[PATCH] APM patch: apm_cpu_idle cleanups

Number 7.

This patch contains four cleanup changes whose aim
is better code self-documentation (the best way to
document IMHO).  They are sent together because they
overlap.

1. Rename the variable "sys_idle" to 'original_pm_idle'.
This is where we store the value that we find in pm_idle before
we substitute the address of our own apm_cpu_idle() function.
In principle we have no idea whose address this is, so
the variable name shouldn't imply that we know that this is
the address of a system idle function; it should simply
indicate that it is the original value of pm_idle.

2. Variable "apm_is_idle" is renamed 'apm_idle_done'.
This flag indicates when apm_do_idle() has been called.
It is a premise of apm_cpu_idle()'s operation that it is
not known whether the apm_do_idle() function really idles
the CPU.  The name of the flag should not lead one to
believe otherwise.

3. Variable "t1" is renamed 'bucket'.  The variable is not
a time but a countdown ("bucket"), so the variable name
should not lead one to believe it is some sort of time
value.

4. A default: case is added to the switch in order to
remind the reader that there is a third possible return
value from apm_do_idle().

diff --git a/arch/i386/kernel/apm.c b/arch/i386/kernel/apm.c
index 415bcc083cb98ab0995cfe211e0c5c5e3a81204b..c20530fdec65101c9662c1a358060eb46fc967b7 100644 (file)
--- a/arch/i386/kernel/apm.c
+++ b/arch/i386/kernel/apm.c
@@ -788,7 +788,7 @@ static void apm_do_busy(void)
 #define IDLE_CALC_LIMIT   (HZ * 100)
 #define IDLE_LEAKY_MAX    16
 
-static void (*sys_idle)(void);
+static void (*original_pm_idle)(void);
 
 extern void default_idle(void);
 
@@ -806,10 +806,9 @@ static void apm_cpu_idle(void)
        static unsigned int last_jiffies; /* = 0 */
        static unsigned int last_stime; /* = 0 */
 
-       int apm_is_idle = 0;
+       int apm_idle_done = 0;
        unsigned int jiffies_since_last_check = jiffies - last_jiffies;
-       unsigned int t1;
-
+       unsigned int bucket;
 
 recalc:
        if (jiffies_since_last_check > IDLE_CALC_LIMIT) {
@@ -827,7 +826,7 @@ recalc:
                last_stime = current->times.tms_stime;
        }
 
-       t1 = IDLE_LEAKY_MAX;
+       bucket = IDLE_LEAKY_MAX;
 
        while (!need_resched()) {
                if (use_apm_idle) {
@@ -835,23 +834,24 @@ recalc:
 
                        t = jiffies;
                        switch (apm_do_idle()) {
-                       case 0: apm_is_idle = 1;
+                       case 0: apm_idle_done = 1;
                                if (t != jiffies) {
-                                       if (t1) {
-                                               t1 = IDLE_LEAKY_MAX;
+                                       if (bucket) {
+                                               bucket = IDLE_LEAKY_MAX;
                                                continue;
                                        }
-                               } else if (t1) {
-                                       t1--;
+                               } else if (bucket) {
+                                       bucket--;
                                        continue;
                                }
                                break;
-                       case 1: apm_is_idle = 1;
+                       case 1: apm_idle_done = 1;
                                break;
+                       default: /* BIOS refused */
                        }
                }
-               if (sys_idle)
-                       sys_idle();
+               if (original_pm_idle)
+                       original_pm_idle();
                else
                        default_idle();
                jiffies_since_last_check = jiffies - last_jiffies;
@@ -859,7 +859,7 @@ recalc:
                        goto recalc;
        }
 
-       if (apm_is_idle)
+       if (apm_idle_done)
                apm_do_busy();
 }
 
@@ -1967,7 +1967,7 @@ static int __init apm_init(void)
        if (HZ != 100)
                idle_period = (idle_period * HZ) / 100;
        if (idle_threshold < 100) {
-               sys_idle = pm_idle;
+               original_pm_idle = pm_idle;
                pm_idle  = apm_cpu_idle;
                set_pm_idle = 1;
        }
@@ -1980,7 +1980,7 @@ static void __exit apm_exit(void)
        int     error;
 
        if (set_pm_idle)
-               pm_idle = sys_idle;
+               pm_idle = original_pm_idle;
        if (((apm_info.bios.flags & APM_BIOS_DISENGAGED) == 0)
            && (apm_info.connection_version > 0x0100)) {
                error = apm_engage_power_management(APM_DEVICE_ALL, 0);