Date:	Thu, 31 Dec 2015 12:35:57 +0100
From:	Thomas Schoebel-Theuer <tst@...oebel-theuer.de>
To:	linux-kernel@...r.kernel.org, tst@...oebel-theuer.de
Subject: [RFC 02/31] mars: add new module brick_say

Signed-off-by: Thomas Schoebel-Theuer <tst@...oebel-theuer.de>
---
 drivers/staging/mars/brick_say.c | 916 +++++++++++++++++++++++++++++++++++++++
 include/linux/brick/brick_say.h  |  96 ++++
 2 files changed, 1012 insertions(+)
 create mode 100644 drivers/staging/mars/brick_say.c
 create mode 100644 include/linux/brick/brick_say.h

diff --git a/drivers/staging/mars/brick_say.c b/drivers/staging/mars/brick_say.c
new file mode 100644
index 0000000..7a51273
--- /dev/null
+++ b/drivers/staging/mars/brick_say.c
@@ -0,0 +1,916 @@
+/*
+ * MARS Long Distance Replication Software
+ *
+ * Copyright (C) 2010-2014 Thomas Schoebel-Theuer
+ * Copyright (C) 2011-2014 1&1 Internet AG
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+
+#include <linux/brick/brick_say.h>
+#include <linux/brick/lamport.h>
+
+/*******************************************************************/
+
+/*  messaging */
+
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+#include <linux/file.h>
+#include <linux/sched.h>
+#include <linux/preempt.h>
+#include <linux/hardirq.h>
+#include <linux/smp.h>
+#include <linux/slab.h>
+#include <linux/kthread.h>
+#include <linux/syscalls.h>
+
+#include <linux/uaccess.h>
+
+#include <linux/brick/vfs_compat.h>
+
+#ifndef GFP_BRICK
+#define GFP_BRICK			GFP_NOIO
+#endif
+
+#define SAY_ORDER			0
+#define SAY_BUFMAX			(PAGE_SIZE << SAY_ORDER)
+#define SAY_BUF_LIMIT			(SAY_BUFMAX - 1500)
+#define MAX_FILELEN			16
+#define MAX_IDS				1000
+
+const char *say_class[MAX_SAY_CLASS] = {
+	[SAY_DEBUG] = "debug",
+	[SAY_INFO] = "info",
+	[SAY_WARN] = "warn",
+	[SAY_ERROR] = "error",
+	[SAY_FATAL] = "fatal",
+	[SAY_TOTAL] = "total",
+};
+
+int brick_say_logging = 1;
+
+module_param_named(say_logging, brick_say_logging, int, 0);
+int brick_say_debug;
+
+module_param_named(say_debug, brick_say_debug, int, 0);
+
+int brick_say_syslog_min = 1;
+int brick_say_syslog_max = -1;
+int brick_say_syslog_flood_class = 3;
+int brick_say_syslog_flood_limit = 20;
+int brick_say_syslog_flood_recovery = 300;
+
+int delay_say_on_overflow =
+#ifdef CONFIG_MARS_DEBUG
+	1;
+#else
+	0;
+#endif
+
+static atomic_t say_alloc_channels = ATOMIC_INIT(0);
+static atomic_t say_alloc_names = ATOMIC_INIT(0);
+static atomic_t say_alloc_pages = ATOMIC_INIT(0);
+
+static unsigned long flood_start_jiffies;
+static int flood_count;
+
+struct say_channel {
+	char *ch_name;
+	struct say_channel *ch_next;
+	spinlock_t ch_lock[MAX_SAY_CLASS];
+	char *ch_buf[MAX_SAY_CLASS][2];
+
+	short ch_index[MAX_SAY_CLASS];
+	struct file *ch_filp[MAX_SAY_CLASS][2];
+	int ch_overflow[MAX_SAY_CLASS];
+	bool ch_written[MAX_SAY_CLASS];
+	bool ch_rollover;
+	bool ch_must_exist;
+	bool ch_is_dir;
+	bool ch_delete;
