proc: switch /proc/loadavg to seq_file

and move it to fs/proc/loadavg.c while I'm at it.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/fs/proc/loadavg.c b/fs/proc/loadavg.c
new file mode 100644
index 00000000000..9bca39cf99e
--- /dev/null
+++ b/fs/proc/loadavg.c
@@ -0,0 +1,51 @@
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/pid_namespace.h>
+#include <linux/proc_fs.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+#include <linux/seqlock.h>
+#include <linux/time.h>
+
+#define LOAD_INT(x) ((x) >> FSHIFT)
+#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
+
+static int loadavg_proc_show(struct seq_file *m, void *v)
+{
+	int a, b, c;
+	unsigned long seq;
+
+	do {
+		seq = read_seqbegin(&xtime_lock);
+		a = avenrun[0] + (FIXED_1/200);
+		b = avenrun[1] + (FIXED_1/200);
+		c = avenrun[2] + (FIXED_1/200);
+	} while (read_seqretry(&xtime_lock, seq));
+
+	seq_printf(m, "%d.%02d %d.%02d %d.%02d %ld/%d %d\n",
+		LOAD_INT(a), LOAD_FRAC(a),
+		LOAD_INT(b), LOAD_FRAC(b),
+		LOAD_INT(c), LOAD_FRAC(c),
+		nr_running(), nr_threads,
+		task_active_pid_ns(current)->last_pid);
+	return 0;
+}
+
+static int loadavg_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, loadavg_proc_show, NULL);
+}
+
+static const struct file_operations loadavg_proc_fops = {
+	.open		= loadavg_proc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int __init proc_loadavg_init(void)
+{
+	proc_create("loadavg", 0, NULL, &loadavg_proc_fops);
+	return 0;
+}
+module_init(proc_loadavg_init);