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authorMikulas Patocka <mpatocka@redhat.com>2014-01-24 16:41:36 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-22 13:34:59 -0800
commit54c028419db7716c0a2bff9cbf438067609db6e5 (patch)
treefdc73b17e174ecda15f61c3c7993f7dc092cb285
parent160e9e9caed114b965d29231c93b96452479e599 (diff)
time: Fix overflow when HZ is smaller than 60
commit 80d767d770fd9c697e434fd080c2db7b5c60c6dd upstream. 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 Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--kernel/time/jiffies.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
index 7a925ba456fb..a6a5bf53e86d 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
+#else
#define JIFFIES_SHIFT 8
+#endif
static cycle_t jiffies_read(struct clocksource *cs)
{