linux-kernel - RE: [PATCH v2 3/3] Drivers: hv: vmbus: setup irq after synic is initialized

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Message-ID: <BY2PR0301MB0711D1B7FFE8BEE04BD4DD55A0D30@BY2PR0301MB0711.namprd03.prod.outlook.com>
Date:	Sun, 3 May 2015 01:58:47 +0000
From:	KY Srinivasan <kys@...rosoft.com>
To:	Vitaly Kuznetsov <vkuznets@...hat.com>
CC:	Haiyang Zhang <haiyangz@...rosoft.com>,
	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Dexuan Cui <decui@...rosoft.com>,
	"Dan Carpenter" <dan.carpenter@...cle.com>
Subject: RE: [PATCH v2 3/3] Drivers: hv: vmbus: setup irq after synic is
 initialized



> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@...hat.com]
> Sent: Tuesday, April 21, 2015 9:22 AM
> To: KY Srinivasan
> Cc: Haiyang Zhang; devel@...uxdriverproject.org; linux-
> kernel@...r.kernel.org; Dexuan Cui; Dan Carpenter
> Subject: [PATCH v2 3/3] Drivers: hv: vmbus: setup irq after synic is initialized
> 
> vmbus_isr() uses synic pages which are being setup in hv_synic_alloc(), we
> need to register this irq handler only after we allocate all the required
> pages.

Why? Until we tell the hypervisor to route the vmbus interrupts on the specified vector,
no vmbus interrupts will be delivered and this is done in the function hv_synic_init().
So, the only requirement here is that all of the irq plumbing and allocations be done 
before we enable the synthetic interrupt controller and register the vector with the
hypervisor. What am I missing.

Regards,

K. Y
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
>  drivers/hv/vmbus_drv.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index cf20400..e922804 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -822,11 +822,12 @@ static int vmbus_bus_init(int irq)
>  	if (ret)
>  		goto err_cleanup;
> 
> -	hv_setup_vmbus_irq(vmbus_isr);
> -
>  	ret = hv_synic_alloc();
>  	if (ret)
>  		goto err_alloc;
> +
> +	hv_setup_vmbus_irq(vmbus_isr);
> +
>  	/*
>  	 * Initialize the per-cpu interrupt state and
>  	 * connect to the host.
> --
> 1.9.3

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