[PATCH] ocxl: fix pci device refcount leak when calling get_function_0()

[Christophe Leroy]

Le 19/11/2022 à 15:44, Yang Yingliang a écrit :
> As comment of pci_get_domain_bus_and_slot() says, it returns
> a pci device with refcount increment, so when finish using it,
> pci_dev_put() needs be called.
> 
> In get_dvsec_vendor0(), in normal path, the returned pci device
> is passed to dev0, so after using dev0 in the callers, it need
> be put, in error path, pci_dev_put() also needs be called.
> 
> pci_get_domain_bus_and_slot() is called when PCI_FUNC() returns
> non-zero, check this before put.
> 
> Fixes: 87db7579ebd5 ("ocxl: control via sysfs whether the FPGA is reloaded on a link reset")
> Signed-off-by: Yang Yingliang <yangyingliang at huawei.com>
> ---
>   drivers/misc/ocxl/config.c | 11 ++++++++++-
>   1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/ocxl/config.c b/drivers/misc/ocxl/config.c
> index e401a51596b9..4da5a2b8514c 100644
> --- a/drivers/misc/ocxl/config.c
> +++ b/drivers/misc/ocxl/config.c
> @@ -196,16 +196,21 @@ static int read_dvsec_vendor(struct pci_dev *dev)
>   static int get_dvsec_vendor0(struct pci_dev *dev, struct pci_dev **dev0,
>   			     int *out_pos)
>   {
> +	bool need_put;
>   	int pos;
>   
>   	if (PCI_FUNC(dev->devfn) != 0) {
>   		dev = get_function_0(dev);
>   		if (!dev)
>   			return -1;
> +		need_put = true;

Why introduce that 'need_put' boolean ? Why not just use 
PCI_FUNC(dev->devfn) != 0 as you do in other places ?

>   	}
>   	pos = find_dvsec(dev, OCXL_DVSEC_VENDOR_ID);
> -	if (!pos)
> +	if (!pos) {
> +		if (need_put)
> +			pci_dev_put(dev);
>   		return -1;
> +	}
>   	*dev0 = dev;
>   	*out_pos = pos;
>   	return 0;
> @@ -222,6 +227,8 @@ int ocxl_config_get_reset_reload(struct pci_dev *dev, int *val)
>   
>   	pci_read_config_dword(dev0, pos + OCXL_DVSEC_VENDOR_RESET_RELOAD,
>   			      &reset_reload);
> +	if (PCI_FUNC(dev->devfn) != 0)

The != 0 is useless, just do:

	if (PCI_FUNC(dev->devfn))

> +		pci_dev_put(dev0);
>   	*val = !!(reset_reload & BIT(0));
>   	return 0;
>   }
> @@ -243,6 +250,8 @@ int ocxl_config_set_reset_reload(struct pci_dev *dev, int val)
>   		reset_reload &= ~BIT(0);
>   	pci_write_config_dword(dev0, pos + OCXL_DVSEC_VENDOR_RESET_RELOAD,
>   			       reset_reload);
> +	if (PCI_FUNC(dev->devfn) != 0)

Same

> +		pci_dev_put(dev0);
>   	return 0;
>   }
>