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![Andrew Morton](/assets/img/avatar_default.png)
printk_ratelimit() has global state which makes it not useful for callers which wish to perform ratelimiting at a particular frequency. Add a printk_timed_ratelimit() which utilises caller-provided state storage to permit more flexibility. This function can in fact be used for things other than printk ratelimiting and is perhaps poorly named. Cc: Ulrich Drepper <drepper@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1124 lines
28 KiB
C
1124 lines
28 KiB
C
/*
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* linux/kernel/printk.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* Modified to make sys_syslog() more flexible: added commands to
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* return the last 4k of kernel messages, regardless of whether
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* they've been read or not. Added option to suppress kernel printk's
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* to the console. Added hook for sending the console messages
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* elsewhere, in preparation for a serial line console (someday).
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* Ted Ts'o, 2/11/93.
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* Modified for sysctl support, 1/8/97, Chris Horn.
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* Fixed SMP synchronization, 08/08/99, Manfred Spraul
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* manfred@colorfullife.com
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* Rewrote bits to get rid of console_lock
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* 01Mar01 Andrew Morton <andrewm@uow.edu.au>
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/tty.h>
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#include <linux/tty_driver.h>
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#include <linux/smp_lock.h>
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#include <linux/console.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/interrupt.h> /* For in_interrupt() */
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#include <linux/delay.h>
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#include <linux/smp.h>
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#include <linux/security.h>
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#include <linux/bootmem.h>
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#include <linux/syscalls.h>
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#include <linux/jiffies.h>
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#include <asm/uaccess.h>
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#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
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/* printk's without a loglevel use this.. */
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#define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */
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/* We show everything that is MORE important than this.. */
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#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
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#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
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DECLARE_WAIT_QUEUE_HEAD(log_wait);
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int console_printk[4] = {
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DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
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DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */
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MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */
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DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
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};
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EXPORT_UNUSED_SYMBOL(console_printk); /* June 2006 */
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/*
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* Low lever drivers may need that to know if they can schedule in
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* their unblank() callback or not. So let's export it.
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*/
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int oops_in_progress;
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EXPORT_SYMBOL(oops_in_progress);
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/*
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* console_sem protects the console_drivers list, and also
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* provides serialisation for access to the entire console
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* driver system.
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*/
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static DECLARE_MUTEX(console_sem);
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static DECLARE_MUTEX(secondary_console_sem);
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struct console *console_drivers;
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/*
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* This is used for debugging the mess that is the VT code by
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* keeping track if we have the console semaphore held. It's
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* definitely not the perfect debug tool (we don't know if _WE_
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* hold it are racing, but it helps tracking those weird code
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* path in the console code where we end up in places I want
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* locked without the console sempahore held
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*/
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static int console_locked, console_suspended;
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/*
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* logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars
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* It is also used in interesting ways to provide interlocking in
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* release_console_sem().
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*/
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static DEFINE_SPINLOCK(logbuf_lock);
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#define LOG_BUF_MASK (log_buf_len-1)
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#define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK])
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/*
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* The indices into log_buf are not constrained to log_buf_len - they
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* must be masked before subscripting
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*/
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static unsigned long log_start; /* Index into log_buf: next char to be read by syslog() */
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static unsigned long con_start; /* Index into log_buf: next char to be sent to consoles */
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static unsigned long log_end; /* Index into log_buf: most-recently-written-char + 1 */
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/*
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* Array of consoles built from command line options (console=)
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*/
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struct console_cmdline
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{
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char name[8]; /* Name of the driver */
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int index; /* Minor dev. to use */
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char *options; /* Options for the driver */
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};
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#define MAX_CMDLINECONSOLES 8
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static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
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static int selected_console = -1;
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static int preferred_console = -1;
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/* Flag: console code may call schedule() */
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static int console_may_schedule;
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#ifdef CONFIG_PRINTK
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static char __log_buf[__LOG_BUF_LEN];
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static char *log_buf = __log_buf;
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static int log_buf_len = __LOG_BUF_LEN;
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static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */
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static int __init log_buf_len_setup(char *str)
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{
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unsigned long size = memparse(str, &str);
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unsigned long flags;
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if (size)
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size = roundup_pow_of_two(size);
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if (size > log_buf_len) {
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unsigned long start, dest_idx, offset;
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char *new_log_buf;
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new_log_buf = alloc_bootmem(size);
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if (!new_log_buf) {
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printk(KERN_WARNING "log_buf_len: allocation failed\n");
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goto out;
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}
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spin_lock_irqsave(&logbuf_lock, flags);
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log_buf_len = size;
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log_buf = new_log_buf;
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offset = start = min(con_start, log_start);
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dest_idx = 0;
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while (start != log_end) {
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log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)];
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start++;
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dest_idx++;
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}
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log_start -= offset;
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con_start -= offset;
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log_end -= offset;
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spin_unlock_irqrestore(&logbuf_lock, flags);
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printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len);
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}
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out:
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return 1;
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}
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__setup("log_buf_len=", log_buf_len_setup);
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/*
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* Commands to do_syslog:
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*
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* 0 -- Close the log. Currently a NOP.
