Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 996 insertions, 0 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
new file mode 100644
index 0000000..1498689
--- /dev/null
+++ b/kernel/printk.c
@@ -0,0 +1,996 @@
+/*
+ *  linux/kernel/printk.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ * Modified to make sys_syslog() more flexible: added commands to
+ * return the last 4k of kernel messages, regardless of whether
+ * they've been read or not.  Added option to suppress kernel printk's
+ * to the console.  Added hook for sending the console messages
+ * elsewhere, in preparation for a serial line console (someday).
+ * Ted Ts'o, 2/11/93.
+ * Modified for sysctl support, 1/8/97, Chris Horn.
+ * Fixed SMP synchronization, 08/08/99, Manfred Spraul 
+ *     manfreds@colorfullife.com
+ * Rewrote bits to get rid of console_lock
+ *	01Mar01 Andrew Morton <andrewm@uow.edu.au>
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/smp_lock.h>
+#include <linux/console.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>			/* For in_interrupt() */
+#include <linux/config.h>
+#include <linux/delay.h>
+#include <linux/smp.h>
+#include <linux/security.h>
+#include <linux/bootmem.h>
+#include <linux/syscalls.h>
+
+#include <asm/uaccess.h>
+
+#define __LOG_BUF_LEN	(1 << CONFIG_LOG_BUF_SHIFT)
+
+/* printk's without a loglevel use this.. */
+#define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */
+
+/* We show everything that is MORE important than this.. */
+#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
+#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
+
+DECLARE_WAIT_QUEUE_HEAD(log_wait);
+
+int console_printk[4] = {
+	DEFAULT_CONSOLE_LOGLEVEL,	/* console_loglevel */
+	DEFAULT_MESSAGE_LOGLEVEL,	/* default_message_loglevel */
+	MINIMUM_CONSOLE_LOGLEVEL,	/* minimum_console_loglevel */
+	DEFAULT_CONSOLE_LOGLEVEL,	/* default_console_loglevel */
+};
+
+EXPORT_SYMBOL(console_printk);
+
+/*
+ * Low lever drivers may need that to know if they can schedule in
+ * their unblank() callback or not. So let's export it.
+ */
+int oops_in_progress;
+EXPORT_SYMBOL(oops_in_progress);
+
+/*
+ * console_sem protects the console_drivers list, and also
+ * provides serialisation for access to the entire console
+ * driver system.
+ */
+static DECLARE_MUTEX(console_sem);
+struct console *console_drivers;
+/*
+ * This is used for debugging the mess that is the VT code by
+ * keeping track if we have the console semaphore held. It's
+ * definitely not the perfect debug tool (we don't know if _WE_
+ * hold it are racing, but it helps tracking those weird code
+ * path in the console code where we end up in places I want
+ * locked without the console sempahore held
+ */
+static int console_locked;
+
+/*
+ * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars
+ * It is also used in interesting ways to provide interlocking in
+ * release_console_sem().
+ */
+static DEFINE_SPINLOCK(logbuf_lock);
+
+static char __log_buf[__LOG_BUF_LEN];
+static char *log_buf = __log_buf;
+static int log_buf_len = __LOG_BUF_LEN;
+
+#define LOG_BUF_MASK	(log_buf_len-1)
+#define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK])
+
+/*
+ * The indices into log_buf are not constrained to log_buf_len - they
+ * must be masked before subscripting
+ */
+static unsigned long log_start;	/* Index into log_buf: next char to be read by syslog() */
+static unsigned long con_start;	/* Index into log_buf: next char to be sent to consoles */
+static unsigned long log_end;	/* Index into log_buf: most-recently-written-char + 1 */
+static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */
+
+/*
+ *	Array of consoles built from command line options (console=)
+ */
+struct console_cmdline
+{
+	char	name[8];			/* Name of the driver	    */
+	int	index;				/* Minor dev. to use	    */
+	char	*options;			/* Options for the driver   */
+};
+
+#define MAX_CMDLINECONSOLES 8
+
+static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
+static int selected_console = -1;
+static int preferred_console = -1;
+
+/* Flag: console code may call schedule() */
+static int console_may_schedule;
+
+/*
+ *	Setup a list of consoles. Called from init/main.c
+ */
+static int __init console_setup(char *str)
+{
+	char name[sizeof(console_cmdline[0].name)];
+	char *s, *options;
+	int idx;
+
+	/*
+	 *	Decode str into name, index, options.
