Commit 19298fbf authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

posix-cpu-timers: Provide quick sample function for itimer 



get_itimer() needs a sample of the current thread group cputime. It invokes
thread_group_cputimer() - which is a misnomer. That function also starts
eventually the group cputime accouting which is bogus because the
accounting is already active when a timer is armed.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20190821192919.599658199@linutronix.de
parent e5a8b65b

include/linux/sched/cputime.h

+1 −1
Original line number Diff line number Diff line
@@ -62,7 +62,7 @@ extern void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev, 
 */

void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times);

void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times);



void thread_group_sample_cputime(struct task_struct *tsk, struct task_cputime *times);



/*

 * The following are functions that support scheduler-internal time accounting.

kernel/time/posix-cpu-timers.c

+21 −0
Original line number Diff line number Diff line
@@ -232,6 +232,27 @@ static inline void sample_cputime_atomic(struct task_cputime *times, 
	times->sum_exec_runtime = atomic64_read(&atomic_times->sum_exec_runtime);

}



/**

 * thread_group_sample_cputime - Sample cputime for a given task

 * @tsk:	Task for which cputime needs to be started

 * @iimes:	Storage for time samples

 *

 * Called from sys_getitimer() to calculate the expiry time of an active

 * timer. That means group cputime accounting is already active. Called

 * with task sighand lock held.

 *

 * Updates @times with an uptodate sample of the thread group cputimes.

 */

void thread_group_sample_cputime(struct task_struct *tsk,

				struct task_cputime *times)

{

	struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;



	WARN_ON_ONCE(!cputimer->running);



	sample_cputime_atomic(times, &cputimer->cputime_atomic);

}



void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)

{

	struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;

CRA Git | Maintained and supported by SUSTech CRA and CCSE