On 64-bit platforms, reads/writes of the various cpustat fields are atomic due to native 64-bit loads/stores. However, on non 64-bit platforms, reads/writes of the cpustat fields are not atomic and could lead to inconsistent statistics.
This problem was originally reported by Frederic Weisbecker as a 64-bit limitation with the nsec granularity cputime accounting for full dynticks, but then we realized that it's a problem that's been around for awhile and not specific to the new cputime accounting. This series fixes this by first converting all access to the cputime fields to use accessor functions, and then converting the accessor functions to use the atomic64 functions. Implemented based on idea proposed by Frederic Weisbecker. Kevin Hilman (2): cpustat: use accessor functions for get/set/add cpustat: convert to atomic operations arch/s390/appldata/appldata_os.c | 16 +++++++-------- drivers/cpufreq/cpufreq_governor.c | 18 ++++++++--------- drivers/cpufreq/cpufreq_ondemand.c | 2 +- drivers/macintosh/rack-meter.c | 6 +++--- fs/proc/stat.c | 40 +++++++++++++++++++------------------- fs/proc/uptime.c | 2 +- include/linux/kernel_stat.h | 11 ++++++++++- kernel/sched/core.c | 12 +++++------- kernel/sched/cputime.c | 29 +++++++++++++-------------- 9 files changed, 70 insertions(+), 66 deletions(-) -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
