Re: [PATCH v3 3/8] drivers/base/memory: store mapping between MMOP_* and string in an array

From: Baoquan He <bhe@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linuxppc-dev@lists.ozlabs.org, linux-hyperv@vger.kernel.org,
	Wei Yang <richard.weiyang@gmail.com>,
	Michal Hocko <mhocko@suse.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>,
	Oscar Salvador <osalvador@suse.de>,
	"Rafael J. Wysocki" <rafael@kernel.org>
Subject: Re: [PATCH v3 3/8] drivers/base/memory: store mapping between MMOP_* and string in an array
Date: Fri, 20 Mar 2020 15:36:53 +0800	[thread overview]
Message-ID: <20200320073653.GE2987@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20200319131221.14044-4-david@redhat.com>

On 03/19/20 at 02:12pm, David Hildenbrand wrote:
> Let's use a simple array which we can reuse soon. While at it, move the
> string->mmop conversion out of the device hotplug lock.
> 
> Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
> Acked-by: Michal Hocko <mhocko@suse.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Baoquan He <bhe@redhat.com>
> Cc: Wei Yang <richard.weiyang@gmail.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  drivers/base/memory.c | 38 +++++++++++++++++++++++---------------
>  1 file changed, 23 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index e7e77cafef80..8a7f29c0bf97 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -28,6 +28,24 @@
>  
>  #define MEMORY_CLASS_NAME	"memory"
>  
> +static const char *const online_type_to_str[] = {
> +	[MMOP_OFFLINE] = "offline",
> +	[MMOP_ONLINE] = "online",
> +	[MMOP_ONLINE_KERNEL] = "online_kernel",
> +	[MMOP_ONLINE_MOVABLE] = "online_movable",
> +};
> +
> +static int memhp_online_type_from_str(const char *str)
> +{
> +	int i;

I would change it as: 

	for (int i = 0; i < ARRAY_SIZE(online_type_to_str); i++) {

> +
> +	for (i = 0; i < ARRAY_SIZE(online_type_to_str); i++) {
> +		if (sysfs_streq(str, online_type_to_str[i]))
> +			return i;
> +	}
> +	return -EINVAL;
> +}
> +
>  #define to_memory_block(dev) container_of(dev, struct memory_block, dev)
>  
>  static int sections_per_block;
> @@ -236,26 +254,17 @@ static int memory_subsys_offline(struct device *dev)
>  static ssize_t state_store(struct device *dev, struct device_attribute *attr,
>  			   const char *buf, size_t count)
>  {
> +	const int online_type = memhp_online_type_from_str(buf);
>  	struct memory_block *mem = to_memory_block(dev);
> -	int ret, online_type;
> +	int ret;
> +
> +	if (online_type < 0)
> +		return -EINVAL;
>  
>  	ret = lock_device_hotplug_sysfs();
>  	if (ret)
>  		return ret;
>  
> -	if (sysfs_streq(buf, "online_kernel"))
> -		online_type = MMOP_ONLINE_KERNEL;
> -	else if (sysfs_streq(buf, "online_movable"))
> -		online_type = MMOP_ONLINE_MOVABLE;
> -	else if (sysfs_streq(buf, "online"))
> -		online_type = MMOP_ONLINE;
> -	else if (sysfs_streq(buf, "offline"))
> -		online_type = MMOP_OFFLINE;
> -	else {
> -		ret = -EINVAL;
> -		goto err;
> -	}
> -
>  	switch (online_type) {
>  	case MMOP_ONLINE_KERNEL:
>  	case MMOP_ONLINE_MOVABLE:
> @@ -271,7 +280,6 @@ static ssize_t state_store(struct device *dev, struct device_attribute *attr,
>  		ret = -EINVAL; /* should never happen */
>  	}
>  
> -err:
>  	unlock_device_hotplug();
>  
>  	if (ret < 0)
> -- 
> 2.24.1
>