+	int ch_status_written;
+	int ch_id_max;
+	void *ch_ids[MAX_IDS];
+
+	wait_queue_head_t ch_progress;
+};
+
+struct say_channel *default_channel;
+
+static struct say_channel *channel_list;
+
+static rwlock_t say_lock = __RW_LOCK_UNLOCKED(say_lock);
+
+static struct task_struct *say_thread;
+
+static DECLARE_WAIT_QUEUE_HEAD(say_event);
+
+bool say_dirty;
+
+#define use_atomic()							\
+	((preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK | HARDIRQ_MASK | NMI_MASK)) != 0 || irqs_disabled())
+
+static
+void wait_channel(struct say_channel *ch, int class)
+{
+	if (delay_say_on_overflow && ch->ch_index[class] > SAY_BUF_LIMIT) {
+		if (!use_atomic()) {
+			say_dirty = true;
+			wake_up_interruptible(&say_event);
+			wait_event_interruptible_timeout(ch->ch_progress,
+				ch->ch_index[class] < SAY_BUF_LIMIT,
+				HZ / 10);
+		}
+	}
+}
+
+static
+struct say_channel *find_channel(const void *id)
+{
+	struct say_channel *res = default_channel;
+	struct say_channel *ch;
+
+	read_lock(&say_lock);
+	for (ch = channel_list; ch; ch = ch->ch_next) {
+		int i;
+
+		for (i = 0; i < ch->ch_id_max; i++) {
+			if (ch->ch_ids[i] == id) {
+				res = ch;
+				goto found;
+			}
+		}
+	}
+found:
+	read_unlock(&say_lock);
+	return res;
+}
+
+static
+void _remove_binding(struct task_struct *whom)
+{
+	struct say_channel *ch;
+	int i;
+
+	for (ch = channel_list; ch; ch = ch->ch_next) {
+		for (i = 0; i < ch->ch_id_max; i++) {
+			if (ch->ch_ids[i] == whom)
+				ch->ch_ids[i] = NULL;
+		}
+	}
+}
+
+void bind_to_channel(struct say_channel *ch, struct task_struct *whom)
+{
+	int i;
+
+	write_lock(&say_lock);
+	_remove_binding(whom);
+	for (i = 0; i < ch->ch_id_max; i++) {
+		if (!ch->ch_ids[i]) {
+			ch->ch_ids[i] = whom;
+			goto done;
+		}
+	}
+	if (likely(ch->ch_id_max < MAX_IDS - 1))
+		ch->ch_ids[ch->ch_id_max++] = whom;
+	else
+		goto err;
+done:
+	write_unlock(&say_lock);
+	goto out_return;
+err:
+	write_unlock(&say_lock);
+
+	say_to(default_channel, SAY_ERROR, "ID overflow for thread '%s'\n", whom->comm);
+out_return:;
+}
+
+struct say_channel *get_binding(struct task_struct *whom)
+{
+	struct say_channel *ch;
+	int i;
+
+	read_lock(&say_lock);
+	for (ch = channel_list; ch; ch = ch->ch_next) {
+		for (i = 0; i < ch->ch_id_max; i++) {
+			if (ch->ch_ids[i] == whom)
+				goto found;
+		}
+	}
+	ch = NULL;
+found:
+	read_unlock(&say_lock);
+	return ch;
+}
+
+void remove_binding_from(struct say_channel *ch, struct task_struct *whom)
+{
+	bool found = false;
+	int i;
+
+	write_lock(&say_lock);
+	for (i = 0; i < ch->ch_id_max; i++) {
+		if (ch->ch_ids[i] == whom) {
+			ch->ch_ids[i] = NULL;
+			found = true;
+			break;
+		}
+	}
+	if (!found)
+		_remove_binding(whom);
+	write_unlock(&say_lock);
+}
+
+void remove_binding(struct task_struct *whom)
+{
+	write_lock(&say_lock);
+	_remove_binding(whom);
+	write_unlock(&say_lock);
+}
+
+void rollover_channel(struct say_channel *ch)
+{
+	if (!ch)
