linux-kernel - Re: [PATCH v1 2/3] EDAC, pnd2: Apply bit macros and helpers where it makes sense

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Message-Id: <20231116082857.89714-1-qiuxu.zhuo@intel.com>
Date:   Thu, 16 Nov 2023 16:28:57 +0800
From:   Qiuxu Zhuo <qiuxu.zhuo@...el.com>
To:     andriy.shevchenko@...ux.intel.com
Cc:     bp@...en8.de, james.morse@....com, linux-edac@...r.kernel.org,
        linux-kernel@...r.kernel.org, mchehab@...nel.org, rric@...nel.org,
        tony.luck@...el.com, qiuxu.zhuo@...el.com
Subject: Re: [PATCH v1 2/3] EDAC, pnd2: Apply bit macros and helpers where it makes sense

> From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ...
> 
> Apply bit macros (BIT()/BIT_ULL()/GENMASK()/etc) and helpers
> (is_power_of_2()/for_each_set_bit()/etc) where it makes sense.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/edac/pnd2_edac.c | 39 ++++++++++++++++++---------------------
>  1 file changed, 18 insertions(+), 21 deletions(-)
> 
> ...
> @@ -328,7 +328,7 @@ static void mk_region_mask(char *name, struct region *rp, u64 base, u64 mask)
>  		pr_info(FW_BUG "MOT mask cannot be zero\n");
>  		return;
>  	}
> -	if (mask != GENMASK_ULL(PND_MAX_PHYS_BIT, __ffs(mask))) {
> +	if (is_power_of_2(mask)) {

The original code verifies whether the 'mask' contains consecutive 1s between the
most significant bit 'PND_MAX_PHYS_BIT' and the least significant bit '__ffs(mask)'.
It isn't the check whether the 'mask' is power of 2.

>  		pr_info(FW_BUG "MOT mask not power of two\n");

This original pr_info "MOT mask not power of two" is incorrect.
May need to update it like:

  		pr_info(FW_BUG "MOT mask is invalid\n");

> ...
>  /* addrdec values */
>  #define AMAP_1KB	0
> @@ -1061,12 +1061,13 @@ static int check_channel(int ch)
>  
>  static int apl_check_ecc_active(void)
>  {
> -	int	i, ret = 0;
> +	unsigned int i;
> +	int ret;

Need to initialize the 'ret' to 0.

The LKP reported this warnning as well:
https://lore.kernel.org/all/202311160352.PfYDQfkU-lkp@intel.com/

>  
>  	/* Check dramtype and ECC mode for each present DIMM */
> -	for (i = 0; i < APL_NUM_CHANNELS; i++)
> -		if (chan_mask & BIT(i))
> -			ret += check_channel(i);
> +	for_each_set_bit(i, &chan_mask, APL_NUM_CHANNELS)
> +		ret += check_channel(i);
> +
>  	return ret ? -EINVAL : 0;
>  }
>  ...

Thanks!
-Qiuxu