linux-kernel - Re: [PATCH v1 4/7] fpga: dfl: fix VF creation when ports have no local BAR space

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Date:   Tue, 15 Feb 2022 07:50:40 -0800
From:   Tom Rix <trix@...hat.com>
To:     Tianfei zhang <tianfei.zhang@...el.com>, hao.wu@...el.com,
        mdf@...nel.org, yilun.xu@...el.com, linux-fpga@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     corbet@....net, Matthew Gerlach <matthew.gerlach@...ux.intel.com>
Subject: Re: [PATCH v1 4/7] fpga: dfl: fix VF creation when ports have no
 local BAR space


On 2/14/22 3:26 AM, Tianfei zhang wrote:
> From: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
>
> When a port is not connected to the same PCIe endpoint as
> the FME, the port does not need to be released before being
> virtualized.  Fix VF creation code to handle this new use
Similar, how does this fit in with iofs, this looks like it would not be 
valid for the existing cards
> case.
>
> Signed-off-by: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
> Signed-off-by: Tianfei Zhang <tianfei.zhang@...el.com>
> ---
>   drivers/fpga/dfl.c | 11 +++++++++--
>   1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> index 26f8cf890700..cfc539a656f0 100644
> --- a/drivers/fpga/dfl.c
> +++ b/drivers/fpga/dfl.c
> @@ -1705,15 +1705,22 @@ EXPORT_SYMBOL_GPL(dfl_fpga_cdev_config_ports_pf);
>   int dfl_fpga_cdev_config_ports_vf(struct dfl_fpga_cdev *cdev, int num_vfs)
>   {
>   	struct dfl_feature_platform_data *pdata;
> -	int ret = 0;
> +	int ret = 0, port_count = 0;
>   
>   	mutex_lock(&cdev->lock);
> +
> +	list_for_each_entry(pdata, &cdev->port_dev_list, node) {
> +		if (pdata->dev)

This looks wrong,

pdata->dev is dereferenced below, if there is a case were (!pdata->dev) 
here there would be crash later.

> +			continue;
> +		port_count++;

how does this work when only some of the ports are handled in the new way ?

Tom

> +	}
> +
>   	/*
>   	 * can't turn multiple ports into 1 VF device, only 1 port for 1 VF
>   	 * device, so if released port number doesn't match VF device number,
>   	 * then reject the request with -EINVAL error code.
>   	 */
> -	if (cdev->released_port_num != num_vfs) {
> +	if (port_count && cdev->released_port_num != num_vfs) {
>   		ret = -EINVAL;
>   		goto done;
>   	}