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Message-ID: <20160805231507.GD4952@f23x64.localdomain>
Date: Fri, 5 Aug 2016 16:15:07 -0700
From: Darren Hart <dvhart@...radead.org>
To: Giedrius Statkevičius
<giedrius.statkevicius@...il.com>
Cc: corentin.chary@...il.com, acpi4asus-user@...ts.sourceforge.net,
platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] asus-laptop: get rid of parse_arg()
On Fri, Aug 05, 2016 at 11:57:10PM +0300, Giedrius Statkevičius wrote:
> parse_arg() duplicates the funcionality of kstrtoint() so use the latter
> function instead. There is no funcionality change except that in the
> case of input being too big -ERANGE will be returned instead of -EINVAL
> which is not bad because -ERANGE makes more sense here. The check for
> !count is already done by the sysfs core so no need to duplicate it
> again. Also, add some minor corrections to error handling to accommodate
> the change in return values (parse_arg returned count if everything
> succeeded whereas kstrtoint returns 0 in the same situation)
>
> As a result of this patch asus-laptop.ko size is reduced by almost 1%:
> add/remove: 0/1 grow/shrink: 1/6 up/down: 1/-149 (-148)
> function old new delta
> __UNIQUE_ID_vermagic0 69 70 +1
> ls_switch_store 133 117 -16
> ledd_store 175 159 -16
> display_store 157 141 -16
> ls_level_store 193 176 -17
> gps_store 200 178 -22
> sysfs_acpi_set.isra 148 125 -23
> parse_arg.part 39 - -39
> Total: Before=19160, After=19012, chg -0.77%
>
> Signed-off-by: Giedrius Statkevičius <giedrius.statkevicius@...il.com>
> ---
> drivers/platform/x86/asus-laptop.c | 77 ++++++++++++++++++--------------------
> 1 file changed, 36 insertions(+), 41 deletions(-)
>
> diff --git a/drivers/platform/x86/asus-laptop.c b/drivers/platform/x86/asus-laptop.c
> index 15f1311..28551f5 100644
> --- a/drivers/platform/x86/asus-laptop.c
> +++ b/drivers/platform/x86/asus-laptop.c
> @@ -932,30 +932,19 @@ static ssize_t infos_show(struct device *dev, struct device_attribute *attr,
> }
> static DEVICE_ATTR_RO(infos);
>
> -static int parse_arg(const char *buf, unsigned long count, int *val)
> -{
> - if (!count)
> - return 0;
> - if (count > 31)
> - return -EINVAL;
> - if (sscanf(buf, "%i", val) != 1)
> - return -EINVAL;
> - return count;
> -}
> -
> static ssize_t sysfs_acpi_set(struct asus_laptop *asus,
> const char *buf, size_t count,
> const char *method)
> {
> int rv, value;
>
> - rv = parse_arg(buf, count, &value);
> - if (rv <= 0)
> + rv = kstrtoint(buf, 0, &value);
> + if (rv < 0)
> return rv;
>
> if (write_acpi_int(asus->handle, method, value))
> return -ENODEV;
> - return rv;
> + return count;
This makes explicit what was hidden before - count is merely a range check, it
isn't used in parsing the string... I'm not sure if this is a problem, but it
caught my interest. If count is passed as 12, but buf only contains 3 character,
it may succeed and return 12. I suppose this is a failure in the caller, and
doesn't impact this function - unless the caller isn't expected to properly
terminate the string... but if that were the case, it would have failed
previously as we didn't check for that in parse_arg either.... this is fine as
is I suppose - can be addressed separately if need be.
> }
>
> /*
> @@ -975,15 +964,17 @@ static ssize_t ledd_store(struct device *dev, struct device_attribute *attr,
> struct asus_laptop *asus = dev_get_drvdata(dev);
> int rv, value;
>
> - rv = parse_arg(buf, count, &value);
> - if (rv > 0) {
> - if (write_acpi_int(asus->handle, METHOD_LEDD, value)) {
> - pr_warn("LED display write failed\n");
> - return -ENODEV;
> - }
> - asus->ledd_status = (u32) value;
> + rv = kstrtoint(buf, 0, &value);
> + if (rv < 0)
> + return rv;
>
This inverts the check to check for failure (this is preferred), but it does
change the successful path to include the value of 0, which was skipped over in
the original above.
> + if (write_acpi_int(asus->handle, METHOD_LEDD, value)) {
What is value if rv is 0? Perhaps safer/more explicit to test for (rv <= 0)
above. Please consider, and apply decision to all similar instances below.
> + pr_warn("LED display write failed\n");
> + return -ENODEV;
> }
> - return rv;
> +
> + asus->ledd_status = (u32) value;
> + return count;
> }
> static DEVICE_ATTR_RW(ledd);
>
> @@ -1148,10 +1139,12 @@ static ssize_t display_store(struct device *dev, struct device_attribute *attr,
> struct asus_laptop *asus = dev_get_drvdata(dev);
> int rv, value;
>
> - rv = parse_arg(buf, count, &value);
> - if (rv > 0)
> - asus_set_display(asus, value);
> - return rv;
> + rv = kstrtoint(buf, 0, &value);
> + if (rv < 0)
> + return rv;
> +
> + asus_set_display(asus, value);
> + return count;
> }
> static DEVICE_ATTR_WO(display);
>
> @@ -1190,11 +1183,12 @@ static ssize_t ls_switch_store(struct device *dev,
> struct asus_laptop *asus = dev_get_drvdata(dev);
> int rv, value;
>
> - rv = parse_arg(buf, count, &value);
> - if (rv > 0)
> - asus_als_switch(asus, value ? 1 : 0);
> + rv = kstrtoint(buf, 0, &value);
> + if (rv < 0)
> + return rv;
>
> - return rv;
> + asus_als_switch(asus, value ? 1 : 0);
> + return count;
> }
> static DEVICE_ATTR_RW(ls_switch);
>
> @@ -1219,14 +1213,15 @@ static ssize_t ls_level_store(struct device *dev, struct device_attribute *attr,
> struct asus_laptop *asus = dev_get_drvdata(dev);
> int rv, value;
>
> - rv = parse_arg(buf, count, &value);
> - if (rv > 0) {
> - value = (0 < value) ? ((15 < value) ? 15 : value) : 0;
> - /* 0 <= value <= 15 */
> - asus_als_level(asus, value);
> - }
> + rv = kstrtoint(buf, 0, &value);
> + if (rv < 0)
> + return rv;
> +
> + value = (0 < value) ? ((15 < value) ? 15 : value) : 0;
> + /* 0 <= value <= 15 */
> + asus_als_level(asus, value);
>
> - return rv;
> + return count;
> }
> static DEVICE_ATTR_RW(ls_level);
>
> @@ -1301,14 +1296,14 @@ static ssize_t gps_store(struct device *dev, struct device_attribute *attr,
> int rv, value;
> int ret;
>
> - rv = parse_arg(buf, count, &value);
> - if (rv <= 0)
> - return -EINVAL;
> + rv = kstrtoint(buf, 0, &value);
> + if (rv < 0)
> + return rv;
> ret = asus_gps_switch(asus, !!value);
> if (ret)
> return ret;
> rfkill_set_sw_state(asus->gps.rfkill, !value);
> - return rv;
> + return count;
> }
> static DEVICE_ATTR_RW(gps);
>
> --
> 2.9.0
>
>
--
Darren Hart
Intel Open Source Technology Center
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