netdev - Re: [PATCH iwl-next v2 1/5] e1000: drop unnecessary constant casts to u16

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Message-ID: <20250708190635.GW452973@horms.kernel.org>
Date: Tue, 8 Jul 2025 20:06:35 +0100
From: Simon Horman <horms@...nel.org>
To: Jacek Kowalski <jacek@...ekk.info>
Cc: Tony Nguyen <anthony.l.nguyen@...el.com>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org
Subject: Re: [PATCH iwl-next v2 1/5] e1000: drop unnecessary constant casts
 to u16

On Tue, Jul 08, 2025 at 10:16:52AM +0200, Jacek Kowalski wrote:
> Remove unnecessary casts of constant values to u16.
> Let the C type system do it's job.
> 
> Signed-off-by: Jacek Kowalski <Jacek@...ekk.info>
> Suggested-by: Simon Horman <horms@...nel.org>
> ---
>  drivers/net/ethernet/intel/e1000/e1000_ethtool.c | 2 +-
>  drivers/net/ethernet/intel/e1000/e1000_hw.c      | 4 ++--
>  drivers/net/ethernet/intel/e1000/e1000_main.c    | 2 +-
>  3 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/e1000/e1000_ethtool.c b/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
> index d06d29c6c037..d152026a027b 100644
> --- a/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
> +++ b/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
> @@ -806,7 +806,7 @@ static int e1000_eeprom_test(struct e1000_adapter *adapter, u64 *data)
>  	}
>  
>  	/* If Checksum is not Correct return error else test passed */
> -	if ((checksum != (u16)EEPROM_SUM) && !(*data))
> +	if ((checksum != EEPROM_SUM) && !(*data))
>  		*data = 2;

nit: If there is a v3 for some other reason, then I think
     you could also drop the inner parentheses here.

>  
>  	return *data;
> diff --git a/drivers/net/ethernet/intel/e1000/e1000_hw.c b/drivers/net/ethernet/intel/e1000/e1000_hw.c
> index f9328f2e669f..0e5de52b1067 100644
> --- a/drivers/net/ethernet/intel/e1000/e1000_hw.c
> +++ b/drivers/net/ethernet/intel/e1000/e1000_hw.c
> @@ -3970,7 +3970,7 @@ s32 e1000_validate_eeprom_checksum(struct e1000_hw *hw)
>  		return E1000_SUCCESS;
>  
>  #endif
> -	if (checksum == (u16)EEPROM_SUM)
> +	if (checksum == EEPROM_SUM)
>  		return E1000_SUCCESS;
>  	else {
>  		e_dbg("EEPROM Checksum Invalid\n");
> @@ -3997,7 +3997,7 @@ s32 e1000_update_eeprom_checksum(struct e1000_hw *hw)
>  		}
>  		checksum += eeprom_data;
>  	}
> -	checksum = (u16)EEPROM_SUM - checksum;
> +	checksum = EEPROM_SUM - checksum;
>  	if (e1000_write_eeprom(hw, EEPROM_CHECKSUM_REG, 1, &checksum) < 0) {
>  		e_dbg("EEPROM Write Error\n");
>  		return -E1000_ERR_EEPROM;
> diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c
> index d8595e84326d..09acba2ed483 100644
> --- a/drivers/net/ethernet/intel/e1000/e1000_main.c
> +++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
> @@ -313,7 +313,7 @@ static void e1000_update_mng_vlan(struct e1000_adapter *adapter)
>  		} else {
>  			adapter->mng_vlan_id = E1000_MNG_VLAN_NONE;
>  		}
> -		if ((old_vid != (u16)E1000_MNG_VLAN_NONE) &&
> +		if ((old_vid != E1000_MNG_VLAN_NONE) &&

Ditto.

But more importantly, both Clang 20.1.7 W=1 builds (or at any rate, builds
with -Wtautological-constant-out-of-range-compare), and Smatch complain
that the comparison above is now always true because E1000_MNG_VLAN_NONE is
-1, while old_vid is unsigned.

Perhaps E1000_MNG_VLAN_NONE should be updated to be UINT16_MAX?


>  		    (vid != old_vid) &&
>  		    !test_bit(old_vid, adapter->active_vlans))
>  			e1000_vlan_rx_kill_vid(netdev, htons(ETH_P_8021Q),
> -- 
> 2.47.2
>