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authorJon Hunter <jon-hunter@ti.com>2009-08-18 12:45:10 -0500
committerThomas Gleixner <tglx@linutronix.de>2009-11-13 20:46:24 +0100
commit98962465ed9e6ea99c38e0af63fe1dcb5a79dc25 (patch)
treef3f69ad8f6cd47e72a75da6de49eb3402f15cd9b /include/linux/clocksource.h
parent529eaccd900a59724619b4a6ef6579fd518d5218 (diff)
nohz: Prevent clocksource wrapping during idle
The dynamic tick allows the kernel to sleep for periods longer than a single tick, but it does not limit the sleep time currently. In the worst case the kernel could sleep longer than the wrap around time of the time keeping clock source which would result in losing track of time. Prevent this by limiting it to the safe maximum sleep time of the current time keeping clock source. The value is calculated when the clock source is registered. [ tglx: simplified the code a bit and massaged the commit msg ] Signed-off-by: Jon Hunter <jon-hunter@ti.com> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <1250617512-23567-2-git-send-email-jon-hunter@ti.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include/linux/clocksource.h')
-rw-r--r--include/linux/clocksource.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index f57f88250526..279c5478e8a6 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -151,6 +151,7 @@ extern u64 timecounter_cyc2time(struct timecounter *tc,
* subtraction of non 64 bit counters
* @mult: cycle to nanosecond multiplier
* @shift: cycle to nanosecond divisor (power of two)
+ * @max_idle_ns: max idle time permitted by the clocksource (nsecs)
* @flags: flags describing special properties
* @vread: vsyscall based read
* @resume: resume function for the clocksource, if necessary
@@ -168,6 +169,7 @@ struct clocksource {
cycle_t mask;
u32 mult;
u32 shift;
+ u64 max_idle_ns;
unsigned long flags;
cycle_t (*vread)(void);
void (*resume)(void);