mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 19:29:37 +00:00
![Ingo Molnar](/assets/img/avatar_default.png)
revert 19ef930927
.
Kevin Winchester reported a lockup during X startup an bisected
it to this commit.
Reported-by: Kevin Winchester <kjwinchester@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
1329 lines
32 KiB
C
1329 lines
32 KiB
C
/*
|
|
* 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
|
|
* manfred@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/console.h>
|
|
#include <linux/init.h>
|
|
#include <linux/jiffies.h>
|
|
#include <linux/nmi.h>
|
|
#include <linux/module.h>
|
|
#include <linux/moduleparam.h>
|
|
#include <linux/interrupt.h> /* For in_interrupt() */
|
|
#include <linux/delay.h>
|
|
#include <linux/smp.h>
|
|
#include <linux/security.h>
|
|
#include <linux/bootmem.h>
|
|
#include <linux/syscalls.h>
|
|
#include <linux/jiffies.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 */
|
|
};
|
|
|
|
/*
|
|
* Low level 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);
|
|
static DECLARE_MUTEX(secondary_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, console_suspended;
|
|
|
|
/*
|
|
* 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);
|
|
|
|
#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 */
|
|
|
|
/*
|
|
* 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;
|
|
|
|
#ifdef CONFIG_PRINTK
|
|
|
|
static char __log_buf[__LOG_BUF_LEN];
|
|
static char *log_buf = __log_buf;
|
|
static int log_buf_len = __LOG_BUF_LEN;
|
|
static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */
|
|
|
|
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(KERN_WARNING "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(KERN_NOTICE "log_buf_len: %d\n", log_buf_len);
|
|
}
|
|
out:
|
|
return 1;
|
|
}
|
|
|
|
__setup("log_buf_len=", log_buf_len_setup);
|
|
|
|
#ifdef CONFIG_BOOT_PRINTK_DELAY
|
|
|
|
static unsigned int boot_delay; /* msecs delay after each printk during bootup */
|
|
static unsigned long long printk_delay_msec; /* per msec, based on boot_delay */
|
|
|
|
static int __init boot_delay_setup(char *str)
|
|
{
|
|
unsigned long lpj;
|
|
unsigned long long loops_per_msec;
|
|
|
|
lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */
|
|
loops_per_msec = (unsigned long long)lpj / 1000 * HZ;
|
|
|
|
get_option(&str, &boot_delay);
|
|
if (boot_delay > 10 * 1000)
|
|
boot_delay = 0;
|
|
|
|
printk_delay_msec = loops_per_msec;
|
|
printk(KERN_DEBUG "boot_delay: %u, preset_lpj: %ld, lpj: %lu, "
|
|
"HZ: %d, printk_delay_msec: %llu\n",
|
|
boot_delay, preset_lpj, lpj, HZ, printk_delay_msec);
|
|
return 1;
|
|
}
|
|
__setup("boot_delay=", boot_delay_setup);
|
|
|
|
static void boot_delay_msec(void)
|
|
{
|
|
unsigned long long k;
|
|
unsigned long timeout;
|
|
|
|
if (boot_delay == 0 || system_state != SYSTEM_BOOTING)
|
|
return;
|
|
|
|
k = (unsigned long long)printk_delay_msec * boot_delay;
|
|
|
|
timeout = jiffies + msecs_to_jiffies(boot_delay);
|
|
while (k) {
|
|
k--;
|
|
cpu_relax();
|
|
/*
|
|
* use (volatile) jiffies to prevent
|
|
* compiler reduction; loop termination via jiffies
|
|
* is secondary and may or may not happen.
|
|
*/
|
|
if (time_after(jiffies, timeout))
|
|
break;
|
|
touch_nmi_watchdog();
|
|
}
|
|
}
|
|
#else
|
|
static inline void boot_delay_msec(void)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Return the number of unread characters in the log buffer.
|
|
*/
|
|
int log_buf_get_len(void)
|
|
{
|
|
return logged_chars;
|
|
}
|
|
|
|
/*
|
|
* Copy a range of characters from the log buffer.
|
|
*/
|
|
int log_buf_copy(char *dest, int idx, int len)
|
|
{
|
|
int ret, max;
|
|
bool took_lock = false;
|
|
|
|
if (!oops_in_progress) {
|
|
spin_lock_irq(&logbuf_lock);
|
|
took_lock = true;
|
|
}
|
|
|
|
max = log_buf_get_len();
|
|
if (idx < 0 || idx >= max) {
|
|
ret = -1;
|
|
} else {
|
|
if (len > max)
|
|
len = max;
|
|
ret = len;
|
|
idx += (log_end - max);
|
|
while (len-- > 0)
|
|
dest[len] = LOG_BUF(idx + len);
|
|
}
|
|
|
|
if (took_lock)
|
|
spin_unlock_irq(&logbuf_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Extract a single character from the log buffer.