+		ch = find_channel(current);
+	if (likely(ch))
+		ch->ch_rollover = true;
+}
+
+void rollover_all(void)
+{
+	struct say_channel *ch;
+
+	read_lock(&say_lock);
+	for (ch = channel_list; ch; ch = ch->ch_next)
+		ch->ch_rollover = true;
+	read_unlock(&say_lock);
+}
+
+void del_channel(struct say_channel *ch)
+{
+	if (unlikely(!ch))
+		goto out_return;
+	if (unlikely(ch == default_channel)) {
+		say_to(default_channel, SAY_ERROR, "thread '%s' tried to delete the default channel\n", current->comm);
+		goto out_return;
+	}
+
+	ch->ch_delete = true;
+out_return:;
+}
+
+static
+void _del_channel(struct say_channel *ch)
+{
+	struct say_channel *tmp;
+	struct say_channel **_tmp;
+	int i, j;
+
+	if (!ch)
+		goto out_return;
+	write_lock(&say_lock);
+	for (_tmp = &channel_list; (tmp = *_tmp) != NULL; _tmp = &tmp->ch_next) {
+		if (tmp == ch) {
+			*_tmp = tmp->ch_next;
+			break;
+		}
+	}
+	write_unlock(&say_lock);
+
+	for (i = 0; i < MAX_SAY_CLASS; i++) {
+		for (j = 0; j < 2; j++) {
+			if (ch->ch_filp[i][j]) {
+				filp_close(ch->ch_filp[i][j], NULL);
+				ch->ch_filp[i][j] = NULL;
+			}
+		}
+		for (j = 0; j < 2; j++) {
+			char *buf = ch->ch_buf[i][j];
+
+			if (buf) {
+				__free_pages(virt_to_page((unsigned long)buf), SAY_ORDER);
+				atomic_dec(&say_alloc_pages);
+			}
+		}
+	}
+	if (ch->ch_name) {
+		atomic_dec(&say_alloc_names);
+		kfree(ch->ch_name);
+	}
+	kfree(ch);
+	atomic_dec(&say_alloc_channels);
+out_return:;
+}
+
+static
+struct say_channel *_make_channel(const char *name, bool must_exist)
+{
+	struct say_channel *res = NULL;
+	struct kstat kstat = {};
+	int i, j;
+	unsigned long mode = use_atomic() ? GFP_ATOMIC : GFP_BRICK;
+
+	mm_segment_t oldfs;
+	bool is_dir = false;
+	int status;
+
+	oldfs = get_fs();
+	set_fs(get_ds());
+	status = vfs_stat((char *)name, &kstat);
+	set_fs(oldfs);
+
+	if (unlikely(status < 0)) {
+		if (must_exist) {
+			say(SAY_ERROR, "cannot create channel '%s', status = %d\n", name, status);
+			goto done;
+		}
+	} else {
+		is_dir = S_ISDIR(kstat.mode);
+	}
+
+restart:
+	res = kzalloc(sizeof(struct say_channel), mode);
+	if (unlikely(!res)) {
+		schedule();
+		goto restart;
+	}
+	atomic_inc(&say_alloc_channels);
+	res->ch_must_exist = must_exist;
+	res->ch_is_dir = is_dir;
+	init_waitqueue_head(&res->ch_progress);
+restart2:
+	res->ch_name = kstrdup(name, mode);
+	if (unlikely(!res->ch_name)) {
+		schedule();
+		goto restart2;
+	}
+	atomic_inc(&say_alloc_names);
+	for (i = 0; i < MAX_SAY_CLASS; i++) {
+		spin_lock_init(&res->ch_lock[i]);
+		for (j = 0; j < 2; j++) {
+			char *buf;
+
+restart3:
+			buf = (void *)__get_free_pages(mode, SAY_ORDER);
+			if (unlikely(!buf)) {
+				schedule();
+				goto restart3;
+			}
+			atomic_inc(&say_alloc_pages);
+			res->ch_buf[i][j] = buf;
+		}
+	}
+done:
+	return res;
+}
+
+struct say_channel *make_channel(const char *name, bool must_exist)
+{
+	struct say_channel *res = NULL;
