netdev - RE: [PATCH net-next] net: txgbe: Avoid passing uninitialised parameter to pci_wake_from

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Date: Tue, 6 Jun 2023 16:18:07 +0800
From: Jiawen Wu <jiawenwu@...stnetic.com>
To: "'Simon Horman'" <horms@...nel.org>,
	"'Jakub Kicinski'" <kuba@...nel.org>,
	"'David S. Miller'" <davem@...emloft.net>,
	"'Eric Dumazet'" <edumazet@...gle.com>,
	"'Paolo Abeni'" <pabeni@...hat.com>
Cc: "'Mengyuan Lou'" <mengyuanlou@...-swift.com>,
	"'Dan Carpenter'" <dan.carpenter@...aro.com>,
	<netdev@...r.kernel.org>
Subject: RE: [PATCH net-next] net: txgbe: Avoid passing uninitialised parameter to pci_wake_from_d3()

On Monday, June 5, 2023 10:20 PM, Simon Horman wrote:
> txgbe_shutdown() relies on txgbe_dev_shutdown() to initialise
> wake by passing it by reference. However, txgbe_dev_shutdown()
> doesn't use this parameter at all.
> 
> wake is then passed uninitialised by txgbe_dev_shutdown()
> to pci_wake_from_d3().
> 
> Resolve this problem by:
> * Removing the unused parameter from txgbe_dev_shutdown()
> * Removing the uninitialised variable wake from txgbe_dev_shutdown()
> * Passing false to pci_wake_from_d3() - this assumes that
>   although uninitialised wake was in practice false (0).
> 
> I'm not sure that this counts as a bug, as I'm not sure that
> it manifests in any unwanted behaviour. But in any case, the issue
> was introduced by:

Thanks for the fix. These are some redundant codes for a feature that has
not yet been implemented.
Reviewed-by: Jiawen Wu <jiawenwu@...stnetic.com>

> 
>   bbd22f34b47c ("net: txgbe: Avoid passing uninitialised parameter to pci_wake_from_d3()")
> 
> Flagged by Smatch as:
> 
>   .../txgbe_main.c:486 txgbe_shutdown() error: uninitialized symbol 'wake'.
> 
> No functional change intended.
> Compile tested only.
> 
> Signed-off-by: Simon Horman <horms@...nel.org>
> ---
>  drivers/net/ethernet/wangxun/txgbe/txgbe_main.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/ethernet/wangxun/txgbe/txgbe_main.c b/drivers/net/ethernet/wangxun/txgbe/txgbe_main.c
> index 0f0d9fa1cde1..cfe47f3d2503 100644
> --- a/drivers/net/ethernet/wangxun/txgbe/txgbe_main.c
> +++ b/drivers/net/ethernet/wangxun/txgbe/txgbe_main.c
> @@ -457,7 +457,7 @@ static int txgbe_close(struct net_device *netdev)
>  	return 0;
>  }
> 
> -static void txgbe_dev_shutdown(struct pci_dev *pdev, bool *enable_wake)
> +static void txgbe_dev_shutdown(struct pci_dev *pdev)
>  {
>  	struct wx *wx = pci_get_drvdata(pdev);
>  	struct net_device *netdev;
> @@ -477,12 +477,10 @@ static void txgbe_dev_shutdown(struct pci_dev *pdev, bool *enable_wake)
> 
>  static void txgbe_shutdown(struct pci_dev *pdev)
>  {
> -	bool wake;
> -
> -	txgbe_dev_shutdown(pdev, &wake);
> +	txgbe_dev_shutdown(pdev);
> 
>  	if (system_state == SYSTEM_POWER_OFF) {
> -		pci_wake_from_d3(pdev, wake);
> +		pci_wake_from_d3(pdev, false);
>  		pci_set_power_state(pdev, PCI_D3hot);
>  	}
>  }