+	 */
+	if (str[0] >= '0' && str[0] <= '9') {
+		strcpy(name, "ttyS");
+		strncpy(name + 4, str, sizeof(name) - 5);
+	} else
+		strncpy(name, str, sizeof(name) - 1);
+	name[sizeof(name) - 1] = 0;
+	if ((options = strchr(str, ',')) != NULL)
+		*(options++) = 0;
+#ifdef __sparc__
+	if (!strcmp(str, "ttya"))
+		strcpy(name, "ttyS0");
+	if (!strcmp(str, "ttyb"))
+		strcpy(name, "ttyS1");
+#endif
+	for(s = name; *s; s++)
+		if ((*s >= '0' && *s <= '9') || *s == ',')
+			break;
+	idx = simple_strtoul(s, NULL, 10);
+	*s = 0;
+
+	add_preferred_console(name, idx, options);
+	return 1;
+}
+
+__setup("console=", console_setup);
+
+/**
+ * add_preferred_console - add a device to the list of preferred consoles.
+ *
+ * The last preferred console added will be used for kernel messages
+ * and stdin/out/err for init.  Normally this is used by console_setup
+ * above to handle user-supplied console arguments; however it can also
+ * be used by arch-specific code either to override the user or more
+ * commonly to provide a default console (ie from PROM variables) when
+ * the user has not supplied one.
+ */
+int __init add_preferred_console(char *name, int idx, char *options)
+{
+	struct console_cmdline *c;
+	int i;
+
+	/*
+	 *	See if this tty is not yet registered, and
+	 *	if we have a slot free.
+	 */
+	for(i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
+		if (strcmp(console_cmdline[i].name, name) == 0 &&
+			  console_cmdline[i].index == idx) {
+				selected_console = i;
+				return 0;
+		}
+	if (i == MAX_CMDLINECONSOLES)
+		return -E2BIG;
+	selected_console = i;
+	c = &console_cmdline[i];
+	memcpy(c->name, name, sizeof(c->name));
+	c->name[sizeof(c->name) - 1] = 0;
+	c->options = options;
+	c->index = idx;
+	return 0;
+}
+
+static int __init log_buf_len_setup(char *str)
+{
+	unsigned long size = memparse(str, &str);
+	unsigned long flags;
+
+	if (size)
+		size = roundup_pow_of_two(size);
+	if (size > log_buf_len) {
+		unsigned long start, dest_idx, offset;
+		char * new_log_buf;
+
+		new_log_buf = alloc_bootmem(size);
+		if (!new_log_buf) {
+			printk("log_buf_len: allocation failed\n");
+			goto out;
+		}
+
+		spin_lock_irqsave(&logbuf_lock, flags);
+		log_buf_len = size;
+		log_buf = new_log_buf;
+
+		offset = start = min(con_start, log_start);
+		dest_idx = 0;
+		while (start != log_end) {
+			log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)];
+			start++;
+			dest_idx++;
+		}
+		log_start -= offset;
+		con_start -= offset;
+		log_end -= offset;
+		spin_unlock_irqrestore(&logbuf_lock, flags);
+
+		printk("log_buf_len: %d\n", log_buf_len);
+	}
+out:
+
+	return 1;
+}
+
+__setup("log_buf_len=", log_buf_len_setup);
+
+/*
+ * Commands to do_syslog:
+ *
+ * 	0 -- Close the log.  Currently a NOP.
+ * 	1 -- Open the log. Currently a NOP.
+ * 	2 -- Read from the log.
+ * 	3 -- Read all messages remaining in the ring buffer.
+ * 	4 -- Read and clear all messages remaining in the ring buffer
+ * 	5 -- Clear ring buffer.
