RE: [PATCH V2 1/4] vmbus: don't acquire the mutex in vmbus_hvsock_device_unregister()

From: KY Srinivasan
Date: Mon Sep 18 2017 - 10:43:59 EST




> -----Original Message-----
> From: Greg KH [mailto:gregkh@xxxxxxxxxxxxxxxxxxx]
> Sent: Monday, September 18, 2017 7:00 AM
> To: KY Srinivasan <kys@xxxxxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx;
> olaf@xxxxxxxxx; apw@xxxxxxxxxxxxx; vkuznets@xxxxxxxxxx;
> jasowang@xxxxxxxxxx; leann.ogasawara@xxxxxxxxxxxxx;
> marcelo.cerri@xxxxxxxxxxxxx; Stephen Hemminger
> <sthemmin@xxxxxxxxxxxxx>; Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> Subject: Re: [PATCH V2 1/4] vmbus: don't acquire the mutex in
> vmbus_hvsock_device_unregister()
>
> On Sun, Sep 17, 2017 at 08:54:16PM -0700, kys@xxxxxxxxxxxxxxxxxxxxxx
> wrote:
> > From: Dexuan Cui <decui@xxxxxxxxxxxxx>
> >
> > Due to commit 54a66265d675 ("Drivers: hv: vmbus: Fix rescind handling"),
> > we need this patch to resolve the below deadlock:
> >
> > after we get the mutex in vmbus_hvsock_device_unregister() and call
> > vmbus_device_unregister() -> device_unregister() -> ... ->
> device_release()
> > -> vmbus_device_release(), we'll get a deadlock, because
> > vmbus_device_release() tries to get the same mutex.
> >
> > Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> > Cc: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> > Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> > Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
> > Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
>
> As every one of these patches had questions from me, please break them
> up into different series, one for 4.14-final, and one for 4.15-rc1.

Will do.

Thanks,

K. Y
>
> thanks,
>
> greg k-h