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Date:   Tue, 8 Sep 2020 10:32:49 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Joe Perches <joe@...ches.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 2/4] drivers core: Remove strcat uses around sysfs_emit
 and neaten

On Mon, Sep 07, 2020 at 10:58:06AM -0700, Joe Perches wrote:
> strcat is no longer necessary for sysfs_emit and sysfs_emit_at uses.
> 
> Convert the strcat uses to sysfs_emit calls and neaten other block
> uses of direct returns to use an intermediate const char *.
> 
> Signed-off-by: Joe Perches <joe@...ches.com>
> ---
>  drivers/base/cacheinfo.c   | 26 ++++++++++++++-------
>  drivers/base/core.c        | 10 ++++----
>  drivers/base/memory.c      | 47 ++++++++++++++++++--------------------
>  drivers/base/power/sysfs.c | 23 +++++++++++--------
>  4 files changed, 59 insertions(+), 47 deletions(-)
> 
> diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
> index 6a8c2b5881be..7b3608fb8700 100644
> --- a/drivers/base/cacheinfo.c
> +++ b/drivers/base/cacheinfo.c
> @@ -404,17 +404,23 @@ static ssize_t type_show(struct device *dev,
>  			 struct device_attribute *attr, char *buf)
>  {
>  	struct cacheinfo *this_leaf = dev_get_drvdata(dev);
> +	const char *type = NULL;
>  
>  	switch (this_leaf->type) {
>  	case CACHE_TYPE_DATA:
> -		return sysfs_emit(buf, "Data\n");
> +		type = "Data";
> +		break;
>  	case CACHE_TYPE_INST:
> -		return sysfs_emit(buf, "Instruction\n");
> +		type = "Instruction";
> +		break;
>  	case CACHE_TYPE_UNIFIED:
> -		return sysfs_emit(buf, "Unified\n");
> +		type = "Unified";
> +		break;
>  	default:
>  		return -EINVAL;
>  	}
> +
> +	return sysfs_emit(buf, "%s\n", type);
>  }

This function is now longer, with an assignment that is not needed
(type=NULL), so why make this "cleanup"?

>  
>  static ssize_t allocation_policy_show(struct device *dev,
> @@ -422,15 +428,19 @@ static ssize_t allocation_policy_show(struct device *dev,
>  {
>  	struct cacheinfo *this_leaf = dev_get_drvdata(dev);
>  	unsigned int ci_attr = this_leaf->attributes;
> -	int n = 0;
> +	const char *type = NULL;

It's a policy, not a type.

>  
>  	if ((ci_attr & CACHE_READ_ALLOCATE) && (ci_attr & CACHE_WRITE_ALLOCATE))
> -		n = sysfs_emit(buf, "ReadWriteAllocate\n");
> +		type = "ReadWriteAllocate";
>  	else if (ci_attr & CACHE_READ_ALLOCATE)
> -		n = sysfs_emit(buf, "ReadAllocate\n");
> +		type = "ReadAllocate";
>  	else if (ci_attr & CACHE_WRITE_ALLOCATE)
> -		n = sysfs_emit(buf, "WriteAllocate\n");
> -	return n;
> +		type = "WriteAllocate";
> +
> +	if (!type)
> +		return 0;
> +
> +	return sysfs_emit(buf, "%s\n", type);
>  }

Overall, this is a bit nicer, thanks.


>  
>  static ssize_t write_policy_show(struct device *dev,
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index fdadfa047968..2314a4e541b4 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -267,16 +267,16 @@ static ssize_t auto_remove_on_show(struct device *dev,
>  				   struct device_attribute *attr, char *buf)
>  {
>  	struct device_link *link = to_devlink(dev);
> -	char *str;
> +	char *type;
>  
>  	if (link->flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
> -		str = "supplier unbind";
> +		type = "supplier unbind";
>  	else if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER)
> -		str = "consumer unbind";
> +		type = "consumer unbind";
>  	else
> -		str = "never";
> +		type = "never";
>  
> -	return sysfs_emit(buf, "%s\n", str);
> +	return sysfs_emit(buf, "%s\n", type);

This isn't a "type", it is just a string :(


>  }
>  static DEVICE_ATTR_RO(auto_remove_on);
>  
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index 2fdab1ea036b..b559f2b1d1ff 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -139,7 +139,7 @@ static ssize_t state_show(struct device *dev, struct device_attribute *attr,
>  			  char *buf)
>  {
>  	struct memory_block *mem = to_memory_block(dev);
> -	ssize_t len = 0;
> +	const char *type;
>  
>  	/*
>  	 * We can probably put these states in a nice little array
> @@ -147,22 +147,20 @@ static ssize_t state_show(struct device *dev, struct device_attribute *attr,
>  	 */
>  	switch (mem->state) {
>  	case MEM_ONLINE:
> -		len = sysfs_emit(buf, "online\n");
> +		type = "online";
>  		break;
>  	case MEM_OFFLINE:
> -		len = sysfs_emit(buf, "offline\n");
> +		type = "offline";
>  		break;
>  	case MEM_GOING_OFFLINE:
> -		len = sysfs_emit(buf, "going-offline\n");
> +		type = "going-offline";
>  		break;
>  	default:
> -		len = sysfs_emit(buf, "ERROR-UNKNOWN-%ld\n",
> -				 mem->state);
>  		WARN_ON(1);
> -		break;
> +		return sysfs_emit(buf, "ERROR-UNKNOWN-%ld\n", mem->state);
>  	}
>  
> -	return len;
> +	return sysfs_emit(buf, "%s\n", type);

Again, not a type, it's a state.  And you did not merge all sysfs_emit()
calls into one here, so it's messier now, don't you think?