+ * 	6 -- Disable printk's to console
+ * 	7 -- Enable printk's to console
+ *	8 -- Set level of messages printed to console
+ *	9 -- Return number of unread characters in the log buffer
+ *     10 -- Return size of the log buffer
+ */
+int do_syslog(int type, char __user * buf, int len)
+{
+	unsigned long i, j, limit, count;
+	int do_clear = 0;
+	char c;
+	int error = 0;
+
+	error = security_syslog(type);
+	if (error)
+		return error;
+
+	switch (type) {
+	case 0:		/* Close log */
+		break;
+	case 1:		/* Open log */
+		break;
+	case 2:		/* Read from log */
+		error = -EINVAL;
+		if (!buf || len < 0)
+			goto out;
+		error = 0;
+		if (!len)
+			goto out;
+		if (!access_ok(VERIFY_WRITE, buf, len)) {
+			error = -EFAULT;
+			goto out;
+		}
+		error = wait_event_interruptible(log_wait, (log_start - log_end));
+		if (error)
+			goto out;
+		i = 0;
+		spin_lock_irq(&logbuf_lock);
+		while (!error && (log_start != log_end) && i < len) {
+			c = LOG_BUF(log_start);
+			log_start++;
+			spin_unlock_irq(&logbuf_lock);
+			error = __put_user(c,buf);
+			buf++;
+			i++;
+			cond_resched();
+			spin_lock_irq(&logbuf_lock);
+		}
+		spin_unlock_irq(&logbuf_lock);
+		if (!error)
+			error = i;
+		break;
+	case 4:		/* Read/clear last kernel messages */
+		do_clear = 1; 
+		/* FALL THRU */
+	case 3:		/* Read last kernel messages */
+		error = -EINVAL;
+		if (!buf || len < 0)
+			goto out;
+		error = 0;
+		if (!len)
+			goto out;
+		if (!access_ok(VERIFY_WRITE, buf, len)) {
+			error = -EFAULT;
+			goto out;
+		}
+		count = len;
+		if (count > log_buf_len)
+			count = log_buf_len;
+		spin_lock_irq(&logbuf_lock);
+		if (count > logged_chars)
+			count = logged_chars;
+		if (do_clear)
+			logged_chars = 0;
+		limit = log_end;
+		/*
+		 * __put_user() could sleep, and while we sleep
+		 * printk() could overwrite the messages 
+		 * we try to copy to user space. Therefore
+		 * the messages are copied in reverse. <manfreds>
+		 */
+		for(i = 0; i < count && !error; i++) {
+			j = limit-1-i;
+			if (j + log_buf_len < log_end)
+				break;
+			c = LOG_BUF(j);
+			spin_unlock_irq(&logbuf_lock);
+			error = __put_user(c,&buf[count-1-i]);
+			cond_resched();
+			spin_lock_irq(&logbuf_lock);
+		}
+		spin_unlock_irq(&logbuf_lock);
+		if (error)
+			break;
+		error = i;
+		if(i != count) {
+			int offset = count-error;
+			/* buffer overflow during copy, correct user buffer. */
+			for(i=0;i<error;i++) {
+				if (__get_user(c,&buf[i+offset]) ||
+				    __put_user(c,&buf[i])) {
+					error = -EFAULT;
+					break;
+				}
+				cond_resched();
+			}
+		}
+		break;
+	case 5:		/* Clear ring buffer */
+		logged_chars = 0;
+		break;
+	case 6:		/* Disable logging to console */
+		console_loglevel = minimum_console_loglevel;
+		break;
+	case 7:		/* Enable logging to console */
+		console_loglevel = default_console_loglevel;
+		break;
+	case 8:		/* Set level of messages printed to console */
+		error = -EINVAL;
+		if (len < 1 || len > 8)
+			goto out;
+		if (len < minimum_console_loglevel)
+			len = minimum_console_loglevel;
+		console_loglevel = len;
+		error = 0;
+		break;
+	case 9:		/* Number of chars in the log buffer */
+		error = log_end - log_start;
+		break;
+	case 10:	/* Size of the log buffer */
+		error = log_buf_len;
+		break;
+	default:
+		error = -EINVAL;
+		break;
+	}
+out:
+	return error;
+}
+
+asmlinkage long sys_syslog(int type, char __user * buf, int len)
+{
+	return do_syslog(type, buf, len);
+}
+
+/*
+ * Call the console drivers on a range of log_buf
+ */
+static void __call_console_drivers(unsigned long start, unsigned long end)
+{
+	struct console *con;
+
+	for (con = console_drivers; con; con = con->next) {
+		if ((con->flags & CON_ENABLED) && con->write)
+			con->write(con, &LOG_BUF(start), end - start);
+	}
+}
+
+/*
+ * Write out chars from start to end - 1 inclusive
+ */
+static void _call_console_drivers(unsigned long start,
+				unsigned long end, int msg_log_level)
+{
+	if (msg_log_level < console_loglevel &&
+			console_drivers && start != end) {
+		if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) {
+			/* wrapped write */
+			__call_console_drivers(start & LOG_BUF_MASK,
+						log_buf_len);
+			__call_console_drivers(0, end & LOG_BUF_MASK);
+		} else {
+			__call_console_drivers(start, end);
+		}
+	}
+}
+
+/*
+ * Call the console drivers, asking them to write out
+ * log_buf[start] to log_buf[end - 1].