+	struct say_channel *ch;
+
+	read_lock(&say_lock);
+	for (ch = channel_list; ch; ch = ch->ch_next) {
+		if (!strcmp(ch->ch_name, name)) {
+			res = ch;
+			break;
+		}
+	}
+	read_unlock(&say_lock);
+
+	if (unlikely(!res)) {
+		res = _make_channel(name, must_exist);
+		if (unlikely(!res))
+			goto done;
+
+		write_lock(&say_lock);
+
+		for (ch = channel_list; ch; ch = ch->ch_next) {
+			if (ch != res && unlikely(!strcmp(ch->ch_name, name))) {
+				_del_channel(res);
+				res = ch;
+				goto race_found;
+			}
+		}
+
+		res->ch_next = channel_list;
+		channel_list = res;
+
+race_found:
+		write_unlock(&say_lock);
+	}
+
+done:
+	return res;
+}
+
+/*  tell gcc to check for varargs errors */
+static
+void _say(struct say_channel *ch, int class, va_list args, bool use_args, const char *fmt, ...)  __printf(5, 6);
+
+static
+void _say(struct say_channel *ch, int class, va_list args, bool use_args, const char *fmt, ...)
+{
+	char *start;
+	int offset;
+	int rest;
+	int written;
+
+	if (unlikely(!ch))
+		goto out_return;
+	if (unlikely(ch->ch_delete && ch != default_channel)) {
+		say_to(default_channel, SAY_ERROR, "thread '%s' tried to write on deleted channel\n", current->comm);
+		goto out_return;
+	}
+
+	offset = ch->ch_index[class];
+	start = ch->ch_buf[class][0] + offset;
+	rest = SAY_BUFMAX - 1 - offset;
+	if (unlikely(rest <= 0)) {
+		ch->ch_overflow[class]++;
+		goto out_return;
+	}
+
+	if (use_args) {
+		va_list args2;
+
+		va_start(args2, fmt);
+		written = vscnprintf(start, rest, fmt, args2);
+		va_end(args2);
+	} else {
+		written = vscnprintf(start, rest, fmt, args);
+	}
+
+	if (likely(rest > written)) {
+		start[written] = '\0';
+		ch->ch_index[class] += written;
+		say_dirty = true;
+	} else {
+		/*  indicate overflow */
+		start[0] = '\0';
+		ch->ch_overflow[class]++;
+	}
+out_return:;
+}
+
+void say_to(struct say_channel *ch, int class, const char *fmt, ...)
+{
+	va_list args;
+	unsigned long flags;
+
+	if (!class && !brick_say_debug)
+		goto out_return;
+	if (!ch)
+		ch = find_channel(current);
+
+	if (likely(ch)) {
+		if (!ch->ch_is_dir)
+			class = SAY_TOTAL;
+		if (likely(class >= 0 && class < MAX_SAY_CLASS)) {
+			wait_channel(ch, class);
+			spin_lock_irqsave(&ch->ch_lock[class], flags);
+
+			va_start(args, fmt);
+			_say(ch, class, args, false, fmt);
+			va_end(args);
+
+			spin_unlock_irqrestore(&ch->ch_lock[class], flags);
+		}
+	}
+
+	ch = default_channel;
+	if (likely(ch)) {
+		class = SAY_TOTAL;
+		wait_channel(ch, class);
+		spin_lock_irqsave(&ch->ch_lock[class], flags);
+
+		va_start(args, fmt);
+		_say(ch, class, args, false, fmt);
+		va_end(args);
+
+		spin_unlock_irqrestore(&ch->ch_lock[class], flags);
+
+		wake_up_interruptible(&say_event);
+	}
+out_return:;
+}
+
+void brick_say_to(struct say_channel *ch,
+	int class,
+	bool dump,
+	const char *prefix,
+	const char *file,
+	int line,
+	const char *func,
+	const char *fmt,
+	...)
