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Date: Sat, 6 Mar 2010 19:48:19 +0100
From: Heinz Diehl <htd@fancy-poultry.org>
To: Oliver Neukum <oliver@neukum.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
       Petr Vandrovec <petr@vmware.com>, Jeff Chua <jeff.chua.linux@gmail.com>,
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       Linus Torvalds <torvalds@linux-foundation.org>,
       Linux Kernel <linux-kernel@vger.kernel.org>,
       Greg Kroah-Hartman <gregkh@suse.de>,
       Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: commit 554f76962d3a6eb5110415f1591aca83f96a84ae hangs USB for
 vmware 7.0.1
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On 06.03.2010, Oliver Neukum wrote:

> From: Oliver Neukum <oliver@neukum.org>
> Date: Sat, 6 Mar 2010 12:09:41 +0100
> Subject: [PATCH] usb: usbfs: Fix deadlock of khubd
>
> The caller of usbfs_conn_disc_event() already holds usbfs_mutex.
> Don't take it again.
>
> Signed-off-by: Oliver Neukum <neukum@b1-systems.de>
> ---
>  drivers/usb/core/devices.c |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/core/devices.c b/drivers/usb/core/devices.c
> index c83c975..08def6b 100644
> --- a/drivers/usb/core/devices.c
> +++ b/drivers/usb/core/devices.c
> @@ -155,11 +155,10 @@ static const struct class_info clas_info[] =
>
>  /*****************************************************************/
>
> +/* the caller holds usbfs_mutex */
>  void usbfs_conn_disc_event(void)
>  {
> -     mutex_lock(&usbfs_mutex);
>       conndiscevcnt++;
> -     mutex_unlock(&usbfs_mutex);
>       wake_up(&deviceconndiscwq);
>  }

I had a bug on my system which occured when I connected an USB mp3
player more than once:

When plugged in the first time, the device worked as expected. After
pulling it, it didn't get recognized again when plugged it.
Only a reboot did help.  2.6.33 final is fine, 2.6.33-gitX isn't.

Your patch, applied to -git11, did fix this.

Thanks,
Heinz.