linux-kernel - Re: [PATCH v5 04/10] pci: don't disable msi/msix at shutdown

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Message-ID: <20150402035449.GG15412@fam-t430.nay.redhat.com>
Date:	Thu, 2 Apr 2015 11:54:49 +0800
From:	Fam Zheng <famz@...hat.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-pci@...r.kernel.org, Yinghai Lu <yhlu.kernel.send@...il.com>,
	Yijing Wang <wangyijing@...wei.com>,
	Ulrich Obergfell <uobergfe@...hat.com>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: [PATCH v5 04/10] pci: don't disable msi/msix at shutdown

On Sun, 03/29 17:04, Michael S. Tsirkin wrote:
> This partially reverts commit d52877c7b1afb8c37ebe17e2005040b79cb618b0:
> 	"pci/irq: let pci_device_shutdown to call pci_msi_shutdown v2"
> 
> It's un-necessary now that we disable msi at start, and it actually
> turns out to cause problems: some device drivers don't register a level
> interrupt handler when they detect msi/msix capability, switching off
> msi while device is going causes device to assert a level interrupt
> which is never de-asserted, causing a kernel hang.
> 
> In particular, this was observed with virtio.
> 
> Cc: Yinghai Lu <yhlu.kernel.send@...il.com>
> Cc: Ulrich Obergfell <uobergfe@...hat.com>
> Cc: Rusty Russell <rusty@...tcorp.com.au>
> Reported-by: Fam Zheng <famz@...hat.com>
> Signed-off-by: Michael S. Tsirkin <mst@...hat.com>

Reviewed-by: Fam Zheng <famz@...hat.com>
Tested-by: Fam Zheng <famz@...hat.com>

> ---
>  drivers/pci/pci-driver.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 3cb2210..38a602c 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -450,8 +450,6 @@ static void pci_device_shutdown(struct device *dev)
>  
>  	if (drv && drv->shutdown)
>  		drv->shutdown(pci_dev);
> -	pci_msi_shutdown(pci_dev);
> -	pci_msix_shutdown(pci_dev);
>  
>  #ifdef CONFIG_KEXEC
>  	/*
> -- 
> MST
> 
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