SLOW_WORK: Move slow_work's proc file to debugfs

Move slow_work's debugging proc file to debugfs.

Signed-off-by: David Howells <dhowells@redhat.com>
Requested-and-acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 227 insertions, 0 deletions

diff --git a/kernel/slow-work-debugfs.c b/kernel/slow-work-debugfs.c
new file mode 100644
index 000000000000..e45c43645298
--- /dev/null
+++ b/kernel/slow-work-debugfs.c
@@ -0,0 +1,227 @@
+/* Slow work debugging
+ *
+ * Copyright (C) 2009 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/slow-work.h>
+#include <linux/fs.h>
+#include <linux/time.h>
+#include <linux/seq_file.h>
+#include "slow-work.h"
+
+#define ITERATOR_SHIFT          (BITS_PER_LONG - 4)
+#define ITERATOR_SELECTOR       (0xfUL << ITERATOR_SHIFT)
+#define ITERATOR_COUNTER        (~ITERATOR_SELECTOR)
+
+void slow_work_new_thread_desc(struct slow_work *work, struct seq_file *m)
+{
+        seq_puts(m, "Slow-work: New thread");
+}
+
+/*
+ * Render the time mark field on a work item into a 5-char time with units plus
+ * a space
+ */
+static void slow_work_print_mark(struct seq_file *m, struct slow_work *work)
+{
+        struct timespec now, diff;
+
+        now = CURRENT_TIME;
+        diff = timespec_sub(now, work->mark);
+
+        if (diff.tv_sec < 0)
+                seq_puts(m, "  -ve ");
+        else if (diff.tv_sec == 0 && diff.tv_nsec < 1000)
+                seq_printf(m, "%3luns ", diff.tv_nsec);
+        else if (diff.tv_sec == 0 && diff.tv_nsec < 1000000)
+                seq_printf(m, "%3luus ", diff.tv_nsec / 1000);
+        else if (diff.tv_sec == 0 && diff.tv_nsec < 1000000000)
+                seq_printf(m, "%3lums ", diff.tv_nsec / 1000000);
+        else if (diff.tv_sec <= 1)
+                seq_puts(m, "   1s ");
+        else if (diff.tv_sec < 60)
+                seq_printf(m, "%4lus ", diff.tv_sec);
+        else if (diff.tv_sec < 60 * 60)
+                seq_printf(m, "%4lum ", diff.tv_sec / 60);
+        else if (diff.tv_sec < 60 * 60 * 24)
+                seq_printf(m, "%4luh ", diff.tv_sec / 3600);
+        else
+                seq_puts(m, "exces ");
+}
+
+/*
+ * Describe a slow work item for debugfs
+ */
+static int slow_work_runqueue_show(struct seq_file *m, void *v)
+{
+        struct slow_work *work;
+        struct list_head *p = v;
+        unsigned long id;
+
+        switch ((unsigned long) v) {
+        case 1:
+                seq_puts(m, "THR PID   ITEM ADDR        FL MARK  DESC\n");
+                return 0;
+        case 2:
+                seq_puts(m, "=== ===== ================ == ===== ==========\n");
+                return 0;
+
+        case 3 ... 3 + SLOW_WORK_THREAD_LIMIT - 1:
+                id = (unsigned long) v - 3;
+
+                read_lock(&slow_work_execs_lock);
+                work = slow_work_execs[id];
+                if (work) {
+                        smp_read_barrier_depends();
+
+                        seq_printf(m, "%3lu %5d %16p %2lx ",
+                                   id, slow_work_pids[id], work, work->flags);
+                        slow_work_print_mark(m, work);
+
+                        if (work->ops->desc)
+                                work->ops->desc(work, m);
+                        seq_putc(m, '\n');
+                }
+                read_unlock(&slow_work_execs_lock);
+                return 0;
+
+        default:
+                work = list_entry(p, struct slow_work, link);
+                seq_printf(m, "%3s     - %16p %2lx ",
+                           work->flags & SLOW_WORK_VERY_SLOW ? "vsq" : "sq",
+                           work, work->flags);
+                slow_work_print_mark(m, work);
+
+                if (work->ops->desc)
