From: Kirill A. Shutemov <[email protected]> Process can change its timer slack using prctl(). Timer slack notifier call chain allows to react on such change or forbid it.
Signed-off-by: Kirill A. Shutemov <[email protected]> --- include/linux/sched.h | 5 ++++ kernel/Makefile | 2 +- kernel/sys.c | 9 +------ kernel/timer_slack.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 65 insertions(+), 8 deletions(-) create mode 100644 kernel/timer_slack.c diff --git a/include/linux/sched.h b/include/linux/sched.h index d747f94..f1a4ec2 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2620,6 +2620,11 @@ static inline unsigned long rlimit_max(unsigned int limit) return task_rlimit_max(current, limit); } +extern int register_timer_slack_notifier(struct notifier_block *nb); +extern void unregister_timer_slack_notifier(struct notifier_block *nb); +long prctl_get_timer_slack(void); +extern long prctl_set_timer_slack(long timer_slack_ns); + #endif /* __KERNEL__ */ #endif diff --git a/kernel/Makefile b/kernel/Makefile index 353d3fe..aa43e63 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -10,7 +10,7 @@ obj-y = sched.o fork.o exec_domain.o panic.o printk.o \ kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \ hrtimer.o rwsem.o nsproxy.o srcu.o semaphore.o \ notifier.o ksysfs.o pm_qos_params.o sched_clock.o cred.o \ - async.o range.o jump_label.o + async.o range.o jump_label.o timer_slack.o obj-y += groups.o ifdef CONFIG_FUNCTION_TRACER diff --git a/kernel/sys.c b/kernel/sys.c index 18da702..a33e4b8 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1691,15 +1691,10 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, error = perf_event_task_enable(); break; case PR_GET_TIMERSLACK: - error = current->timer_slack_ns; + error = prctl_get_timer_slack(); break; case PR_SET_TIMERSLACK: - if (arg2 <= 0) - current->timer_slack_ns = - current->default_timer_slack_ns; - else - current->timer_slack_ns = arg2; - error = 0; + error = prctl_set_timer_slack(arg2); break; case PR_MCE_KILL: if (arg4 | arg5) diff --git a/kernel/timer_slack.c b/kernel/timer_slack.c new file mode 100644 index 0000000..546ed78 --- /dev/null +++ b/kernel/timer_slack.c @@ -0,0 +1,57 @@ +/* + * kernel/timer_slack.c + * + * Copyright Nokia Corparation, 2011 + * Author: Kirill A. Shutemov + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/notifier.h> +#include <linux/module.h> +#include <linux/sched.h> + +static BLOCKING_NOTIFIER_HEAD(timer_slack_notify_list); + +int register_timer_slack_notifier(struct notifier_block *nb) +{ + return blocking_notifier_chain_register(&timer_slack_notify_list, nb); +} +EXPORT_SYMBOL_GPL(register_timer_slack_notifier); + +void unregister_timer_slack_notifier(struct notifier_block *nb) +{ + blocking_notifier_chain_unregister(&timer_slack_notify_list, nb); +} +EXPORT_SYMBOL_GPL(unregister_timer_slack_notifier); + +long prctl_get_timer_slack(void) +{ + return current->timer_slack_ns; +} + +long prctl_set_timer_slack(long timer_slack_ns) +{ + int err; + + /* Reset timer slack to default value */ + if (timer_slack_ns <= 0) { + current->timer_slack_ns = current->default_timer_slack_ns; + return 0; + } + + err = blocking_notifier_call_chain(&timer_slack_notify_list, + timer_slack_ns, NULL); + if (err == NOTIFY_DONE) + current->timer_slack_ns = timer_slack_ns; + + return notifier_to_errno(err); +} -- 1.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
