[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date: Sat, 12 Dec 2015 00:49:54 +0000
From: KY Srinivasan <kys@...rosoft.com>
To: Dexuan Cui <decui@...rosoft.com>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
"olaf@...fle.de" <olaf@...fle.de>,
"apw@...onical.com" <apw@...onical.com>,
"vkuznets@...hat.com" <vkuznets@...hat.com>,
"jasowang@...hat.com" <jasowang@...hat.com>
Subject: RE: [PATCH V2 02/10] Drivers: hv: utils: run polling callback always
in interrupt context
> -----Original Message-----
> From: Dexuan Cui
> Sent: Thursday, December 10, 2015 11:33 PM
> To: KY Srinivasan <kys@...rosoft.com>; gregkh@...uxfoundation.org; linux-
> kernel@...r.kernel.org; devel@...uxdriverproject.org; olaf@...fle.de;
> apw@...onical.com; vkuznets@...hat.com; jasowang@...hat.com
> Subject: RE: [PATCH V2 02/10] Drivers: hv: utils: run polling callback always in
> interrupt context
>
> > -----Original Message-----
> > From: KY Srinivasan
> > Sent: Friday, December 11, 2015 7:23
> > > It looks the patch has not been Greg's tree yet.
> > >
> > > I have 2 questions about the patch:
> > >
> > > 1. hv_poll_channel() is invoked in fcopy_handle_handshake(), but not in
> > > vss_handle_handshake() and kvp_handle_handshake().
> > > Why -- I guess we missed the vss/kvp cases somehow?
> > I will fix this.
>
> Thanks, KY!
> BTW, I fixed another small issue by https://lkml.org/lkml/2015/12/10/50
> (The mail is attached for your convenience)
I will pick this up.
>
> > > 2. With the patch, hv_fcopy_onchannelcallback() can be invoked in the
> > > tasklet (i.e., vmbus_on_event(). NB: local irq is enabled), and in the
> > > hard irq handler(the IPI handler, e.g.,
> > > fcopy_poll_wrapper() -> fcopy_poll_wrapper()).
> > >
> > > Can the former be interrupted by the latter?
> > > e.g., when the callback is running in the tasklet on vCPU0,
> > > fcopy_timeout_func() or fcopy_on_msg() could send the IPI to
> > > vCPU0 from another vCPU.
> >
> > Keep in mind that when the poll function is run, the state will not be
> > HVUTIL_READY. The state will be set to HVUTIL_READY in the IPI
> > handler. So, it is ok if the tasklet is interrupted by the IPI handler.
> >
> > K. Y
>
> Got it.
>
> BTW, in fcopy_handle_handshake(), IMO the line
> fcopy_transaction.state = HVUTIL_READY;
> just before
> hv_poll_channel(fcopy_transaction.recv_channel, fcopy_poll_wrapper);
> should be removed? Because in fcopy_poll_wrapper() we always have
> the same line.
>
> Ditto for kvp/vss.
>
> Thanks,
I will fix this and resend.
Thanks,
K. Y
> -- Dexuan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists