linux-kernel - Re: [PATCH] PCI: stop crashing in pci_release

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Message-ID: <20180226205632.GB63171@bhelgaas-glaptop.roam.corp.google.com>
Date:   Mon, 26 Feb 2018 14:56:32 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Christian König 
        <ckoenig.leichtzumerken@...il.com>
Cc:     bhelgaas@...gle.com, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org
Subject: Re: [PATCH] PCI: stop crashing in pci_release_resource v2

On Wed, Feb 21, 2018 at 10:07:15AM +0100, Christian König wrote:
> Is it entirely possible that the BIOS wasn't able to assign resources to
> a device. In this case don't crash in pci_release_resource() when we try
> to resize the resource.
> 
> v2: keep printing the info that we try to release the BAR
> 
> Signed-off-by: Christian König <christian.koenig@....com>
> CC: stable@...r.kernel.org

I think we probably want this in v4.16, since it seems to be a fix for
8bb705e3e79d ("PCI: Add pci_resize_resource() for resizing BARs"),
which appeared in v4.15.

What does the crash look like?  I might include a few lines in the
changelog to help people find the fix.

I added a Fixes: tag and Andy's Reviewed-by already.

> ---
>  drivers/pci/setup-res.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
> index e815111f3f81..c0f091614805 100644
> --- a/drivers/pci/setup-res.c
> +++ b/drivers/pci/setup-res.c
> @@ -402,6 +402,10 @@ void pci_release_resource(struct pci_dev *dev, int resno)
>  	struct resource *res = dev->resource + resno;
>  
>  	dev_info(&dev->dev, "BAR %d: releasing %pR\n", resno, res);
> +
> +	if (!res->parent)
> +		return;
> +
>  	release_resource(res);
>  	res->end = resource_size(res) - 1;
>  	res->start = 0;
> -- 
> 2.14.1
>