From: Andrea Parri <parri.andrea@gmail.com>
To: Michael Kelley <mikelley@microsoft.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Subject: Re: [PATCH v2 3/3] Drivers: hv: vmbus: Check for pending channel interrupts before taking a CPU offline
Date: Thu, 15 Apr 2021 13:39:18 +0200 [thread overview]
Message-ID: <20210415113918.GA75451@anparri> (raw)
In-Reply-To: <MWHPR21MB15931F523196BCE9E23293E4D74E9@MWHPR21MB1593.namprd21.prod.outlook.com>
> > @@ -336,6 +372,19 @@ int hv_synic_cleanup(unsigned int cpu)
> > if (channel_found && vmbus_connection.conn_state == CONNECTED)
> > return -EBUSY;
> >
> > + if (vmbus_proto_version >= VERSION_WIN10_V4_1) {
> > + /*
> > + * channel_found == false means that any channels that were previously
> > + * assigned to the CPU have been reassigned elsewhere with a call of
> > + * vmbus_send_modifychannel(). Scan the event flags page looking for
> > + * bits that are set and waiting with a timeout for vmbus_chan_sched()
> > + * to process such bits. If bits are still set after this operation
> > + * and VMBus is connected, fail the CPU offlining operation.
> > + */
> > + if (hv_synic_event_pending() && vmbus_connection.conn_state == CONNECTED)
> > + return -EBUSY;
> > + }
> > +
>
> Perhaps the test for conn_state == CONNECTED could be factored out as follows. If we're
> not CONNECTED (i.e., in the panic or kexec path) we should be able to also skip the search
> for channels that are bound to the CPU since we will ignore the result anyway.
>
> if (vmbus_connection.conn_state != CONNECTED)
> goto always_cleanup;
>
> if (cpu == VMBUS_CONNECT_CPU)
> return -EBUSY;
>
> [Code to search for channels that are bound to the CPU we're about to clean up]
>
> if (channel_found)
> return -EBUSY;
>
> /*
> * channel_found == false means that any channels that were previously
> * assigned to the CPU have been reassigned elsewhere with a call of
> * vmbus_send_modifychannel(). Scan the event flags page looking for
> * bits that are set and waiting with a timeout for vmbus_chan_sched()
> * to process such bits. If bits are still set after this operation
> * and VMBus is connected, fail the CPU offlining operation.
> */
> if (vmbus_proto_version >= VERSION_WIN10_V4_1 && hv_synic_event_pending())
> return -EBUSY;
>
> always_cleanup:
Agreed, applied. Thank you for the suggestion,
Andrea
prev parent reply other threads:[~2021-04-15 11:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-14 15:01 [PATCH v2 0/3] Drivers: hv: vmbus: Introduce CHANNELMSG_MODIFYCHANNEL_RESPONSE Andrea Parri (Microsoft)
2021-04-14 15:01 ` [PATCH v2 1/3] Drivers: hv: vmbus: Introduce and negotiate VMBus protocol version 5.3 Andrea Parri (Microsoft)
2021-04-14 18:25 ` Michael Kelley
2021-04-15 11:08 ` Andrea Parri
2021-04-14 15:01 ` [PATCH v2 2/3] Drivers: hv: vmbus: Drivers: hv: vmbus: Introduce CHANNELMSG_MODIFYCHANNEL_RESPONSE Andrea Parri (Microsoft)
2021-04-14 18:26 ` Michael Kelley
2021-04-14 15:01 ` [PATCH v2 3/3] Drivers: hv: vmbus: Check for pending channel interrupts before taking a CPU offline Andrea Parri (Microsoft)
2021-04-14 18:43 ` Michael Kelley
2021-04-15 11:39 ` Andrea Parri [this message]
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