|
|
*/
|
|
int log_buf_read(int idx)
|
|
{
|
|
char ret;
|
|
|
|
if (log_buf_copy(&ret, idx, 1) == 1)
|
|
return ret;
|
|
else
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* 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 &&
|
|
(cpu_online(smp_processor_id()) ||
|
|
(con->flags & CON_ANYTIME)))
|
|
con->write(con, &LOG_BUF(start), end - start);
|
|
}
|
|
}
|
|
|
|
static int __read_mostly ignore_loglevel;
|
|
|
|
static int __init ignore_loglevel_setup(char *str)
|
|
{
|
|
ignore_loglevel = 1;
|
|
printk(KERN_INFO "debug: ignoring loglevel setting.\n");
|
|
|
|
return 1;
|
|
}
|
|
|
|
__setup("ignore_loglevel", ignore_loglevel_setup);
|
|
|
|
/*
|
|
* 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 || ignore_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;
|
|
|
|
BUG_ON(((long)(start - end)) > 0);
|
|
|
|
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
|
|
module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
|
|
|
|
static int __init printk_time_setup(char *str)
|
|
{
|
|
if (*str)
|
|
return 0;
|
|
printk_time = 1;
|
|
printk(KERN_NOTICE "The 'time' option is deprecated and "
|
|
"is scheduled for removal in early 2008\n");
|
|
printk(KERN_NOTICE "Use 'printk.time=<value>' instead\n");
|
|
return 1;
|
|
}
|
|
|
|
__setup("time", printk_time_setup);
|
|
|
|
/* Check if we have any console registered that can be called early in boot. */
|
|
static int have_callable_console(void)
|
|
{
|
|
struct console *con;
|
|
|
|
for (con = console_drivers; con; con = con->next)
|
|
if (con->flags & CON_ANYTIME)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* printk - print a kernel message
|
|
* @fmt: format string
|
|
*
|
|
* This is printk(). It can be called from any context. We want it to work.
|
|
* Be aware of the fact that if oops_in_progress is not set, we might try to
|
|
* wake klogd up which could deadlock on runqueue lock if printk() is called
|
|
* from scheduler code.
|
|
*
|
|
* 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.
|
|
*
|
|
* See also:
|
|
* printf(3)
|
|
*/
|
|
|
|
asmlinkage int printk(const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
int r;
|
|
|
|
va_start(args, fmt);
|
|
r = vprintk(fmt, args);
|
|
va_end(args);
|
|
|
|
return r;
|
|
}
|
|
|
|
/* cpu currently holding logbuf_lock */
|
|
static volatile unsigned int printk_cpu = UINT_MAX;
|
|
|
|
const char printk_recursion_bug_msg [] =
|
|
KERN_CRIT "BUG: recent printk recursion!\n";
|
|
static int printk_recursion_bug;
|
|
|
|
asmlinkage int vprintk(const char *fmt, va_list args)
|
|
{
|
|
static int log_level_unknown = 1;
|
|
static char printk_buf[1024];
|
|
|
|
unsigned long flags;
|
|
int printed_len = 0;
|
|
int this_cpu;
|
|
char *p;
|
|
|
|
boot_delay_msec();
|
|
|
|
preempt_disable();
|
|
/* This stops the holder of console_sem just where we want him */
|
|
raw_local_irq_save(flags);
|
|
this_cpu = smp_processor_id();
|
|
|
|
/*
|
|
* Ouch, printk recursed into itself!
|
|
*/
|
|
if (unlikely(printk_cpu == this_cpu)) {
|
|
/*
|
|
* If a crash is occurring during printk() on this CPU,
|
|
* then try to get the crash message out but make sure
|
|
* we can't deadlock. Otherwise just return to avoid the
|
|
* recursion and return - but flag the recursion so that
|
|
* it can be printed at the next appropriate moment:
|
|
*/
|
|
if (!oops_in_progress) {
|
|
printk_recursion_bug = 1;
|
|
goto out_restore_irqs;
|
|
}
|
|
zap_locks();
|
|
}
|
|
|
|
lockdep_off();
|
|
spin_lock(&logbuf_lock);
|
|
printk_cpu = this_cpu;
|
|
|
|
if (printk_recursion_bug) {
|
|
printk_recursion_bug = 0;
|
|
strcpy(printk_buf, printk_recursion_bug_msg);
|
|
printed_len = sizeof(printk_recursion_bug_msg);
|
|
}
|
|
/* Emit the output into the temporary buffer */
|
|
printed_len += vscnprintf(printk_buf + printed_len,
|
|
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 = cpu_clock(printk_cpu);
|
|
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;
|
|
} 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 (!down_trylock(&console_sem)) {
|
|
/*
|
|
* We own the drivers. We can drop the spinlock and
|
|
* let release_console_sem() print the text, maybe ...
