From: Alan Stern <stern@rowland.harvard.edu>
To: naveen yadav <yad.naveen@gmail.com>
Cc: linux-kernel@vger.kernel.org, <majordomo@vger.kernel.org>,
<linux-usb@vger.kernel.org>, <marcel@holtmann.org>,
<padovan@profusion.mobi>
Subject: Re: USB 2.0: No giveback comes for one submitted URB
Date: Thu, 22 Nov 2012 10:38:17 -0500 (EST) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1211221036030.345-100000@netrider.rowland.org> (raw)
In-Reply-To: <CAJ8eaTwTM3b2wTa9=o3POy-dcP6hkE_DdoAVX06PBuPDhz4W6w@mail.gmail.com>
On Thu, 22 Nov 2012, naveen yadav wrote:
> Hi,
>
> we are using 3.2.2 version of kernel.
>
> When Bluetooth(connected to USB 2.0) is suspended, urb->use_count
> value does not become zero and eventually there is a continuous wait
> in wait_event() of usb_kill_urb().
> wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
>
> urb_count is incremented at only one place in usb_hcd_submit_urb() and
That's how it is _supposed_ to work. You have discovered that
something else increments urb->use_count.
> decremented in usb_hcd_giveback_urb(). (Also, in error case inside
> usb_hcd_submit_urb()). After taking print of urb->use_count at all
> these places, I see, even without connecting the Bluetooth device
> urb_count is incremented while below execution has never been
> decremented.
> .....
> [ 3.490000] ====>[usb_hcd_giveback_urb][1626] urb->use_count = 0
> pipe=2147484032 [vid=0x1d6b] [pid=0x0002][devno=1]
> [ 3.540000] ====>[usb_hcd_submit_urb][1482] urb->use_count = 2
> pipe=1077969280 [vid=0x1d6b] [pid=0x0002][devno=1]
> [ 3.540000] ====>[usb_hcd_giveback_urb][1626] urb->use_count = 1
> pipe=1077969280 [vid=0x1d6b] [pid=0x0002][devno=1]
Now you need to find out what other code has changed urb->use_count and
fix it.
Alan Stern
next prev parent reply other threads:[~2012-11-22 19:38 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CA+vmRF6jXXu+-ZMFgYNVJXV=kXUrezyYzpu5HOKPme95xQt0ug@mail.gmail.com>
[not found] ` <CA+vmRF6SCfvN2B6TnV1_XSoGmVG2WdRn2Cv-J-w+_tMd8hbeuw@mail.gmail.com>
2012-11-22 13:20 ` USB 2.0: No giveback comes for one submitted URB naveen yadav
2012-11-22 15:38 ` Alan Stern [this message]
2012-11-26 12:23 ` naveen yadav
2012-11-26 16:11 ` Alan Stern
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