+ * The console_sem must be held.
+ */
+static void call_console_drivers(unsigned long start, unsigned long end)
+{
+	unsigned long cur_index, start_print;
+	static int msg_level = -1;
+
+	if (((long)(start - end)) > 0)
+		BUG();
+
+	cur_index = start;
+	start_print = start;
+	while (cur_index != end) {
+		if (	msg_level < 0 &&
+			((end - cur_index) > 2) &&
+			LOG_BUF(cur_index + 0) == '<' &&
+			LOG_BUF(cur_index + 1) >= '0' &&
+			LOG_BUF(cur_index + 1) <= '7' &&
+			LOG_BUF(cur_index + 2) == '>')
+		{
+			msg_level = LOG_BUF(cur_index + 1) - '0';
+			cur_index += 3;
+			start_print = cur_index;
+		}
+		while (cur_index != end) {
+			char c = LOG_BUF(cur_index);
+			cur_index++;
+
+			if (c == '\n') {
+				if (msg_level < 0) {
+					/*
+					 * printk() has already given us loglevel tags in
+					 * the buffer.  This code is here in case the
+					 * log buffer has wrapped right round and scribbled
+					 * on those tags
+					 */
+					msg_level = default_message_loglevel;
+				}
+				_call_console_drivers(start_print, cur_index, msg_level);
+				msg_level = -1;
+				start_print = cur_index;
+				break;
+			}
+		}
+	}
+	_call_console_drivers(start_print, end, msg_level);
+}
+
+static void emit_log_char(char c)
+{
+	LOG_BUF(log_end) = c;
+	log_end++;
+	if (log_end - log_start > log_buf_len)
+		log_start = log_end - log_buf_len;
+	if (log_end - con_start > log_buf_len)
+		con_start = log_end - log_buf_len;
+	if (logged_chars < log_buf_len)
+		logged_chars++;
+}
+
+/*
+ * Zap console related locks when oopsing. Only zap at most once
+ * every 10 seconds, to leave time for slow consoles to print a
+ * full oops.
+ */
+static void zap_locks(void)
+{
+	static unsigned long oops_timestamp;
+
+	if (time_after_eq(jiffies, oops_timestamp) &&
+			!time_after(jiffies, oops_timestamp + 30*HZ))
+		return;
+
+	oops_timestamp = jiffies;
+
+	/* If a crash is occurring, make sure we can't deadlock */
+	spin_lock_init(&logbuf_lock);
+	/* And make sure that we print immediately */
+	init_MUTEX(&console_sem);
+}
+
+#if defined(CONFIG_PRINTK_TIME)
+static int printk_time = 1;
+#else
+static int printk_time = 0;
+#endif
+
+static int __init printk_time_setup(char *str)
+{
+	if (*str)
+		return 0;
+	printk_time = 1;
+	return 1;
+}
+
+__setup("time", printk_time_setup);
+
+/*
+ * This is printk.  It can be called from any context.  We want it to work.
+ * 
+ * We try to grab the console_sem.  If we succeed, it's easy - we log the output and
+ * call the console drivers.  If we fail to get the semaphore we place the output
+ * into the log buffer and return.  The current holder of the console_sem will
+ * notice the new output in release_console_sem() and will send it to the
+ * consoles before releasing the semaphore.
+ *
+ * One effect of this deferred printing is that code which calls printk() and
+ * then changes console_loglevel may break. This is because console_loglevel
+ * is inspected when the actual printing occurs.
+ */
+asmlinkage int printk(const char *fmt, ...)
