[PATCH] fork: total_forks not counted under tasklist_lock

Bring the total_forks under tasklist_lock.  When most of the fork code
icluding nr_threads is moved to copy_process() from do_fork() code in 2.6,
this is left out.

Althought accuracy of total_forks is not important, it would be nice to add
this.  It does not involve additional cost, and the code will be cleaner if
it is grouped with nr_threads.  The difference is, total_forks will
increase on fork, but nr_threads will increase on fork and decrease on the
exit.

I also moved extern decleration to sched.h from proc_misc.c.
Signed-off-by: Prasanna Meda <pmeda@akamai.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/proc/proc_misc.c

@@ -322,7 +322,6 @@ static struct file_operations proc_slabinfo_operations = {
 int show_stat(struct seq_file *p, void *v)
 {
 	int i;
-	extern unsigned long total_forks;
 	unsigned long jif;
 	u64	sum = 0, user = 0, nice = 0, system = 0,
 		idle = 0, iowait = 0, irq = 0, softirq = 0;

include/linux/sched.h

@@ -88,6 +88,7 @@ extern unsigned long avenrun[];		/* Load averages */
 #define CT_TO_SECS(x)	((x) / HZ)
 #define CT_TO_USECS(x)	(((x) % HZ) * 1000000/HZ)
 
+extern unsigned long total_forks;
 extern int nr_threads;
 extern int last_pid;
 DECLARE_PER_CPU(unsigned long, process_counts);

kernel/fork.c

@@ -48,13 +48,13 @@
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 
-/* The idle threads do not count..
- * Protected by write_lock_irq(&tasklist_lock)
+/*
+ * Protected counters by write_lock_irq(&tasklist_lock)
  */
-int nr_threads;
-
-int max_threads;
 unsigned long total_forks;	/* Handle normal Linux uptimes. */
+int nr_threads; 		/* The idle threads do not count.. */
+
+int max_threads;		/* tunable limit on nr_threads */
 
 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
 
@@ -1035,6 +1035,7 @@ static task_t *copy_process(unsigned long clone_flags,
 	}
 
 	nr_threads++;
+	total_forks++;
 	write_unlock_irq(&tasklist_lock);
 	retval = 0;
 
@@ -1167,7 +1168,6 @@ long do_fork(unsigned long clone_flags,
 			wake_up_new_task(p, clone_flags);
 		else
 			p->state = TASK_STOPPED;
-		++total_forks;
 
 		if (unlikely (trace)) {
 			current->ptrace_message = pid;