Re: [PATCH iwl-net 3/3] ice: Reject pin requests with unsupported flags

[Simon Horman <horms@kernel.org>]

On Tue, Jun 18, 2024 at 12:41:38PM +0200, Karol Kolacinski wrote:
> From: Jacob Keller <jacob.e.keller@intel.com>
> 
> The driver receives requests for configuring pins via the .enable
> callback of the PTP clock object. These requests come into the driver
> with flags which modify the requested behavior from userspace. Current
> implementation in ice does not reject flags that it doesn't support.
> This causes the driver to incorrectly apply requests with such flags as
> PTP_PEROUT_DUTY_CYCLE, or any future flags added by the kernel which it
> is not yet aware of.
> 
> Fix this by properly validating flags in both ice_ptp_cfg_perout and
> ice_ptp_cfg_extts. Ensure that we check by bit-wise negating supported
> flags rather than just checking and rejecting known un-supported flags.
> This is preferable, as it ensures better compatibility with future
> kernels.
> 
> Fixes: 172db5f91d5f ("ice: add support for auxiliary input/output pins")
> Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
> Signed-off-by: Karol Kolacinski <karol.kolacinski@intel.com>

Hi Jacob and Karol,

Some minor feedback from my side.

...

> diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.c b/drivers/net/ethernet/intel/ice/ice_ptp.c
> index b952cad42f92..5fa377786f4c 100644
> --- a/drivers/net/ethernet/intel/ice/ice_ptp.c
> +++ b/drivers/net/ethernet/intel/ice/ice_ptp.c
> @@ -1591,14 +1591,23 @@ void ice_ptp_extts_event(struct ice_pf *pf)
>   * @store: If set to true, the values will be stored
>   *
>   * Configure an external timestamp event on the requested channel.
> -  */
> -static void ice_ptp_cfg_extts(struct ice_pf *pf, unsigned int chan,
> -			      struct ice_extts_channel *config, bool store)
> + *
> + * Return: 0 on sucess, -EOPNOTUSPP on unsupported flags

nit: success

     Flagged by checkpatch.pl --codespell

> + */
> +static int ice_ptp_cfg_extts(struct ice_pf *pf, unsigned int chan,
> +			     struct ice_extts_channel *config, bool store)
>  {
>  	u32 func, aux_reg, gpio_reg, irq_reg;
>  	struct ice_hw *hw = &pf->hw;
>  	u8 tmr_idx;
>  
> +	/* Reject requests with unsupported flags */
> +	if (config->flags & ~(PTP_ENABLE_FEATURE |
> +			      PTP_RISING_EDGE |
> +			      PTP_FALLING_EDGE |
> +			      PTP_STRICT_FLAGS))
> +	return -EOPNOTSUPP;

The line above should to be indented one more tab.
Clearly this makes no difference at run-time,
but it takes a while (for me) to parse things as-is.

...

> @@ -1697,6 +1708,9 @@ static int ice_ptp_cfg_clkout(struct ice_pf *pf, unsigned int chan,
>  	u32 func, val, gpio_pin;
>  	u8 tmr_idx;
>  
> +	if (config->flags & ~PTP_PEROUT_PHASE)
> +		return -EOPNOTSUPP;

A little further down in this function it is assumed that config may
be NULL. So I think the code above needs to be updated to take that
into account too.

Flagged by Smatch.

...