+{
+	va_list args;
+	int r;
+
+	va_start(args, fmt);
+	r = vprintk(fmt, args);
+	va_end(args);
+
+	return r;
+}
+
+asmlinkage int vprintk(const char *fmt, va_list args)
+{
+	unsigned long flags;
+	int printed_len;
+	char *p;
+	static char printk_buf[1024];
+	static int log_level_unknown = 1;
+
+	if (unlikely(oops_in_progress))
+		zap_locks();
+
+	/* This stops the holder of console_sem just where we want him */
+	spin_lock_irqsave(&logbuf_lock, flags);
+
+	/* Emit the output into the temporary buffer */
+	printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args);
+
+	/*
+	 * Copy the output into log_buf.  If the caller didn't provide
+	 * appropriate log level tags, we insert them here
+	 */
+	for (p = printk_buf; *p; p++) {
+		if (log_level_unknown) {
+                        /* log_level_unknown signals the start of a new line */
+			if (printk_time) {
+				int loglev_char;
+				char tbuf[50], *tp;
+				unsigned tlen;
+				unsigned long long t;
+				unsigned long nanosec_rem;
+
+				/*
+				 * force the log level token to be
+				 * before the time output.
+				 */
+				if (p[0] == '<' && p[1] >='0' &&
+				   p[1] <= '7' && p[2] == '>') {
+					loglev_char = p[1];
+					p += 3;
+					printed_len += 3;
+				} else {
+					loglev_char = default_message_loglevel
+						+ '0';
+				}
+				t = sched_clock();
+				nanosec_rem = do_div(t, 1000000000);
+				tlen = sprintf(tbuf,
+						"<%c>[%5lu.%06lu] ",
+						loglev_char,
+						(unsigned long)t,
+						nanosec_rem/1000);
+
+				for (tp = tbuf; tp < tbuf + tlen; tp++)
+					emit_log_char(*tp);
+				printed_len += tlen - 3;
+			} else {
+				if (p[0] != '<' || p[1] < '0' ||
+				   p[1] > '7' || p[2] != '>') {
+					emit_log_char('<');
+					emit_log_char(default_message_loglevel
+						+ '0');
+					emit_log_char('>');
+				}
+				printed_len += 3;
+			}
+			log_level_unknown = 0;
+			if (!*p)
+				break;
+		}
+		emit_log_char(*p);
+		if (*p == '\n')
+			log_level_unknown = 1;
+	}
+
+	if (!cpu_online(smp_processor_id()) &&
+	    system_state != SYSTEM_RUNNING) {
+		/*
+		 * Some console drivers may assume that per-cpu resources have
+		 * been allocated.  So don't allow them to be called by this
+		 * CPU until it is officially up.  We shouldn't be calling into
+		 * random console drivers on a CPU which doesn't exist yet..
+		 */
+		spin_unlock_irqrestore(&logbuf_lock, flags);
+		goto out;
+	}
+	if (!down_trylock(&console_sem)) {
+		console_locked = 1;
+		/*
+		 * We own the drivers.  We can drop the spinlock and let
+		 * release_console_sem() print the text
+		 */
+		spin_unlock_irqrestore(&logbuf_lock, flags);
+		console_may_schedule = 0;
+		release_console_sem();
+	} else {
+		/*
+		 * Someone else owns the drivers.  We drop the spinlock, which
+		 * allows the semaphore holder to proceed and to call the
+		 * console drivers with the output which we just produced.
+		 */
+		spin_unlock_irqrestore(&logbuf_lock, flags);
+	}
+out:
+	return printed_len;
+}
+EXPORT_SYMBOL(printk);
+EXPORT_SYMBOL(vprintk);
+
+/**
+ * acquire_console_sem - lock the console system for exclusive use.
+ *
+ * Acquires a semaphore which guarantees that the caller has
+ * exclusive access to the console system and the console_drivers list.
+ *
+ * Can sleep, returns nothing.
+ */
+void acquire_console_sem(void)
+{
+	if (in_interrupt())
+		BUG();
+	down(&console_sem);
+	console_locked = 1;
+	console_may_schedule = 1;
+}
+EXPORT_SYMBOL(acquire_console_sem);
+
+int try_acquire_console_sem(void)
+{
+	if (down_trylock(&console_sem))
+		return -1;
+	console_locked = 1;
+	console_may_schedule = 0;
+	return 0;
+}
+EXPORT_SYMBOL(try_acquire_console_sem);
+
+int is_console_locked(void)
+{
+	return console_locked;
+}
+EXPORT_SYMBOL(is_console_locked);
+
+/**
+ * release_console_sem - unlock the console system
+ *
+ * Releases the semaphore which the caller holds on the console system
+ * and the console driver list.
+ *
+ * While the semaphore was held, console output may have been buffered
+ * by printk().  If this is the case, release_console_sem() emits
+ * the output prior to releasing the semaphore.
+ *
+ * If there is output waiting for klogd, we wake it up.
+ *
+ * release_console_sem() may be called from any context.
