Messages in this thread Patch in this message | | | Date | Thu, 6 Feb 2014 07:04:16 -0800 | From | tip-bot for Mikulas Patocka <> | Subject | [tip:timers/urgent] time: Fix overflow when HZ is smaller than 60 |
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Commit-ID: 80d767d770fd9c697e434fd080c2db7b5c60c6dd Gitweb: http://git.kernel.org/tip/80d767d770fd9c697e434fd080c2db7b5c60c6dd Author: Mikulas Patocka <mpatocka@redhat.com> AuthorDate: Fri, 24 Jan 2014 16:41:36 -0500 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Thu, 6 Feb 2014 16:01:40 +0100
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>
--- kernel/time/jiffies.c | 6 ++++++ 1 file changed, 6 insertions(+)
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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