|
|
*/
|
|
console_locked = 1;
|
|
printk_cpu = UINT_MAX;
|
|
spin_unlock(&logbuf_lock);
|
|
|
|
/*
|
|
* Console drivers may assume that per-cpu resources have
|
|
* been allocated. So unless they're explicitly marked as
|
|
* being able to cope (CON_ANYTIME) don't call them until
|
|
* this CPU is officially up.
|
|
*/
|
|
if (cpu_online(smp_processor_id()) || have_callable_console()) {
|
|
console_may_schedule = 0;
|
|
release_console_sem();
|
|
} else {
|
|
/* Release by hand to avoid flushing the buffer. */
|
|
console_locked = 0;
|
|
up(&console_sem);
|
|
}
|
|
lockdep_on();
|
|
raw_local_irq_restore(flags);
|
|
} 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.
|
|
*/
|
|
printk_cpu = UINT_MAX;
|
|
spin_unlock(&logbuf_lock);
|
|
lockdep_on();
|
|
out_restore_irqs:
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
|
|
preempt_enable();
|
|
return printed_len;
|
|
}
|
|
EXPORT_SYMBOL(printk);
|
|
EXPORT_SYMBOL(vprintk);
|
|
|
|
#else
|
|
|
|
asmlinkage long sys_syslog(int type, char __user *buf, int len)
|
|
{
|
|
return -ENOSYS;
|
|
}
|
|
|
|
static void call_console_drivers(unsigned long start, unsigned long end)
|
|
{
|
|
}
|
|
|
|
#endif
|
|
|
|
/*
|
|
* Set up a list of consoles. Called from init/main.c
|
|
*/
|
|
static int __init console_setup(char *str)
|
|
{
|
|
char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
|
|
char *s, *options;
|
|
int idx;
|
|
|
|
/*
|
|
* Decode str into name, index, options.
|
|
*/
|
|
if (str[0] >= '0' && str[0] <= '9') {
|
|
strcpy(buf, "ttyS");
|
|
strncpy(buf + 4, str, sizeof(buf) - 5);
|
|
} else {
|
|
strncpy(buf, str, sizeof(buf) - 1);
|
|
}
|
|
buf[sizeof(buf) - 1] = 0;
|
|
if ((options = strchr(str, ',')) != NULL)
|
|
*(options++) = 0;
|
|
#ifdef __sparc__
|
|
if (!strcmp(str, "ttya"))
|
|
strcpy(buf, "ttyS0");
|
|
if (!strcmp(str, "ttyb"))
|
|
strcpy(buf, "ttyS1");
|
|
#endif
|
|
for (s = buf; *s; s++)
|
|
if ((*s >= '0' && *s <= '9') || *s == ',')
|
|
break;
|
|
idx = simple_strtoul(s, NULL, 10);
|
|
*s = 0;
|
|
|
|
add_preferred_console(buf, idx, options);
|
|
return 1;
|
|
}
|
|
__setup("console=", console_setup);
|
|
|
|
/**
|
|
* add_preferred_console - add a device to the list of preferred consoles.