>  }
>  
>  int memory_notify(unsigned long val, void *v)
> @@ -307,17 +305,16 @@ static ssize_t phys_device_show(struct device *dev,
>  }
>  
>  #ifdef CONFIG_MEMORY_HOTREMOVE
> -static void print_allowed_zone(char *buf, int nid, unsigned long start_pfn,
> -		unsigned long nr_pages, int online_type,
> -		struct zone *default_zone)
> +static int print_allowed_zone(char *buf, int len, int nid,
> +			      unsigned long start_pfn, unsigned long nr_pages,
> +			      int online_type, struct zone *default_zone)

Unrelated change :(

>  {
>  	struct zone *zone;
>  
>  	zone = zone_for_pfn_range(online_type, nid, start_pfn, nr_pages);
> -	if (zone != default_zone) {
> -		strcat(buf, " ");
> -		strcat(buf, zone->name);
> -	}
> +	if (zone == default_zone)
> +		return 0;
> +	return sysfs_emit_at(buf, len, " %s", zone->name);
>  }

Nicer looking, thanks.

>  
>  static ssize_t valid_zones_show(struct device *dev,
> @@ -327,6 +324,7 @@ static ssize_t valid_zones_show(struct device *dev,
>  	unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
>  	unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
>  	struct zone *default_zone;
> +	int len = 0;
>  	int nid;
>  
>  	/*
> @@ -341,24 +339,23 @@ static ssize_t valid_zones_show(struct device *dev,
>  		default_zone = test_pages_in_a_zone(start_pfn,
>  						    start_pfn + nr_pages);
>  		if (!default_zone)
> -			return sysfs_emit(buf, "none\n");
> -		strcat(buf, default_zone->name);
> +			return sysfs_emit(buf, "%s\n", "none");
> +		len += sysfs_emit_at(buf, len, "%s", default_zone->name);
>  		goto out;
>  	}
>  
>  	nid = mem->nid;
>  	default_zone = zone_for_pfn_range(MMOP_ONLINE, nid, start_pfn,
>  					  nr_pages);
> -	strcat(buf, default_zone->name);
>  
> -	print_allowed_zone(buf, nid, start_pfn, nr_pages, MMOP_ONLINE_KERNEL,
> -			default_zone);
> -	print_allowed_zone(buf, nid, start_pfn, nr_pages, MMOP_ONLINE_MOVABLE,
> -			default_zone);
> +	len += sysfs_emit_at(buf, len, "%s", default_zone->name);
> +	len += print_allowed_zone(buf, len, nid, start_pfn, nr_pages,
> +				  MMOP_ONLINE_KERNEL, default_zone);
> +	len += print_allowed_zone(buf, len, nid, start_pfn, nr_pages,
> +				  MMOP_ONLINE_MOVABLE, default_zone);
>  out:
> -	strcat(buf, "\n");
> -
> -	return strlen(buf);
> +	len += sysfs_emit_at(buf, len, "%s", "\n");
> +	return len;

This is better.

>  }
>  static DEVICE_ATTR_RO(valid_zones);
>  #endif
> diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
> index 4276b792d0aa..c3d303c4c9c2 100644
> --- a/drivers/base/power/sysfs.c
> +++ b/drivers/base/power/sysfs.c
> @@ -255,9 +255,9 @@ static ssize_t pm_qos_latency_tolerance_us_show(struct device *dev,
>  	s32 value = dev_pm_qos_get_user_latency_tolerance(dev);
>  
>  	if (value < 0)
> -		return sysfs_emit(buf, "auto\n");
> +		return sysfs_emit(buf, "%s\n", "auto");
>  	if (value == PM_QOS_LATENCY_ANY)
> -		return sysfs_emit(buf, "any\n");
> +		return sysfs_emit(buf, "%s\n", "any");
>  
>  	return sysfs_emit(buf, "%d\n", value);
>  }

Unrelated change :(

> @@ -538,13 +538,18 @@ static DEVICE_ATTR_RO(runtime_active_kids);
>  static ssize_t runtime_enabled_show(struct device *dev,
>  				    struct device_attribute *attr, char *buf)
>  {
> -	if (dev->power.disable_depth && (dev->power.runtime_auto == false))
> -		return sysfs_emit(buf, "disabled & forbidden\n");
> -	if (dev->power.disable_depth)
> -		return sysfs_emit(buf, "disabled\n");
> -	if (dev->power.runtime_auto == false)
> -		return sysfs_emit(buf, "forbidden\n");
> -	return sysfs_emit(buf, "enabled\n");
> +	const char *type;
> +
> +	if (dev->power.disable_depth && !dev->power.runtime_auto)
> +		type = "disabled & forbidden";
> +	else if (dev->power.disable_depth)
> +		type = "disabled";
> +	else if (!dev->power.runtime_auto)
> +		type = "forbidden";
> +	else
> +		type = "enabled";
> +
> +	return sysfs_emit(buf, "%s\n", type);

It's not a type :(

thanks,

greg k-h

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