+                        work->ops->desc(work, m);
+                seq_putc(m, '\n');
+                return 0;
+        }
+}
+
+/*
+ * map the iterator to a work item
+ */
+static void *slow_work_runqueue_index(struct seq_file *m, loff_t *_pos)
+{
+        struct list_head *p;
+        unsigned long count, id;
+
+        switch (*_pos >> ITERATOR_SHIFT) {
+        case 0x0:
+                if (*_pos == 0)
+                        *_pos = 1;
+                if (*_pos < 3)
+                        return (void *)(unsigned long) *_pos;
+                if (*_pos < 3 + SLOW_WORK_THREAD_LIMIT)
+                        for (id = *_pos - 3;
+                             id < SLOW_WORK_THREAD_LIMIT;
+                             id++, (*_pos)++)
+                                if (slow_work_execs[id])
+                                        return (void *)(unsigned long) *_pos;
+                *_pos = 0x1UL << ITERATOR_SHIFT;
+
+        case 0x1:
+                count = *_pos & ITERATOR_COUNTER;
+                list_for_each(p, &slow_work_queue) {
+                        if (count == 0)
+                                return p;
+                        count--;
+                }
+                *_pos = 0x2UL << ITERATOR_SHIFT;
+
+        case 0x2:
+                count = *_pos & ITERATOR_COUNTER;
+                list_for_each(p, &vslow_work_queue) {
+                        if (count == 0)
+                                return p;
+                        count--;
+                }
+                *_pos = 0x3UL << ITERATOR_SHIFT;
+
+        default:
+                return NULL;
+        }
+}
+
+/*
+ * set up the iterator to start reading from the first line
+ */
+static void *slow_work_runqueue_start(struct seq_file *m, loff_t *_pos)
+{
+        spin_lock_irq(&slow_work_queue_lock);
+        return slow_work_runqueue_index(m, _pos);
+}
+
+/*
+ * move to the next line
+ */
+static void *slow_work_runqueue_next(struct seq_file *m, void *v, loff_t *_pos)
+{
+        struct list_head *p = v;
+        unsigned long selector = *_pos >> ITERATOR_SHIFT;
+
+        (*_pos)++;
+        switch (selector) {
+        case 0x0:
+                return slow_work_runqueue_index(m, _pos);
+
+        case 0x1:
+                if (*_pos >> ITERATOR_SHIFT == 0x1) {
+                        p = p->next;
+                        if (p != &slow_work_queue)
+                                return p;
+                }
+                *_pos = 0x2UL << ITERATOR_SHIFT;
+                p = &vslow_work_queue;
+
+        case 0x2:
+                if (*_pos >> ITERATOR_SHIFT == 0x2) {
+                        p = p->next;
+                        if (p != &vslow_work_queue)
+                                return p;
+                }
+                *_pos = 0x3UL << ITERATOR_SHIFT;
+
+        default:
+                return NULL;
+        }
+}
+
+/*
+ * clean up after reading
+ */
+static void slow_work_runqueue_stop(struct seq_file *m, void *v)
+{
+        spin_unlock_irq(&slow_work_queue_lock);
+}
+
+static const struct seq_operations slow_work_runqueue_ops = {
+        .start          = slow_work_runqueue_start,
+        .stop           = slow_work_runqueue_stop,
+        .next           = slow_work_runqueue_next,
+        .show           = slow_work_runqueue_show,
+};
+
+/*
+ * open "/sys/kernel/debug/slow_work/runqueue" to list queue contents
+ */
+static int slow_work_runqueue_open(struct inode *inode, struct file *file)
+{
+        return seq_open(file, &slow_work_runqueue_ops);
+}
+
+const struct file_operations slow_work_runqueue_fops = {
+        .owner          = THIS_MODULE,
+        .open           = slow_work_runqueue_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = seq_release,
+};