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| author | John Stultz <john.stultz@linaro.org> | 2015-03-11 21:16:31 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-03-12 10:16:38 +0100 |
| commit | fb82fe2fe8588745edd73aa3a6229facac5c1e15 (patch) | |
| tree | 1ab7c25dfa0e89f83f07fad2a04467d8c7864ebb /include/linux/clocksource.h | |
| parent | 362fde0410377e468ca00ad363fdf3e3ec42eb6a (diff) | |
| download | lwn-fb82fe2fe8588745edd73aa3a6229facac5c1e15.tar.gz lwn-fb82fe2fe8588745edd73aa3a6229facac5c1e15.zip | |
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.h | 5 |
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); |