Re: [PATCH 2/4] drivers core: Remove strcat uses around sysfs_emit and neaten

Greg Kroah-Hartman
2020-09-08T08:32:42Z

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@perches.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