Messages in this thread Patch in this message | | | From | Henrik Austad <> | Subject | [PATCH 6/6] Expose tick_set_forced_cpu() via sysfs | Date | Tue, 25 Feb 2014 13:34:01 +0100 |
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From: Henrik Austad <haustad@cisco.com>
This allows userspace to set the forced CPU via sysfs in /sys/kernel/timekeeping/forced_cpu.
CC: Thomas Gleixner <tglx@linutronix.de> CC: Peter Zijlstra <peterz@infradead.org> CC: Frederic Weisbecker <fweisbec@gmail.com> CC: John Stultz <john.stultz@linaro.org> CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Henrik Austad <haustad@cisco.com> --- kernel/time/timekeeping.c | 36 ++++++++++++++++++++++++++++++------ 1 file changed, 30 insertions(+), 6 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 4bdfa11..b148062 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -44,23 +44,47 @@ int expose_tick_forced_timer_cpu = -1; /* * sysfs interface to timer-cpu */ -static ssize_t current_cpu_show(struct kobject *kobj, - struct kobj_attribute *attr, - char *buf) -{ - return sprintf(buf, "%d\n", tick_expose_cpu()); +static ssize_t cpu_show(struct kobject *kobj, + struct kobj_attribute *attr, + char *buf) +{ + int var = -EINVAL; + if (strcmp(attr->attr.name, "current_cpu") == 0) + var = sprintf(buf, "%d\n", tick_expose_cpu()); + else if (strcmp(attr->attr.name, "forced_cpu") == 0) + var = sprintf(buf, "%d\n", tick_get_forced_cpu()); + return var; +} + +static ssize_t cpu_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char * buf, + size_t count) +{ + int var = 0; + if (strcmp(attr->attr.name, "forced_cpu") == 0) { + sscanf(buf, "%du", &var); + if ((var = tick_set_forced_cpu(var)) != 0) { + pr_err("trouble setting forced CPU (%d)\n", var); + } + } + return count; } static struct kobj_attribute current_cpu_attribute = - __ATTR_RO(current_cpu); + __ATTR(current_cpu, 0444, cpu_show, NULL); +static struct kobj_attribute forced_cpu_attribute = + __ATTR(forced_cpu, 0644, cpu_show, cpu_store); static struct attribute *timekeeping_attrs[] = { ¤t_cpu_attribute.attr, + &forced_cpu_attribute.attr, NULL, }; static struct attribute_group timekeeping_ag = { .attrs = timekeeping_attrs, }; + static struct kobject *timekeeping_kobj; static __init int timekeeping_sysfs_init(void) -- 1.7.9.5
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