFY_USB_DEVICE_ADD, 0);
>  		break;
>  	case USB_DEVICE_REMOVE:
> +		post_usb_device_notification(dev, NOTIFY_USB_DEVICE_REMOVE, 0);
> +		usbdev_remove(dev);
> +		break;
> +	case USB_BUS_ADD:
> +		post_usb_bus_notification(dev, NOTIFY_USB_BUS_ADD, 0);
> +		break;
> +	case USB_BUS_REMOVE:
> +		post_usb_bus_notification(dev, NOTIFY_USB_BUS_REMOVE, 0);
>  		usbdev_remove(dev);
>  		break;
>  	}
> 
> The original code had usbdev_remove(dev) under the USB_DEVICE_REMOVE
> case.  The patch mistakenly moves it, putting it under the
------------------------------^^^^^

Sorry, I should have said "duplicates" it.

Alan Stern

> USB_BUS_REMOVE case.
> 
> If the usbdev_remove() call were left where it was originally, the 
> problem would be solved.
> 
> Alan Stern


  reply	other threads:[~2019-09-03 17:17 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190903085706.7700-1-hdanton@sina.com>
2019-08-30 13:57 ` [PATCH 00/11] Keyrings, Block and USB notifications [ver #7] David Howells
2019-08-30 13:57   ` [PATCH 01/11] uapi: General notification ring definitions " David Howells
2019-08-30 13:57   ` [PATCH 02/11] security: Add hooks to rule on setting a watch " David Howells
2019-08-30 13:57   ` [PATCH 03/11] security: Add a hook for the point of notification insertion " David Howells
2019-08-30 13:57   ` [PATCH 04/11] General notification queue with user mmap()'able ring buffer " David Howells
2019-08-30 13:57   ` [PATCH 05/11] keys: Add a notification facility " David Howells
2019-08-30 13:58   ` [PATCH 06/11] Add a general, global device notification watch list " David Howells
2019-09-03  8:34     ` Yoshihiro Shimoda
2019-09-03 16:41     ` David Howells
2019-08-30 13:58   ` [PATCH 07/11] block: Add block layer notifications " David Howells
2019-08-30 13:58   ` [PATCH 08/11] usb: Add USB subsystem " David Howells
2019-09-03  8:53     ` Yoshihiro Shimoda
2019-09-03  9:37       ` Greg Kroah-Hartman
2019-09-04  1:53         ` Yoshihiro Shimoda
2019-09-03 12:51     ` Guenter Roeck
2019-09-03 16:07     ` David Howells
2019-09-03 16:12       ` Guenter Roeck
2019-09-03 16:29       ` David Howells
2019-09-03 17:06         ` Alan Stern
2019-09-03 17:17           ` Alan Stern [this message]
2019-09-04 15:17             ` David Howells
2019-08-30 13:58   ` [PATCH 09/11] Add sample notification program " David Howells
2019-08-30 13:58   ` [PATCH 10/11] selinux: Implement the watch_key security hook " David Howells
2019-08-30 14:15     ` Stephen Smalley
2019-08-30 14:23     ` David Howells
2019-08-30 14:41     ` David Howells
2019-08-30 15:41       ` Stephen Smalley
2019-08-30 13:58   ` [PATCH 11/11] smack: Implement the watch_key and post_notification hooks [untested] " David Howells
2019-09-03 15:20     ` Casey Schaufler
2019-09-03 15:41     ` David Howells
2019-09-03 17:40       ` Casey Schaufler
2019-09-03 18:06       ` David Howells
2019-09-03 22:16         ` Casey Schaufler
2019-09-03 22:39         ` David Howells
2019-09-04 12:08         ` David Howells
2019-09-04 14:56           ` Casey Schaufler
2019-08-30 14:15   ` watch_queue(7) manpage David Howells
2019-08-30 14:15   ` watch_devices(2) manpage David Howells
2019-08-30 14:16   ` keyctl_watch_key.3 manpage David Howells
2019-08-30 22:09   ` [PATCH 00/11] Keyrings, Block and USB notifications [ver #7] Casey Schaufler
2019-09-02 12:39   ` David Howells
2019-09-02 13:26   ` David Howells
2019-09-03 16:06   ` [PATCH 04/11] General notification queue with user mmap()'able ring buffer " David Howells
2019-09-03 16:37   ` David Howells

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