path: root/kernel
diff options
authorMikulas Patocka <mpatocka@redhat.com>2014-01-24 16:41:36 -0500
committerThomas Gleixner <tglx@linutronix.de>2014-02-06 16:01:40 +0100
commit80d767d770fd9c697e434fd080c2db7b5c60c6dd (patch)
tree82cd1a6856fd6cc5f931305bb5e8f011d943edd2 /kernel
parent38dbfb59d1175ef458d006556061adeaa8751b72 (diff)
time: Fix overflow when HZ is smaller than 60
When compiling for the IA-64 ski emulator, HZ is set to 32 because the emulation is slow and we don't want to waste too many cycles processing timers. Alpha also has an option to set HZ to 32. This causes integer underflow in kernel/time/jiffies.c: kernel/time/jiffies.c:66:2: warning: large integer implicitly truncated to unsigned type [-Woverflow] .mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */ ^ This patch reduces the JIFFIES_SHIFT value to avoid the overflow. Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1401241639100.23871@file01.intranet.prod.int.rdu2.redhat.com Cc: stable@vger.kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel')
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
index 7a925ba456f..a6a5bf53e86 100644
--- a/kernel/time/jiffies.c
+++ b/kernel/time/jiffies.c
@@ -51,7 +51,13 @@
* HZ shrinks, so values greater than 8 overflow 32bits when
* HZ=100.
+#if HZ < 34
+#define JIFFIES_SHIFT 6
+#elif HZ < 67
+#define JIFFIES_SHIFT 7
static cycle_t jiffies_read(struct clocksource *cs)