linux-kernel - RE: [PATCH] Drivers: hv: vmbus: Use raw_smp_processor_id() in vmbus

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Date:   Thu, 30 Aug 2018 17:27:08 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     KY Srinivasan <kys@...rosoft.com>,
        "'gregkh@...uxfoundation.org'" <gregkh@...uxfoundation.org>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>
CC:     "'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
        "'driverdev-devel@...uxdriverproject.org'" 
        <driverdev-devel@...uxdriverproject.org>,
        "'olaf@...fle.de'" <olaf@...fle.de>,
        "'apw@...onical.com'" <apw@...onical.com>,
        "'jasowang@...hat.com'" <jasowang@...hat.com>,
        vkuznets <vkuznets@...hat.com>,
        "'marcelo.cerri@...onical.com'" <marcelo.cerri@...onical.com>
Subject: RE: [PATCH] Drivers: hv: vmbus: Use raw_smp_processor_id() in
 vmbus_connect()

> From: KY Srinivasan
> Sent: Thursday, August 30, 2018 09:28
> ...
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> @@ -119,8 +119,9 @@ static int vmbus_negotiate_version(struct
> vmbus_channel_msginfo *msginfo,
>          */
>    if (version >= VERSION_WIN8_1) {
>        msg->target_vcpu =
> -            hv_cpu_number_to_vp_number(smp_processor_id());
> -       vmbus_connection.connect_cpu = smp_processor_id();

> +       hv_cpu_number_to_vp_number(get_cpu());
> +       vmbus_connection.connect_cpu = msg->target_vcpu;
> +       put_cpu();

While the warning " BUG: using smp_processor_id() in preemptible" can also
be avoided, the line 
+	vmbus_connection.connect_cpu = msg->target_vcpu;
seems incorrect, as the "connect_cpu" should reflect Linux CPU numbering
rather than Hyper-V's vCPU numbering.

-- Dexuan