eeepc-laptop: simplify parse_arg()

parse_arg() has three possible return values:
    -EINVAL if sscanf(), in short, fails;
    zero if "count" is zero; and
    "count" in all other cases

But "count" will never be zero. See, parse_arg() is called by the
various store functions. And the callchain of these functions starts
with sysfs_kf_write(). And that function checks for a zero "count". So
we can stop checking for a zero "count", drop the "count" argument
entirely, and transform parse_arg() into a function that returns zero on
success or a negative error. That, in turn, allows to make those store
functions just return "count" on success. The net effect is that the
code becomes a bit easier to understand.

A nice side effect is that this GCC warning is silenced too:
    drivers/platform/x86/eeepc-laptop.c: In function ‘store_sys_acpi’:
    drivers/platform/x86/eeepc-laptop.c:279:10: warning: ‘value’ may be used uninitialized in this function [-Wmaybe-uninitialized]
      int rv, value;

Which is, of course, the reason to have a look at parse_arg().

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>

diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c
index bd533c2..3095d38 100644 (file)
--- a/drivers/platform/x86/eeepc-laptop.c
+++ b/drivers/platform/x86/eeepc-laptop.c
@@ -263,13 +263,11 @@ static int acpi_setter_handle(struct eeepc_laptop *eeepc, int cm,
 /*
  * Sys helpers
  */
-static int parse_arg(const char *buf, unsigned long count, int *val)
+static int parse_arg(const char *buf, int *val)
 {
-       if (!count)
-               return 0;
        if (sscanf(buf, "%i", val) != 1)
                return -EINVAL;
-       return count;
+       return 0;
 }
 
 static ssize_t store_sys_acpi(struct device *dev, int cm,
@@ -278,12 +276,13 @@ static ssize_t store_sys_acpi(struct device *dev, int cm,
        struct eeepc_laptop *eeepc = dev_get_drvdata(dev);
        int rv, value;
 
-       rv = parse_arg(buf, count, &value);
-       if (rv > 0)
-               value = set_acpi(eeepc, cm, value);
-       if (value < 0)
+       rv = parse_arg(buf, &value);
+       if (rv < 0)
+               return rv;
+       rv = set_acpi(eeepc, cm, value);
+       if (rv < 0)
                return -EIO;
-       return rv;
+       return count;
 }
 
 static ssize_t show_sys_acpi(struct device *dev, int cm, char *buf)
@@ -377,13 +376,13 @@ static ssize_t store_cpufv(struct device *dev,
                return -EPERM;
        if (get_cpufv(eeepc, &c))
                return -ENODEV;
-       rv = parse_arg(buf, count, &value);
+       rv = parse_arg(buf, &value);
        if (rv < 0)
                return rv;
-       if (!rv || value < 0 || value >= c.num)
+       if (value < 0 || value >= c.num)
                return -EINVAL;
        set_acpi(eeepc, CM_ASL_CPUFV, value);
-       return rv;
+       return count;
 }
 
 static ssize_t show_cpufv_disabled(struct device *dev,
@@ -402,7 +401,7 @@ static ssize_t store_cpufv_disabled(struct device *dev,
        struct eeepc_laptop *eeepc = dev_get_drvdata(dev);
        int rv, value;
 
-       rv = parse_arg(buf, count, &value);
+       rv = parse_arg(buf, &value);
        if (rv < 0)
                return rv;
 
@@ -412,7 +411,7 @@ static ssize_t store_cpufv_disabled(struct device *dev,
                        pr_warn("cpufv enabled (not officially supported "
                                "on this model)\n");
                eeepc->cpufv_disabled = false;
-               return rv;
+               return count;
        case 1:
                return -EPERM;
        default:
@@ -1042,10 +1041,11 @@ static ssize_t store_sys_hwmon(void (*set)(int), const char *buf, size_t count)
 {
        int rv, value;
 
-       rv = parse_arg(buf, count, &value);
-       if (rv > 0)
-               set(value);
-       return rv;
+       rv = parse_arg(buf, &value);
+       if (rv < 0)
+               return rv;
+       set(value);
+       return count;
 }
 
 static ssize_t show_sys_hwmon(int (*get)(void), char *buf)