+{
+	const char *channel_name = "-";
+	struct timespec s_now;
+	struct timespec l_now;
+	int filelen;
+	int orig_class;
+	va_list args;
+	unsigned long flags;
+
+	if (!class && !brick_say_debug)
+		goto out_return;
+	s_now = CURRENT_TIME;
+	get_lamport(&l_now);
+
+	if (!ch)
+		ch = find_channel(current);
+
+	orig_class = class;
+
+	/*  limit the filename */
+	filelen = strlen(file);
+	if (filelen > MAX_FILELEN)
+		file += filelen - MAX_FILELEN;
+
+	if (likely(ch)) {
+		channel_name = ch->ch_name;
+		if (!ch->ch_is_dir)
+			class = SAY_TOTAL;
+		if (likely(class >= 0 && class < MAX_SAY_CLASS)) {
+			wait_channel(ch, class);
+			spin_lock_irqsave(&ch->ch_lock[class], flags);
+
+			_say(ch, class, NULL, true,
+			     "%ld.%09ld %ld.%09ld %s %s[%d] %s:%d %s(): ",
+			     s_now.tv_sec, s_now.tv_nsec,
+			     l_now.tv_sec, l_now.tv_nsec,
+			     prefix,
+			     current->comm, (int)smp_processor_id(),
+			     file, line,
+			     func);
+
+			va_start(args, fmt);
+			_say(ch, class, args, false, fmt);
+			va_end(args);
+
+			spin_unlock_irqrestore(&ch->ch_lock[class], flags);
+		}
+	}
+
+	ch = default_channel;
+	if (likely(ch)) {
+		wait_channel(ch, SAY_TOTAL);
+		spin_lock_irqsave(&ch->ch_lock[SAY_TOTAL], flags);
+
+		_say(ch, SAY_TOTAL, NULL, true,
+		     "%ld.%09ld %ld.%09ld %s_%-5s %s %s[%d] %s:%d %s(): ",
+		     s_now.tv_sec, s_now.tv_nsec,
+		     l_now.tv_sec, l_now.tv_nsec,
+		     prefix, say_class[orig_class],
+		     channel_name,
+		     current->comm, (int)smp_processor_id(),
+		     file, line,
+		     func);
+
+		va_start(args, fmt);
+		_say(ch, SAY_TOTAL, args, false, fmt);
+		va_end(args);
+
+		spin_unlock_irqrestore(&ch->ch_lock[SAY_TOTAL], flags);
+
+	}
+#ifdef CONFIG_MARS_DEBUG
+	if (dump)
+		brick_dump_stack();
+#endif
+	wake_up_interruptible(&say_event);
+out_return:;
+}
+
+static
+void try_open_file(struct file **file, char *filename, bool creat)
+{
+	struct address_space *mapping;
+	int flags = O_APPEND | O_WRONLY | O_LARGEFILE;
+	int prot = 0600;
+
+	if (creat)
+		flags |= O_CREAT;
+
+	*file = filp_open(filename, flags, prot);
+	if (unlikely(IS_ERR(*file))) {
+		*file = NULL;
+		goto out_return;
+	}
+	mapping = (*file)->f_mapping;
+	if (likely(mapping))
+		mapping_set_gfp_mask(mapping, mapping_gfp_mask(mapping) & ~(__GFP_IO | __GFP_FS));
+out_return:;
+}
+
+static
+void out_to_file(struct file *file, char *buf, int len)
+{
+	loff_t log_pos = 0;
+
+	mm_segment_t oldfs;
+
+	if (file) {
+		oldfs = get_fs();
+		set_fs(get_ds());
+		(void)vfs_write(file, buf, len, &log_pos);
+		set_fs(oldfs);
+	}
+}
+
+static inline
+void reset_flood(void)
+{
+	if (flood_start_jiffies &&
+	    time_is_before_jiffies(flood_start_jiffies + brick_say_syslog_flood_recovery * HZ)) {
+		flood_start_jiffies = 0;
+		flood_count = 0;
+	}
+}
+
+static
+void printk_with_class(int class, char *buf)
