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Commit c3e0ef9a authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[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: stable@vger.kernel.org
Cc: Michael Abbott <michael.abbott@diamond.ac.uk>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 64861634

fs/proc/uptime.c

+7 −2
Original line number Diff line number Diff line
@@ -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)),