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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 12:41:29 -0800
commitea7dfc423c1a4a33232f99c401fda77129619289 (patch)
tree69f4ed00c7c5ce8c2ded9875772554f899bf7b37
parent4d4ef86d4438e741960a9c9b615b2fb3e7c2f779 (diff)
downloadlinux-ea7dfc423c1a4a33232f99c401fda77129619289.tar.gz
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 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
+#else
#define JIFFIES_SHIFT 8
+#endif
static cycle_t jiffies_read(struct clocksource *cs)
{