+ */
+void release_console_sem(void)
+{
+	unsigned long flags;
+	unsigned long _con_start, _log_end;
+	unsigned long wake_klogd = 0;
+
+	for ( ; ; ) {
+		spin_lock_irqsave(&logbuf_lock, flags);
+		wake_klogd |= log_start - log_end;
+		if (con_start == log_end)
+			break;			/* Nothing to print */
+		_con_start = con_start;
+		_log_end = log_end;
+		con_start = log_end;		/* Flush */
+		spin_unlock(&logbuf_lock);
+		call_console_drivers(_con_start, _log_end);
+		local_irq_restore(flags);
+	}
+	console_locked = 0;
+	console_may_schedule = 0;
+	up(&console_sem);
+	spin_unlock_irqrestore(&logbuf_lock, flags);
+	if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait))
+		wake_up_interruptible(&log_wait);
+}
+EXPORT_SYMBOL(release_console_sem);
+
+/** console_conditional_schedule - yield the CPU if required
+ *
+ * If the console code is currently allowed to sleep, and
+ * if this CPU should yield the CPU to another task, do
+ * so here.
+ *
+ * Must be called within acquire_console_sem().
+ */
+void __sched console_conditional_schedule(void)
+{
+	if (console_may_schedule)
+		cond_resched();
+}
+EXPORT_SYMBOL(console_conditional_schedule);
+
+void console_print(const char *s)
+{
+	printk(KERN_EMERG "%s", s);
+}
+EXPORT_SYMBOL(console_print);
+
+void console_unblank(void)
+{
+	struct console *c;
+
+	/*
+	 * console_unblank can no longer be called in interrupt context unless
+	 * oops_in_progress is set to 1..
+	 */
+	if (oops_in_progress) {
+		if (down_trylock(&console_sem) != 0)
+			return;
+	} else
+		acquire_console_sem();
+
+	console_locked = 1;
+	console_may_schedule = 0;
+	for (c = console_drivers; c != NULL; c = c->next)
+		if ((c->flags & CON_ENABLED) && c->unblank)
+			c->unblank();
+	release_console_sem();
+}
+EXPORT_SYMBOL(console_unblank);
+
+/*
+ * Return the console tty driver structure and its associated index
+ */
+struct tty_driver *console_device(int *index)
+{
+	struct console *c;
+	struct tty_driver *driver = NULL;
+
+	acquire_console_sem();
+	for (c = console_drivers; c != NULL; c = c->next) {
+		if (!c->device)
+			continue;
+		driver = c->device(c, index);
+		if (driver)
+			break;
+	}
+	release_console_sem();
+	return driver;
+}
+
+/*
+ * Prevent further output on the passed console device so that (for example)
+ * serial drivers can disable console output before suspending a port, and can
+ * re-enable output afterwards.
+ */
+void console_stop(struct console *console)
+{
+	acquire_console_sem();
+	console->flags &= ~CON_ENABLED;
+	release_console_sem();
+}
+EXPORT_SYMBOL(console_stop);
+
+void console_start(struct console *console)
+{
+	acquire_console_sem();
+	console->flags |= CON_ENABLED;
+	release_console_sem();
+}
+EXPORT_SYMBOL(console_start);
+
+/*
+ * The console driver calls this routine during kernel initialization
+ * to register the console printing procedure with printk() and to
+ * print any messages that were printed by the kernel before the
+ * console driver was initialized.
+ */
+void register_console(struct console * console)
+{
+	int     i;
+	unsigned long flags;
+
+	if (preferred_console < 0)
+		preferred_console = selected_console;
+
+	/*
+	 *	See if we want to use this console driver. If we
+	 *	didn't select a console we take the first one
+	 *	that registers here.
+	 */
+	if (preferred_console < 0) {
+		if (console->index < 0)
+			console->index = 0;
+		if (console->setup == NULL ||
+		    console->setup(console, NULL) == 0) {
+			console->flags |= CON_ENABLED | CON_CONSDEV;
+			preferred_console = 0;
+		}
+	}
+
+	/*
+	 *	See if this console matches one we selected on
+	 *	the command line.
