timer_list-convert-timer-list-to-be-a-proper-seq_file-v2

v2: Added comments on the iteration.

Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index c438d759228d243f7b1d4df09d6483375c91bf1b..1098ee4d23c879925a80722f6f9398c79753adba 100644 (file)
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -274,6 +274,19 @@ static int timer_list_show(struct seq_file *m, void *v)
        return 0;
 }
 
+/*
+ * This itererator really needs some explination since it is offset and has
+ * two passes one of which is controlled by a config option.
+ * In a hotplugged system some cpus, including cpu 0, may be missing so we have
+ * to use cpumask_* to iterate over the cpus.
+ * For the first pass:
+ * It returns 1 for the header position.
+ * For cpu 0 it returns 2 and the final possible cpu would be nr_cpu_ids + 1.
+ * On the second pass:
+ * It returnes nr_cpu_ids + 1 for the second header position.
+ * For cpu 0 it returns nr_cpu_ids + 2
+ * The final possible cpu would be nr_cpu_ids + nr_cpu_ids + 2.
+ */
 static void *timer_list_start(struct seq_file *file, loff_t *offset)
 {
        unsigned long n = *offset;