fs/proc/uptime.c

Source file repositories/reference/linux-study-clean/fs/proc/uptime.c

File Facts

System
Linux kernel
Corpus path
fs/proc/uptime.c
Extension
.c
Size
1072 bytes
Lines
46
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/time.h>
#include <linux/time_namespace.h>
#include <linux/kernel_stat.h>
#include "internal.h"

static int uptime_proc_show(struct seq_file *m, void *v)
{
	struct timespec64 uptime;
	struct timespec64 idle;
	u64 idle_nsec;
	u32 rem;
	int i;

	idle_nsec = 0;
	for_each_possible_cpu(i)
		idle_nsec += kcpustat_field(CPUTIME_IDLE, i);

	ktime_get_boottime_ts64(&uptime);
	timens_add_boottime(&uptime);

	idle.tv_sec = div_u64_rem(idle_nsec, NSEC_PER_SEC, &rem);
	idle.tv_nsec = rem;
	seq_printf(m, "%lu.%02lu %lu.%02lu\n",
			(unsigned long) uptime.tv_sec,
			(uptime.tv_nsec / (NSEC_PER_SEC / 100)),
			(unsigned long) idle.tv_sec,
			(idle.tv_nsec / (NSEC_PER_SEC / 100)));
	return 0;
}

static int __init proc_uptime_init(void)
{
	struct proc_dir_entry *pde;

	pde = proc_create_single("uptime", 0, NULL, uptime_proc_show);
	pde_make_permanent(pde);
	return 0;
}
fs_initcall(proc_uptime_init);

Annotation

Implementation Notes