* 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>
+ * 01Mar01 Andrew Morton
*/
#include <linux/kernel.h>
#include <linux/security.h>
#include <linux/bootmem.h>
#include <linux/syscalls.h>
+#include <linux/kexec.h>
#include <asm/uaccess.h>
* driver system.
*/
static DECLARE_MUTEX(console_sem);
-static DECLARE_MUTEX(secondary_console_sem);
struct console *console_drivers;
EXPORT_SYMBOL_GPL(console_drivers);
static int log_buf_len = __LOG_BUF_LEN;
static unsigned logged_chars; /* Number of chars produced since last read+clear operation */
+#ifdef CONFIG_KEXEC
+/*
+ * This appends the listed symbols to /proc/vmcoreinfo
+ *
+ * /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to
+ * obtain access to symbols that are otherwise very difficult to locate. These
+ * symbols are specifically used so that utilities can access and extract the
+ * dmesg log from a vmcore file after a crash.
+ */
+void log_buf_kexec_setup(void)
+{
+ VMCOREINFO_SYMBOL(log_buf);
+ VMCOREINFO_SYMBOL(log_end);
+ VMCOREINFO_SYMBOL(log_buf_len);
+ VMCOREINFO_SYMBOL(logged_chars);
+}
+#endif
+
static int __init log_buf_len_setup(char *str)
{
unsigned size = memparse(str, &str);
#endif
/*
- * Return the number of unread characters in the log buffer.
- */
-static 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;
-}
-
-/*
* Commands to do_syslog:
*
* 0 -- Close the log. Currently a NOP.
return error;
}
-asmlinkage long sys_syslog(int type, char __user *buf, int len)
+SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
{
return do_syslog(type, buf, len);
}
* @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
*
* See also:
* printf(3)
+ *
+ * See the vsnprintf() documentation for format string extensions over C99.
*/
asmlinkage int printk(const char *fmt, ...)
static const char recursion_bug_msg [] =
KERN_CRIT "BUG: recent printk recursion!\n";
static int recursion_bug;
- static int new_text_line = 1;
+static int new_text_line = 1;
static char printk_buf[1024];
asmlinkage int vprintk(const char *fmt, va_list args)
if (recursion_bug) {
recursion_bug = 0;
strcpy(printk_buf, recursion_bug_msg);
- printed_len = sizeof(recursion_bug_msg);
+ printed_len = strlen(recursion_bug_msg);
}
/* Emit the output into the temporary buffer */
printed_len += vscnprintf(printk_buf + printed_len,
#else
-asmlinkage long sys_syslog(int type, char __user *buf, int len)
-{
- return -ENOSYS;
-}
-
static void call_console_drivers(unsigned start, unsigned end)
{
}
printk("Suspending console(s) (use no_console_suspend to debug)\n");
acquire_console_sem();
console_suspended = 1;
+ up(&console_sem);
}
void resume_console(void)
{
if (!console_suspend_enabled)
return;
+ down(&console_sem);
console_suspended = 0;
release_console_sem();
}
void acquire_console_sem(void)
{
BUG_ON(in_interrupt());
- if (console_suspended) {
- down(&secondary_console_sem);
- return;
- }
down(&console_sem);
+ if (console_suspended)
+ return;
console_locked = 1;
console_may_schedule = 1;
}
{
if (down_trylock(&console_sem))
return -1;
+ if (console_suspended) {
+ up(&console_sem);
+ return -1;
+ }
console_locked = 1;
console_may_schedule = 0;
return 0;
return console_locked;
}
-void wake_up_klogd(void)
+static DEFINE_PER_CPU(int, printk_pending);
+
+void printk_tick(void)
{
- if (!oops_in_progress && waitqueue_active(&log_wait))
+ if (__get_cpu_var(printk_pending)) {
+ __get_cpu_var(printk_pending) = 0;
wake_up_interruptible(&log_wait);
+ }
+}
+
+int printk_needs_cpu(int cpu)
+{
+ return per_cpu(printk_pending, cpu);
+}
+
+void wake_up_klogd(void)
+{
+ if (waitqueue_active(&log_wait))
+ __raw_get_cpu_var(printk_pending) = 1;
}
/**
unsigned wake_klogd = 0;
if (console_suspended) {
- up(&secondary_console_sem);
+ up(&console_sem);
return;
}
}
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->ops->write)
- tty->ops->write(tty, msg, strlen(msg));
- return;
-}
-
#if defined CONFIG_PRINTK
+
/*
* 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.
+ * This enforces a rate limit: not more than 10 kernel messages
+ * every 5s to make a denial-of-service attack impossible.
*/
-int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst)
-{
- return __ratelimit(ratelimit_jiffies, ratelimit_burst);
-}
-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;
+DEFINE_RATELIMIT_STATE(printk_ratelimit_state, 5 * HZ, 10);
int printk_ratelimit(void)
{
- return __printk_ratelimit(printk_ratelimit_jiffies,
- printk_ratelimit_burst);
+ return __ratelimit(&printk_ratelimit_state);
}
EXPORT_SYMBOL(printk_ratelimit);
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);
+ if (*caller_jiffies == 0
+ || !time_in_range(jiffies, *caller_jiffies,
+ *caller_jiffies
+ + msecs_to_jiffies(interval_msecs))) {
+ *caller_jiffies = jiffies;
return true;
}
return false;