From: Michael Kelley <mikelley@microsoft.com>
To: "Andrea Parri (Microsoft)" <parri.andrea@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Wei Liu <wei.liu@kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
Dexuan Cui <decui@microsoft.com>,
Boqun Feng <boqun.feng@gmail.com>, vkuznets <vkuznets@redhat.com>
Subject: RE: [PATCH 06/11] Drivers: hv: vmbus: Use a spin lock for synchronizing channel scheduling vs. channel removal
Date: Fri, 10 Apr 2020 19:28:44 +0000 [thread overview]
Message-ID: <DM5PR2101MB104791F7982BCD5FACD413EBD7DE0@DM5PR2101MB1047.namprd21.prod.outlook.com> (raw)
In-Reply-To: <20200406001514.19876-7-parri.andrea@gmail.com>
From: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Sent: Sunday, April 5, 2020 5:15 PM
>
> Since vmbus_chan_sched() dereferences the ring buffer pointer, we have
> to make sure that the ring buffer data structures don't get freed while
> such dereferencing is happening. Current code does this by sending an
> IPI to the CPU that is allowed to access that ring buffer from interrupt
> level, cf., vmbus_reset_channel_cb(). But with the new functionality
> to allow changing the CPU that a channel will interrupt, we can't be
> sure what CPU will be running the vmbus_chan_sched() function for a
> particular channel, so the current IPI mechanism is infeasible.
>
> Instead synchronize vmbus_chan_sched() and vmbus_reset_channel_cb() by
> using the (newly introduced) per-channel spin lock "sched_lock". Move
> the test for onchannel_callback being NULL before the "switch" control
> statement in vmbus_chan_sched(), in order to not access the ring buffer
> if the vmbus_reset_channel_cb() has been completed on the channel.
>
> Suggested-by: Michael Kelley <mikelley@microsoft.com>
> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
> ---
> drivers/hv/channel.c | 24 +++++++-----------------
> drivers/hv/channel_mgmt.c | 1 +
> drivers/hv/vmbus_drv.c | 30 +++++++++++++++++-------------
> include/linux/hyperv.h | 6 ++++++
> 4 files changed, 31 insertions(+), 30 deletions(-)
>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
next prev parent reply other threads:[~2020-04-10 19:28 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-06 0:15 [PATCH 00/11] VMBus channel interrupt reassignment Andrea Parri (Microsoft)
2020-04-06 0:15 ` [PATCH 01/11] Drivers: hv: vmbus: Always handle the VMBus messages on CPU0 Andrea Parri (Microsoft)
2020-04-10 17:18 ` Michael Kelley
2020-04-06 0:15 ` [PATCH 02/11] Drivers: hv: vmbus: Don't bind the offer&rescind works to a specific CPU Andrea Parri (Microsoft)
2020-04-10 17:23 ` Michael Kelley
2020-04-06 0:15 ` [PATCH 03/11] Drivers: hv: vmbus: Replace the per-CPU channel lists with a global array of channels Andrea Parri (Microsoft)
2020-04-10 17:29 ` Michael Kelley
2020-04-06 0:15 ` [PATCH 04/11] hv_netvsc: Disable NAPI before closing the VMBus channel Andrea Parri (Microsoft)
2020-04-10 19:20 ` Michael Kelley
2020-04-06 0:15 ` [PATCH 05/11] hv_utils: Always execute the fcopy and vss callbacks in a tasklet Andrea Parri (Microsoft)
2020-04-10 19:26 ` Michael Kelley
2020-04-06 0:15 ` [PATCH 06/11] Drivers: hv: vmbus: Use a spin lock for synchronizing channel scheduling vs. channel removal Andrea Parri (Microsoft)
2020-04-10 19:28 ` Michael Kelley [this message]
2020-04-06 0:15 ` [PATCH 07/11] PCI: hv: Prepare hv_compose_msi_msg() for the VMBus-channel-interrupt-to-vCPU reassignment functionality Andrea Parri (Microsoft)
2020-04-10 19:30 ` Michael Kelley
2020-04-06 0:15 ` [PATCH 08/11] Drivers: hv: vmbus: Remove the unused HV_LOCALIZED channel affinity logic Andrea Parri (Microsoft)
2020-04-10 19:32 ` Michael Kelley
2020-04-06 0:15 ` [PATCH 09/11] Drivers: hv: vmbus: Synchronize init_vp_index() vs. CPU hotplug Andrea Parri (Microsoft)
2020-04-10 19:33 ` Michael Kelley
2020-04-06 0:15 ` [PATCH 10/11] Drivers: hv: vmbus: Introduce the CHANNELMSG_MODIFYCHANNEL message type Andrea Parri (Microsoft)
2020-04-10 19:34 ` Michael Kelley
2020-04-06 0:15 ` [PATCH 11/11] scsi: storvsc: Re-init stor_chns when a channel interrupt is re-assigned Andrea Parri (Microsoft)
2020-04-06 19:54 ` Long Li
2020-04-07 0:35 ` Andrea Parri
2020-04-08 2:25 ` Long Li
2020-04-08 14:54 ` Andrea Parri
2020-04-10 19:35 ` Michael Kelley
2020-04-13 15:48 ` [PATCH 00/11] VMBus channel interrupt reassignment Wei Liu
2020-04-13 17:07 ` Andrea Parri
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