Re: [PATCH] Drivers: hv: vmbus: Add mutex lock to channel show functions

[Sasha Levin]

On Sat, Feb 02, 2019 at 03:07:35PM -0500, Kimberly Brown wrote:
> On Fri, Feb 01, 2019 at 06:24:24PM +0000, Dexuan Cui wrote:
> > > From: Kimberly Brown <kimbrownkd@xxxxxxxxx>
> > > Sent: Thursday, January 31, 2019 9:47 AM
> > > ...
> > > 2) Prevent a deadlock that can occur between the proposed mutex_lock()
> > > call in the vmbus_chan_attr_show() function and the sysfs/kernfs functions.
> > Hi Kim,
> > Can you please share more details about the deadlock?
> > It's unclear to me how the deadlock happens.
>
> Hi Dexuan,
>
> I encountered the deadlock by:
> 1) Adding a call to msleep() before acquiring the mutex in
> vmbus_chan_attr_show()
> 2) Opening a hv_netvsc subchannel's sysfs file
> 3) Removing hv_netvsc while the sysfs file is opening

Dexuan, any objections to pulling this fix in?

--
Thanks,
Sasha