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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 09/11] Drivers: hv: vmbus: Synchronize init_vp_index() vs.
 CPU hotplug
Thread-Topic: [PATCH 09/11] Drivers: hv: vmbus: Synchronize init_vp_index()
 vs. CPU hotplug
Thread-Index: AQHWC6izYGPdkF4IY0O6b+yNKo8O5qhyxkVA
Date:   Fri, 10 Apr 2020 19:33:47 +0000
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References: <20200406001514.19876-1-parri.andrea@gmail.com>
 <20200406001514.19876-10-parri.andrea@gmail.com>
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From: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Sent: Sunday, April=
 5, 2020 5:15 PM
>=20
> init_vp_index() may access the cpu_online_mask mask via its calls of
> cpumask_of_node().  Make sure to protect these accesses with a
> cpus_read_lock() critical section.
>=20
> Also, remove some (hardcoded) instances of CPU(0) from init_vp_index()
> and replace them with VMBUS_CONNECT_CPU.  The connect CPU can not go
> offline, since Hyper-V does not provide a way to change it.
>=20
> Finally, order the accesses of target_cpu from init_vp_index() and
> hv_synic_cleanup() by relying on the channel_mutex; this is achieved
> by moving the call of init_vp_index() into vmbus_process_offer().
>=20
> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
> ---
>  drivers/hv/channel_mgmt.c | 47 ++++++++++++++++++++++++++++-----------
>  drivers/hv/hv.c           |  7 +++---
>  2 files changed, 38 insertions(+), 16 deletions(-)
>=20

Reviewed-by: Michael Kelley <mikelley@microsoft.com>