netdev - Re: [PATCH net 2/3] ice: use int for n_per

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Date:   Wed,  9 Nov 2022 17:37:12 +0100
From:   Alexander Lobakin <alexandr.lobakin@...el.com>
To:     Jacob Keller <jacob.e.keller@...el.com>
Cc:     Alexander Lobakin <alexandr.lobakin@...el.com>,
        davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        edumazet@...gle.com, Tony Nguyen <anthony.l.nguyen@...el.com>,
        netdev@...r.kernel.org, richardcochran@...il.com,
        Gurucharan G <gurucharanx.g@...el.com>
Subject: Re: [PATCH net 2/3] ice: use int for n_per_out loop

From: Tony Nguyen <anthony.l.nguyen@...el.com>
Date: Tue,  8 Nov 2022 15:51:15 -0800

> From: Jacob Keller <jacob.e.keller@...el.com>
> 
> In ice_ptp_enable_all_clkout and ice_ptp_disable_all_clkout we use a uint
> for a for loop iterating over the n_per_out value from the struct
> ptp_clock_info. The struct member is a signed int, and the use of uint
> generates a -Wsign-compare warning:
> 
>   drivers/net/ethernet/intel/ice/ice_ptp.c: In function ‘ice_ptp_enable_all_clkout’:
>   drivers/net/ethernet/intel/ice/ice_ptp.c:1710:23: error: comparison of integer expressions of different signedness: ‘uint’ {aka ‘unsigned int’} and ‘int’ [-Werror=sign-compare]
>    1710 |         for (i = 0; i < pf->ptp.info.n_per_out; i++)
>         |                       ^
>   cc1: all warnings being treated as errors
> 
> While we don't generally compile with -Wsign-compare, its still a good idea

-Wsign-compare is disabled even on W=2.

> not to mix types. Fix the two functions to use a plain signed integer.

It's still a good idea to not use ints when values below zero are
not used. Here both @i's are used as iterators from zero and above.
The change is just pointless. I would even understand if you casted
::n_per_out to `u32` in the loop condition and -Wsign-compare was
enabled on W=1 or 2, but not this.

> 
> Fixes: 9ee313433c48 ("ice: restart periodic outputs around time changes")

...even more pointless to send it to net, not net-next, it doesn't
fix anything. If you manually enable the warning via KCFLAGS, you'll
see thousands of them.

> Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
> Tested-by: Gurucharan G <gurucharanx.g@...el.com> (A Contingent worker at Intel)
> Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
> ---
>  drivers/net/ethernet/intel/ice/ice_ptp.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.c b/drivers/net/ethernet/intel/ice/ice_ptp.c
> index 011b727ab190..be147fb641ae 100644
> --- a/drivers/net/ethernet/intel/ice/ice_ptp.c
> +++ b/drivers/net/ethernet/intel/ice/ice_ptp.c
> @@ -1688,7 +1688,7 @@ static int ice_ptp_cfg_clkout(struct ice_pf *pf, unsigned int chan,
>   */
>  static void ice_ptp_disable_all_clkout(struct ice_pf *pf)
>  {
> -	uint i;
> +	int i;
>  
>  	for (i = 0; i < pf->ptp.info.n_per_out; i++)
>  		if (pf->ptp.perout_channels[i].ena)
> @@ -1705,7 +1705,7 @@ static void ice_ptp_disable_all_clkout(struct ice_pf *pf)
>   */
>  static void ice_ptp_enable_all_clkout(struct ice_pf *pf)
>  {
> -	uint i;
> +	int i;
>  
>  	for (i = 0; i < pf->ptp.info.n_per_out; i++)
>  		if (pf->ptp.perout_channels[i].ena)
> -- 
> 2.35.1

Thanks,
Olek