// SPDX-License-Identifier: GPL-2.0-or-later/* delayacct.c - per-task delay accounting * * Copyright (C) Shailabh Nagar, IBM Corp. 2006 */ #include <linux/sched.h>#include <linux/sched/task.h>#include <linux/sched/cputime.h>#include <linux/sched/clock.h>#include <linux/slab.h>#include <linux/taskstats.h>#include <linux/sysctl.h>#include <linux/delayacct.h>#include <linux/module.h> DEFINE_STATIC_KEY_FALSE(delayacct_key);int delayacct_on __read_mostly;	/* Delay accounting turned on/off */struct kmem_cache *delayacct_cache; static void set_delayacct(bool enabled){	if (enabled) {		static_branch_enable(&delayacct_key);		delayacct_on = 1;	} else {		delayacct_on = 0;		static_branch_disable(&delayacct_key);	}} static int __init delayacct_setup_enable(char *str){	delayacct_on = 1;	return 1;}__setup("delayacct", delayacct_setup_enable); void delayacct_init(void){	delayacct_cache = KMEM_CACHE(task_delay_info, SLAB_PANIC|SLAB_ACCOUNT);	delayacct_tsk_init(&init_task);	set_delayacct(delayacct_on);} #ifdef CONFIG_PROC_SYSCTLint sysctl_delayacct(struct ctl_table *table, int write, void *buffer,		     size_t *lenp, loff_t *ppos){	int state = delayacct_on;	struct ctl_table t;	int err; 	if (write && !capable(CAP_SYS_ADMIN))		return -EPERM; 	t = *table;	t.data = &state;	err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);	if (err < 0)		return err;	if (write)		set_delayacct(state);	return err;}#endif void __delayacct_tsk_init(struct task_struct *tsk){	tsk->delays = kmem_cache_zalloc(delayacct_cache, GFP_KERNEL);	if (tsk->delays)		raw_spin_lock_init(&tsk->delays->lock);} /* * Finish delay accounting for a statistic using its timestamps (@start), * accumalator (@total) and @count */static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count){	s64 ns = local_clock() - *start;	unsigned long flags; 	if (ns > 0) {		raw_spin_lock_irqsave(lock, flags);		*total += ns;		(*count)++;		raw_spin_unlock_irqrestore(lock, flags);	}} void __delayacct_blkio_start(void){	current->delays->blkio_start = local_clock();} /* * We cannot rely on the `current` macro, as we haven't yet switched back to * the process being woken. */void __delayacct_blkio_end(struct task_struct *p){	delayacct_end(&p->delays->lock,		      &p->delays->blkio_start,		      &p->delays->blkio_delay,		      &p->delays->blkio_count);} int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk){	u64 utime, stime, stimescaled, utimescaled;	unsigned long long t2, t3;	unsigned long flags, t1;	s64 tmp; 	task_cputime(tsk, &utime, &stime);	tmp = (s64)d->cpu_run_real_total;	tmp += utime + stime;	d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp; 	task_cputime_scaled(tsk, &utimescaled, &stimescaled);	tmp = (s64)d->cpu_scaled_run_real_total;	tmp += utimescaled + stimescaled;	d->cpu_scaled_run_real_total =		(tmp < (s64)d->cpu_scaled_run_real_total) ? 0 : tmp; 	/*	 * No locking available for sched_info (and too expensive to add one)	 * Mitigate by taking snapshot of values	 */	t1 = tsk->sched_info.pcount;	t2 = tsk->sched_info.run_delay;	t3 = tsk->se.sum_exec_runtime; 	d->cpu_count += t1; 	tmp = (s64)d->cpu_delay_total + t2;	d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp; 	tmp = (s64)d->cpu_run_virtual_total + t3;	d->cpu_run_virtual_total =		(tmp < (s64)d->cpu_run_virtual_total) ?	0 : tmp; 	if (!tsk->delays)		return 0; 	/* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */ 	raw_spin_lock_irqsave(&tsk->delays->lock, flags);	tmp = d->blkio_delay_total + tsk->delays->blkio_delay;	d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;	tmp = d->swapin_delay_total + tsk->delays->swapin_delay;	d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;	tmp = d->freepages_delay_total + tsk->delays->freepages_delay;	d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;	tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay;	d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp;	tmp = d->compact_delay_total + tsk->delays->compact_delay;	d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp;	d->blkio_count += tsk->delays->blkio_count;	d->swapin_count += tsk->delays->swapin_count;	d->freepages_count += tsk->delays->freepages_count;	d->thrashing_count += tsk->delays->thrashing_count;	d->compact_count += tsk->delays->compact_count;	raw_spin_unlock_irqrestore(&tsk->delays->lock, flags); 	return 0;} __u64 __delayacct_blkio_ticks(struct task_struct *tsk){	__u64 ret;	unsigned long flags; 	raw_spin_lock_irqsave(&tsk->delays->lock, flags);	ret = nsec_to_clock_t(tsk->delays->blkio_delay);	raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);	return ret;} void __delayacct_freepages_start(void){	current->delays->freepages_start = local_clock();} void __delayacct_freepages_end(void){	delayacct_end(&current->delays->lock,		      &current->delays->freepages_start,		      &current->delays->freepages_delay,		      &current->delays->freepages_count);} void __delayacct_thrashing_start(void){	current->delays->thrashing_start = local_clock();} void __delayacct_thrashing_end(void){	delayacct_end(&current->delays->lock,		      &current->delays->thrashing_start,		      &current->delays->thrashing_delay,		      &current->delays->thrashing_count);} void __delayacct_swapin_start(void){	current->delays->swapin_start = local_clock();} void __delayacct_swapin_end(void){	delayacct_end(&current->delays->lock,		      &current->delays->swapin_start,		      &current->delays->swapin_delay,		      &current->delays->swapin_count);} void __delayacct_compact_start(void){	current->delays->compact_start = local_clock();} void __delayacct_compact_end(void){	delayacct_end(&current->delays->lock,		      &current->delays->compact_start,		      &current->delays->compact_delay,		      &current->delays->compact_count);}