s390 uses open coded seqcount to synchronize idle time accounting. Lets consolidate it with the standard API.
Cc: Benjamin Herrenschmidt <[email protected]> Cc: Heiko Carstens <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Martin Schwidefsky <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Tony Luck <[email protected]> Cc: Wu Fengguang <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]> --- arch/s390/include/asm/idle.h | 3 ++- arch/s390/kernel/idle.c | 28 +++++++++++++++------------- 2 files changed, 17 insertions(+), 14 deletions(-) diff --git a/arch/s390/include/asm/idle.h b/arch/s390/include/asm/idle.h index 6af037f..113cd96 100644 --- a/arch/s390/include/asm/idle.h +++ b/arch/s390/include/asm/idle.h @@ -9,9 +9,10 @@ #include <linux/types.h> #include <linux/device.h> +#include <linux/seqlock.h> struct s390_idle_data { - unsigned int sequence; + seqcount_t seqcount; unsigned long long idle_count; unsigned long long idle_time; unsigned long long clock_idle_enter; diff --git a/arch/s390/kernel/idle.c b/arch/s390/kernel/idle.c index 7559f1b..9b75577 100644 --- a/arch/s390/kernel/idle.c +++ b/arch/s390/kernel/idle.c @@ -36,15 +36,13 @@ void __kprobes enabled_wait(void) psw_idle(idle, psw_mask); /* Account time spent with enabled wait psw loaded as idle time. */ - idle->sequence++; - smp_wmb(); + write_seqcount_begin(&idle->seqcount); idle_time = idle->clock_idle_exit - idle->clock_idle_enter; idle->clock_idle_enter = idle->clock_idle_exit = 0ULL; idle->idle_time += idle_time; idle->idle_count++; account_idle_time(idle_time); - smp_wmb(); - idle->sequence++; + write_seqcount_end(&idle->seqcount); } static ssize_t show_idle_count(struct device *dev, @@ -52,14 +50,15 @@ static ssize_t show_idle_count(struct device *dev, { struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id); unsigned long long idle_count; - unsigned int sequence; + unsigned int seq; do { - sequence = ACCESS_ONCE(idle->sequence); + seq = read_seqcount_begin(&idle->seqcount); idle_count = ACCESS_ONCE(idle->idle_count); if (ACCESS_ONCE(idle->clock_idle_enter)) idle_count++; - } while ((sequence & 1) || (ACCESS_ONCE(idle->sequence) != sequence)); + } while (read_seqcount_retry(&idle->seqcount, seq)); + return sprintf(buf, "%llu\n", idle_count); } DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL); @@ -69,16 +68,18 @@ static ssize_t show_idle_time(struct device *dev, { struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id); unsigned long long now, idle_time, idle_enter, idle_exit; - unsigned int sequence; + unsigned int seq; do { now = get_tod_clock(); - sequence = ACCESS_ONCE(idle->sequence); + seq = read_seqcount_begin(&idle->seqcount); idle_time = ACCESS_ONCE(idle->idle_time); idle_enter = ACCESS_ONCE(idle->clock_idle_enter); idle_exit = ACCESS_ONCE(idle->clock_idle_exit); - } while ((sequence & 1) || (ACCESS_ONCE(idle->sequence) != sequence)); + } while (read_seqcount_retry(&idle->seqcount, seq)); + idle_time += idle_enter ? ((idle_exit ? : now) - idle_enter) : 0; + return sprintf(buf, "%llu\n", idle_time >> 12); } DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL); @@ -87,14 +88,15 @@ cputime64_t arch_cpu_idle_time(int cpu) { struct s390_idle_data *idle = &per_cpu(s390_idle, cpu); unsigned long long now, idle_enter, idle_exit; - unsigned int sequence; + unsigned int seq; do { now = get_tod_clock(); - sequence = ACCESS_ONCE(idle->sequence); + seq = read_seqcount_begin(&idle->seqcount); idle_enter = ACCESS_ONCE(idle->clock_idle_enter); idle_exit = ACCESS_ONCE(idle->clock_idle_exit); - } while ((sequence & 1) || (ACCESS_ONCE(idle->sequence) != sequence)); + } while (read_seqcount_retry(&idle->seqcount, seq)); + return idle_enter ? ((idle_exit ?: now) - idle_enter) : 0; } -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