+{
+	switch (class) {
+	case SAY_INFO:
+		printk(KERN_INFO "%s", buf);
+		break;
+	case SAY_WARN:
+		printk(KERN_WARNING "%s", buf);
+		break;
+	case SAY_ERROR:
+	case SAY_FATAL:
+		printk(KERN_ERR "%s", buf);
+		break;
+	default:
+		printk(KERN_DEBUG "%s", buf);
+	}
+}
+
+static
+void out_to_syslog(int class, char *buf, int len)
+{
+	reset_flood();
+	if (class >= brick_say_syslog_min && class <= brick_say_syslog_max) {
+		buf[len] = '\0';
+		printk_with_class(class, buf);
+	} else if (class >= brick_say_syslog_flood_class && brick_say_syslog_flood_class >= 0 && class != SAY_TOTAL) {
+		flood_start_jiffies = jiffies;
+		if (++flood_count <= brick_say_syslog_flood_limit) {
+			buf[len] = '\0';
+			printk_with_class(class, buf);
+		}
+	}
+}
+
+static inline
+char *_make_filename(struct say_channel *ch, int class, int transact, int add_tmp)
+{
+	char *filename;
+
+restart:
+	filename = kmalloc(1024, GFP_KERNEL);
+	if (unlikely(!filename)) {
+		schedule();
+		goto restart;
+	}
+	atomic_inc(&say_alloc_names);
+	if (ch->ch_is_dir) {
+		snprintf(filename,
+			1023,
+			"%s/%d.%s.%s%s",
+			ch->ch_name,
+			class,
+			say_class[class],
+			transact ? "status" : "log",
+			add_tmp ? ".tmp" : "");
+	} else {
+		snprintf(filename, 1023, "%s.%s%s", ch->ch_name, transact ? "status" : "log", add_tmp ? ".tmp" : "");
+	}
+	return filename;
+}
+
+static
+void _rollover_channel(struct say_channel *ch)
+{
+	int start = 0;
+	int class;
+
+	ch->ch_rollover = false;
+	ch->ch_status_written = 0;
+
+	if (!ch->ch_is_dir)
+		start = SAY_TOTAL;
+
+	for (class = start; class < MAX_SAY_CLASS; class++) {
+		char *old = _make_filename(ch, class, 1, 1);
+		char *new = _make_filename(ch, class, 1, 0);
+
+		if (likely(old && new)) {
+			int i;
+
+			mm_segment_t oldfs;
+
+			for (i = 0; i < 2; i++) {
+				if (ch->ch_filp[class][i]) {
+					filp_close(ch->ch_filp[class][i], NULL);
+					ch->ch_filp[class][i] = NULL;
+				}
+			}
+
+			oldfs = get_fs();
+			set_fs(get_ds());
+#ifdef __USE_COMPAT
+			_compat_rename(old, new);
+#else
+			sys_rename(old, new);
+#endif
+			set_fs(oldfs);
+		}
+
+		if (likely(old)) {
+			kfree(old);
+			atomic_dec(&say_alloc_names);
+		}
+		if (likely(new)) {
+			kfree(new);
+			atomic_dec(&say_alloc_names);
+		}
+	}
+}
+
+static
+void treat_channel(struct say_channel *ch, int class)
+{
+	int len;
+	int overflow;
+	int transact;
+	int start;
+	char *buf;
+	char *tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ch->ch_lock[class], flags);
+
+	buf = ch->ch_buf[class][0];
+	tmp = ch->ch_buf[class][1];
+	ch->ch_buf[class][1] = buf;
+	ch->ch_buf[class][0] = tmp;
+	len = ch->ch_index[class];
+	ch->ch_index[class] = 0;
+	overflow = ch->ch_overflow[class];
+	ch->ch_overflow[class] = 0;
+
+	spin_unlock_irqrestore(&ch->ch_lock[class], flags);
+