+	 */
+	for(i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++) {
+		if (strcmp(console_cmdline[i].name, console->name) != 0)
+			continue;
+		if (console->index >= 0 &&
+		    console->index != console_cmdline[i].index)
+			continue;
+		if (console->index < 0)
+			console->index = console_cmdline[i].index;
+		if (console->setup &&
+		    console->setup(console, console_cmdline[i].options) != 0)
+			break;
+		console->flags |= CON_ENABLED;
+		console->index = console_cmdline[i].index;
+		if (i == preferred_console)
+			console->flags |= CON_CONSDEV;
+		break;
+	}
+
+	if (!(console->flags & CON_ENABLED))
+		return;
+
+	if (console_drivers && (console_drivers->flags & CON_BOOT)) {
+		unregister_console(console_drivers);
+		console->flags &= ~CON_PRINTBUFFER;
+	}
+
+	/*
+	 *	Put this console in the list - keep the
+	 *	preferred driver at the head of the list.
+	 */
+	acquire_console_sem();
+	if ((console->flags & CON_CONSDEV) || console_drivers == NULL) {
+		console->next = console_drivers;
+		console_drivers = console;
+	} else {
+		console->next = console_drivers->next;
+		console_drivers->next = console;
+	}
+	if (console->flags & CON_PRINTBUFFER) {
+		/*
+		 * release_console_sem() will print out the buffered messages
+		 * for us.
+		 */
+		spin_lock_irqsave(&logbuf_lock, flags);
+		con_start = log_start;
+		spin_unlock_irqrestore(&logbuf_lock, flags);
+	}
+	release_console_sem();
+}
+EXPORT_SYMBOL(register_console);
+
+int unregister_console(struct console * console)
+{
+        struct console *a,*b;
+	int res = 1;
+
+	acquire_console_sem();
+	if (console_drivers == console) {
+		console_drivers=console->next;
+		res = 0;
+	} else {
+		for (a=console_drivers->next, b=console_drivers ;
+		     a; b=a, a=b->next) {
+			if (a == console) {
+				b->next = a->next;
+				res = 0;
+				break;
+			}  
+		}
+	}
+	
+	/* If last console is removed, we re-enable picking the first
+	 * one that gets registered. Without that, pmac early boot console
+	 * would prevent fbcon from taking over.
+	 */
+	if (console_drivers == NULL)
+		preferred_console = selected_console;
+		
+
+	release_console_sem();
+	return res;
+}
+EXPORT_SYMBOL(unregister_console);
+	
+/**
+ * tty_write_message - write a message to a certain tty, not just the console.
+ *
+ * This is used for messages that need to be redirected to a specific tty.
+ * We don't put it into the syslog queue right now maybe in the future if
+ * really needed.
+ */
+void tty_write_message(struct tty_struct *tty, char *msg)
+{
+	if (tty && tty->driver->write)
+		tty->driver->write(tty, msg, strlen(msg));
+	return;
+}
+
+/*
+ * printk rate limiting, lifted from the networking subsystem.
+ *
+ * This enforces a rate limit: not more than one kernel message
+ * every printk_ratelimit_jiffies to make a denial-of-service
+ * attack impossible.
+ */
+int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst)
+{
+	static DEFINE_SPINLOCK(ratelimit_lock);
+	static unsigned long toks = 10*5*HZ;
+	static unsigned long last_msg;
+	static int missed;
+	unsigned long flags;
+	unsigned long now = jiffies;
+
+	spin_lock_irqsave(&ratelimit_lock, flags);
+	toks += now - last_msg;
+	last_msg = now;
+	if (toks > (ratelimit_burst * ratelimit_jiffies))
+		toks = ratelimit_burst * ratelimit_jiffies;
+	if (toks >= ratelimit_jiffies) {
+		int lost = missed;
+		missed = 0;
+		toks -= ratelimit_jiffies;
+		spin_unlock_irqrestore(&ratelimit_lock, flags);
+		if (lost)
+			printk(KERN_WARNING "printk: %d messages suppressed.\n", lost);
+		return 1;
+	}
+	missed++;
+	spin_unlock_irqrestore(&ratelimit_lock, flags);
+	return 0;
+}
+EXPORT_SYMBOL(__printk_ratelimit);
+
+/* minimum time in jiffies between messages */
+int printk_ratelimit_jiffies = 5*HZ;
+
+/* number of messages we send before ratelimiting */
+int printk_ratelimit_burst = 10;
+
+int printk_ratelimit(void)
+{
+	return __printk_ratelimit(printk_ratelimit_jiffies,
+				printk_ratelimit_burst);
+}
+EXPORT_SYMBOL(printk_ratelimit);