[S390] fix cputime overflow in uptime_proc_show

For 32-bit architectures using standard jiffies the idletime calculation in uptime_proc_show will quickly overflow. It takes (2^32 / HZ) seconds of idle-time, or e.g. 12.45 days with no load on a quad-core with HZ=1000. Switch to 64-bit calculations. Cc: [email protected] Cc: Michael Abbott <[email protected]> Signed-off-by: Martin Schwidefsky <[email protected]>
josf · Dec 15, 2011 · c3e0ef9 · c3e0ef9
1 parent 6486163
commit c3e0ef9
Showing 1 changed file with 7 additions and 2 deletions.
diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
@@ -11,15 +11,20 @@ static int uptime_proc_show(struct seq_file *m, void *v)
 {
 	struct timespec uptime;
 	struct timespec idle;
+	cputime64_t idletime;
+	u64 nsec;
+	u32 rem;
 	int i;
-	cputime_t idletime = 0;
 
+	idletime = 0;
 	for_each_possible_cpu(i)
 		idletime += kstat_cpu(i).cpustat.idle;
 
 	do_posix_clock_monotonic_gettime(&uptime);
 	monotonic_to_bootbased(&uptime);
-	cputime_to_timespec(idletime, &idle);
+	nsec = cputime64_to_jiffies64(idletime) * TICK_NSEC;
+	idle.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
+	idle.tv_nsec = rem;
 	seq_printf(m, "%lu.%02lu %lu.%02lu\n",
 			(unsigned long) uptime.tv_sec,
 			(uptime.tv_nsec / (NSEC_PER_SEC / 100)),