+	wake_up_interruptible(&ch->ch_progress);
+
+	ch->ch_status_written += len;
+	out_to_syslog(class, buf, len);
+	start = 0;
+	if (!brick_say_logging)
+		start++;
+	for (transact = start; transact < 2; transact++) {
+		if (unlikely(!ch->ch_filp[class][transact])) {
+			char *filename = _make_filename(ch, class, transact, transact);
+
+			if (likely(filename)) {
+				try_open_file(&ch->ch_filp[class][transact], filename, transact);
+				kfree(filename);
+				atomic_dec(&say_alloc_names);
+			}
+		}
+		out_to_file(ch->ch_filp[class][transact], buf, len);
+	}
+
+	if (unlikely(overflow > 0)) {
+		struct timespec s_now = CURRENT_TIME;
+		struct timespec l_now;
+
+		get_lamport(&l_now);
+		len = scnprintf(buf,
+			       SAY_BUFMAX,
+			       "%ld.%09ld %ld.%09ld %s %d OVERFLOW %d times\n",
+			       s_now.tv_sec, s_now.tv_nsec,
+			       l_now.tv_sec, l_now.tv_nsec,
+			       ch->ch_name,
+			       class,
+			       overflow);
+		ch->ch_status_written += len;
+		out_to_syslog(class, buf, len);
+		for (transact = 0; transact < 2; transact++)
+			out_to_file(ch->ch_filp[class][transact], buf, len);
+	}
+}
+
+static
+int _say_thread(void *data)
+{
+	while (!kthread_should_stop()) {
+		struct say_channel *ch;
+		int i;
+
+		wait_event_interruptible_timeout(say_event, say_dirty, HZ);
+		say_dirty = false;
+
+restart_rollover:
+		read_lock(&say_lock);
+		for (ch = channel_list; ch; ch = ch->ch_next) {
+			if (ch->ch_rollover && ch->ch_status_written > 0) {
+				read_unlock(&say_lock);
+				_rollover_channel(ch);
+				goto restart_rollover;
+			}
+		}
+		read_unlock(&say_lock);
+
+restart:
+		read_lock(&say_lock);
+		for (ch = channel_list; ch; ch = ch->ch_next) {
+			int start = 0;
+
+			if (!ch->ch_is_dir)
+				start = SAY_TOTAL;
+			for (i = start; i < MAX_SAY_CLASS; i++) {
+				if (ch->ch_index[i] > 0) {
+					read_unlock(&say_lock);
+					treat_channel(ch, i);
+					goto restart;
+				}
+			}
+			if (ch->ch_delete) {
+				read_unlock(&say_lock);
+				_del_channel(ch);
+				goto restart;
+			}
+		}
+		read_unlock(&say_lock);
+	}
+
+	return 0;
+}
+
+void init_say(void)
+{
+	default_channel = make_channel(CONFIG_MARS_LOGDIR, true);
+	say_thread = kthread_create(_say_thread, NULL, "brick_say");
+	if (IS_ERR(say_thread)) {
+		say_thread = NULL;
+	} else {
+		get_task_struct(say_thread);
+		wake_up_process(say_thread);
+	}
+
+}
+
+void exit_say(void)
+{
+	int memleak_channels;
+	int memleak_names;
+	int memleak_pages;
+
+	if (say_thread) {
+		kthread_stop(say_thread);
+		put_task_struct(say_thread);
+		say_thread = NULL;
+	}
+
+	default_channel = NULL;
+	while (channel_list)
+		_del_channel(channel_list);
+
+	memleak_channels = atomic_read(&say_alloc_channels);
+	memleak_names = atomic_read(&say_alloc_names);
+	memleak_pages = atomic_read(&say_alloc_pages);
+	if (unlikely(memleak_channels || memleak_names || memleak_pages))
