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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
parent38dbfb59d1175ef458d006556061adeaa8751b72 (diff)
downloadop-kernel-dev-80d767d770fd9c697e434fd080c2db7b5c60c6dd.zip
op-kernel-dev-80d767d770fd9c697e434fd080c2db7b5c60c6dd.tar.gz
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>
-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 7a925ba..a6a5bf5 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)
{
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