|
|
* @name: device name
|
|
* @idx: device index
|
|
* @options: options for this console
|
|
*
|
|
* 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 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;
|
|
}
|
|
|
|
int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
|
|
{
|
|
struct console_cmdline *c;
|
|
int i;
|
|
|
|
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) {
|
|
c = &console_cmdline[i];
|
|
memcpy(c->name, name_new, sizeof(c->name));
|
|
c->name[sizeof(c->name) - 1] = 0;
|
|
c->options = options;
|
|
c->index = idx_new;
|
|
return i;
|
|
}
|
|
/* not found */
|
|
return -1;
|
|
}
|
|
|
|
int console_suspend_enabled = 1;
|
|
EXPORT_SYMBOL(console_suspend_enabled);
|
|
|
|
static int __init console_suspend_disable(char *str)
|
|
{
|
|
console_suspend_enabled = 0;
|
|
return 1;
|
|
}
|
|
__setup("no_console_suspend", console_suspend_disable);
|
|
|
|
/**
|
|
* suspend_console - suspend the console subsystem
|
|
*
|
|
* This disables printk() while we go into suspend states
|
|
*/
|
|
void suspend_console(void)
|
|
{
|
|
if (!console_suspend_enabled)
|
|
return;
|
|
printk("Suspending console(s)\n");
|
|
acquire_console_sem();
|
|
console_suspended = 1;
|
|
}
|
|
|
|
void resume_console(void)
|
|
{
|
|
if (!console_suspend_enabled)
|
|
return;
|
|
console_suspended = 0;
|
|
release_console_sem();
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
BUG_ON(in_interrupt());
|
|
if (console_suspended) {
|
|
down(&secondary_console_sem);
|
|
return;
|
|
}
|
|
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;
|
|
}
|
|
|
|
void wake_up_klogd(void)
|
|
{
|
|
if (!oops_in_progress && waitqueue_active(&log_wait))
|
|
wake_up_interruptible(&log_wait);
|
|
}
|
|
|
|
/**
|
|
* 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;
|
|
|
|
if (console_suspended) {
|
|
up(&secondary_console_sem);
|
|
return;
|
|
}
|
|
|
|
console_may_schedule = 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;
|
|
up(&console_sem);
|
|
spin_unlock_irqrestore(&logbuf_lock, flags);
|
|
if (wake_klogd)
|
|
wake_up_klogd();
|
|
}
|
|
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();
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
struct console *bootconsole = NULL;
|
|
|
|
if (console_drivers) {
|
|
if (console->flags & CON_BOOT)
|
|
return;
|
|
if (console_drivers->flags & CON_BOOT)
|
|
bootconsole = console_drivers;
|
|
}
|
|
|
|
if (preferred_console < 0 || bootconsole || !console_drivers)
|
|
preferred_console = selected_console;
|
|
|
|
if (console->early_setup)
|
|
console->early_setup();
|
|
|
|
/*
|
|
* 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 == selected_console) {
|
|
console->flags |= CON_CONSDEV;
|
|
preferred_console = selected_console;
|
|
}
|
|
break;
|
|
}
|
|
|
|
if (!(console->flags & CON_ENABLED))
|
|
return;
|
|
|
|
if (bootconsole && (console->flags & CON_CONSDEV)) {
|
|
printk(KERN_INFO "console handover: boot [%s%d] -> real [%s%d]\n",
|
|
bootconsole->name, bootconsole->index,
|
|
console->name, console->index);
|
|
unregister_console(bootconsole);
|
|
console->flags &= ~CON_PRINTBUFFER;
|
|
} else {
|
|
printk(KERN_INFO "console [%s%d] enabled\n",
|
|
console->name, console->index);
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
if (console->next)
|
|
console->next->flags &= ~CON_CONSDEV;
|
|
} 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 if (console_drivers) {
|
|
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 this isn't the last console and it has CON_CONSDEV set, we
|
|
* need to set it on the next preferred console.
|
|
*/
|
|
if (console_drivers != NULL && console->flags & CON_CONSDEV)
|
|
console_drivers->flags |= CON_CONSDEV;
|
|
|
|
release_console_sem();
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(unregister_console);
|
|
|
|
static int __init disable_boot_consoles(void)
|
|
{
|
|
if (console_drivers != NULL) {
|
|
if (console_drivers->flags & CON_BOOT) {
|
|
printk(KERN_INFO "turn off boot console %s%d\n",
|
|
console_drivers->name, console_drivers->index);
|
|
return unregister_console(console_drivers);
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
late_initcall(disable_boot_consoles);
|
|
|
|
/**
|
|
* tty_write_message - write a message to a certain tty, not just the console.
|
|
* @tty: the destination tty_struct
|
|
* @msg: the message to write
|
|
*
|
|
* 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);
|
|
|
|
/**
|
|
* printk_timed_ratelimit - caller-controlled printk ratelimiting
|
|
* @caller_jiffies: pointer to caller's state
|
|
* @interval_msecs: minimum interval between prints
|
|
*
|
|
* printk_timed_ratelimit() returns true if more than @interval_msecs
|
|
* milliseconds have elapsed since the last time printk_timed_ratelimit()
|
|
* returned true.
|
|
*/
|
|
bool printk_timed_ratelimit(unsigned long *caller_jiffies,
|
|
unsigned int interval_msecs)
|
|
{
|
|
if (*caller_jiffies == 0 || time_after(jiffies, *caller_jiffies)) {
|
|
*caller_jiffies = jiffies + msecs_to_jiffies(interval_msecs);
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
EXPORT_SYMBOL(printk_timed_ratelimit);
|