+		printk("MEMLEAK: channels=%d names=%d pages=%d\n", memleak_channels, memleak_names, memleak_pages);
+}
+
+#ifdef CONFIG_MARS_DEBUG
+
+static int dump_max = 5;
+
+void brick_dump_stack(void)
+{
+	if (dump_max > 0) {
+		dump_max--; /*	racy, but does no harm */
+		dump_stack();
+	}
+}
+
+#endif
diff --git a/include/linux/brick/brick_say.h b/include/linux/brick/brick_say.h
new file mode 100644
index 0000000..d0f15f6
--- /dev/null
+++ b/include/linux/brick/brick_say.h
@@ -0,0 +1,96 @@
+/*
+ * MARS Long Distance Replication Software
+ *
+ * Copyright (C) 2010-2014 Thomas Schoebel-Theuer
+ * Copyright (C) 2011-2014 1&1 Internet AG
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef BRICK_SAY_H
+#define BRICK_SAY_H
+
+/***********************************************************************/
+
+extern int brick_say_logging;
+extern int brick_say_debug;
+extern int brick_say_syslog_min;
+extern int brick_say_syslog_max;
+extern int brick_say_syslog_flood_class;
+extern int brick_say_syslog_flood_limit;
+extern int brick_say_syslog_flood_recovery;
+extern int delay_say_on_overflow;
+
+/*  printk() replacements */
+
+enum {
+	SAY_DEBUG,
+	SAY_INFO,
+	SAY_WARN,
+	SAY_ERROR,
+	SAY_FATAL,
+	SAY_TOTAL,
+	MAX_SAY_CLASS
+};
+
+extern const char *say_class[MAX_SAY_CLASS];
+
+struct say_channel;
+
+extern struct say_channel *default_channel;
+
+extern struct say_channel *make_channel(const char *name, bool must_exit);
+
+extern void del_channel(struct say_channel *ch);
+
+extern void bind_to_channel(struct say_channel *ch, struct task_struct *whom);
+
+#define bind_me(_name)							\
+	bind_to_channel(make_channel(_name), current)
+
+extern struct say_channel *get_binding(struct task_struct *whom);
+
+extern void remove_binding_from(struct say_channel *ch, struct task_struct *whom);
+extern void remove_binding(struct task_struct *whom);
+
+extern void rollover_channel(struct say_channel *ch);
+extern void rollover_all(void);
+
+extern void say_to(struct say_channel *ch, int class, const char *fmt, ...) __printf(3, 4);
+
+#define say(_class, _fmt, _args...)					\
+	say_to(NULL, _class, _fmt, ##_args)
+
+extern void brick_say_to(struct say_channel *ch,
+	int class,
+	bool dump,
+	const char *prefix,
+	const char *file,
+	int line,
+	const char *func,
+	const char *fmt,
+
+	...) __printf(8,
+	9);
+
+#define brick_say(_class, _dump, _prefix, _file, _line, _func, _fmt, _args...)\
+	brick_say_to(NULL, _class, _dump, _prefix, _file, _line, _func, _fmt, ##_args)
+
+extern void init_say(void);
+extern void exit_say(void);
+
+#ifdef CONFIG_MARS_DEBUG
+extern void brick_dump_stack(void);
+#else /*  CONFIG_MARS_DEBUG */
+#define brick_dump_stack() /*empty*/
+#endif /*  CONFIG_MARS_DEBUG */
+
+#endif
-- 
2.6.4

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