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authorJohn Stultz <john.stultz@linaro.org>2015-03-12 07:16:31 +0300
committerIngo Molnar <mingo@kernel.org>2015-03-12 12:16:38 +0300
commitfb82fe2fe8588745edd73aa3a6229facac5c1e15 (patch)
tree1ab7c25dfa0e89f83f07fad2a04467d8c7864ebb /include/linux/clocksource.h
parent362fde0410377e468ca00ad363fdf3e3ec42eb6a (diff)
downloadlinux-fb82fe2fe8588745edd73aa3a6229facac5c1e15.tar.xz
clocksource: Add 'max_cycles' to 'struct clocksource'
In order to facilitate clocksource validation, add a 'max_cycles' field to the clocksource structure which will hold the maximum cycle value that can safely be multiplied without potentially causing an overflow. Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Dave Jones <davej@codemonkey.org.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Stephen Boyd <sboyd@codeaurora.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1426133800-29329-4-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/clocksource.h')
-rw-r--r--include/linux/clocksource.h5
1 files changed, 3 insertions, 2 deletions
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 9c78d15d33e4..16d048cadebb 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -56,6 +56,7 @@ struct module;
* @shift: cycle to nanosecond divisor (power of two)
* @max_idle_ns: max idle time permitted by the clocksource (nsecs)
* @maxadj: maximum adjustment value to mult (~11%)
+ * @max_cycles: maximum safe cycle value which won't overflow on multiplication
* @flags: flags describing special properties
* @archdata: arch-specific data
* @suspend: suspend function for the clocksource, if necessary
@@ -76,7 +77,7 @@ struct clocksource {
#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
struct arch_clocksource_data archdata;
#endif
-
+ u64 max_cycles;
const char *name;
struct list_head list;
int rating;
@@ -189,7 +190,7 @@ extern struct clocksource * __init clocksource_default_clock(void);
extern void clocksource_mark_unstable(struct clocksource *cs);
extern u64
-clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask);
+clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles);
extern void
clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);