From: Alan Stern <stern@rowland.harvard.edu>
To: Shuah Khan <skhan@linuxfoundation.org>
Cc: Andrey Konovalov <andreyknvl@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Valentina Manea <valentina.manea.m@gmail.com>,
Shuah Khan <shuah@kernel.org>,
USB list <linux-usb@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Dmitry Vyukov <dvyukov@google.com>,
Nazime Hande Harputluoglu <handeharputlu@google.com>,
syzkaller <syzkaller@googlegroups.com>
Subject: Re: Is usb_hcd_giveback_urb() allowed in task context?
Date: Mon, 5 Oct 2020 21:23:33 -0400 [thread overview]
Message-ID: <20201006012333.GA399825@rowland.harvard.edu> (raw)
In-Reply-To: <65b4ff62-f9c8-b9cf-50bb-c9b08cce7230@linuxfoundation.org>
On Mon, Oct 05, 2020 at 05:38:22PM -0600, Shuah Khan wrote:
> On 10/5/20 9:25 AM, Alan Stern wrote:
> > On Mon, Oct 05, 2020 at 05:21:30PM +0200, Andrey Konovalov wrote:
> > No, no -- it won't work right if it's called in process context. Not
> > only do the spinlock calls leave the interrupt flag unchanged, also the
> > driver callback routines may expect to be invoked with interrupts
> > disabled. (We have tried to fix this, but I'm not at all certain that
> > all the cases have been updated.)
> >
>
> In the case of vhci case, usb_hcd_giveback_urb() is called from vhci's
> urb_enqueue, when it determines it doesn't need to xmit the urb and can give
> it back. This path runs in task context.
>
> Do you have any recommendation on how this case can be handled?
Just call local_irq_disable() before usb_hcd_giveback_urb(), and
local_irq_enable() afterward.
Alan Stern
next prev parent reply other threads:[~2020-10-06 1:23 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-05 15:08 Andrey Konovalov
2020-10-05 15:18 ` Greg Kroah-Hartman
2020-10-05 15:21 ` Andrey Konovalov
2020-10-05 15:25 ` Alan Stern
2020-10-05 23:38 ` Shuah Khan
2020-10-06 1:23 ` Alan Stern [this message]
2020-10-06 15:44 ` Andrey Konovalov
2020-10-05 15:22 ` Alan Stern
2020-10-05 15:28 ` Greg Kroah-Hartman
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