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* 1 -- Open the log. Currently a NOP.
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* 2 -- Read from the log.
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* 3 -- Read all messages remaining in the ring buffer.
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* 4 -- Read and clear all messages remaining in the ring buffer
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* 5 -- Clear ring buffer.
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* 6 -- Disable printk's to console
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* 7 -- Enable printk's to console
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* 8 -- Set level of messages printed to console
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* 9 -- Return number of unread characters in the log buffer
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* 10 -- Return size of the log buffer
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*/
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int do_syslog(int type, char __user *buf, int len)
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{
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unsigned long i, j, limit, count;
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int do_clear = 0;
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char c;
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int error = 0;
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error = security_syslog(type);
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if (error)
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return error;
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switch (type) {
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case 0: /* Close log */
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break;
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case 1: /* Open log */
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break;
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case 2: /* Read from log */
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error = -EINVAL;
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if (!buf || len < 0)
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goto out;
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error = 0;
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if (!len)
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goto out;
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if (!access_ok(VERIFY_WRITE, buf, len)) {
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error = -EFAULT;
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goto out;
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}
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error = wait_event_interruptible(log_wait,
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(log_start - log_end));
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if (error)
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goto out;
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i = 0;
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spin_lock_irq(&logbuf_lock);
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while (!error && (log_start != log_end) && i < len) {
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c = LOG_BUF(log_start);
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log_start++;
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spin_unlock_irq(&logbuf_lock);
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error = __put_user(c,buf);
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buf++;
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i++;
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cond_resched();
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spin_lock_irq(&logbuf_lock);
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}
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spin_unlock_irq(&logbuf_lock);
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if (!error)
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error = i;
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break;
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case 4: /* Read/clear last kernel messages */
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do_clear = 1;
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/* FALL THRU */
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case 3: /* Read last kernel messages */
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error = -EINVAL;
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if (!buf || len < 0)
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goto out;
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error = 0;
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if (!len)
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goto out;
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if (!access_ok(VERIFY_WRITE, buf, len)) {
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error = -EFAULT;
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goto out;
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}
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count = len;
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if (count > log_buf_len)
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count = log_buf_len;
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spin_lock_irq(&logbuf_lock);
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if (count > logged_chars)
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count = logged_chars;
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if (do_clear)
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logged_chars = 0;
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limit = log_end;
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/*
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* __put_user() could sleep, and while we sleep
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* printk() could overwrite the messages
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* we try to copy to user space. Therefore
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* the messages are copied in reverse. <manfreds>
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*/
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for (i = 0; i < count && !error; i++) {
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j = limit-1-i;
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if (j + log_buf_len < log_end)
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break;
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c = LOG_BUF(j);
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spin_unlock_irq(&logbuf_lock);
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error = __put_user(c,&buf[count-1-i]);
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cond_resched();
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spin_lock_irq(&logbuf_lock);
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}
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spin_unlock_irq(&logbuf_lock);
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if (error)
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break;
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error = i;
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if (i != count) {
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int offset = count-error;
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/* buffer overflow during copy, correct user buffer. */
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for (i = 0; i < error; i++) {
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if (__get_user(c,&buf[i+offset]) ||
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__put_user(c,&buf[i])) {
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error = -EFAULT;
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break;
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}
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cond_resched();
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}
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}
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break;
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case 5: /* Clear ring buffer */
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logged_chars = 0;
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break;
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case 6: /* Disable logging to console */
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console_loglevel = minimum_console_loglevel;
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break;
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case 7: /* Enable logging to console */
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console_loglevel = default_console_loglevel;
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break;
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case 8: /* Set level of messages printed to console */
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error = -EINVAL;
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if (len < 1 || len > 8)
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goto out;
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if (len < minimum_console_loglevel)
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len = minimum_console_loglevel;
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console_loglevel = len;
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error = 0;
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break;
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case 9: /* Number of chars in the log buffer */
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error = log_end - log_start;
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break;
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case 10: /* Size of the log buffer */
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error = log_buf_len;
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break;
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default:
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error = -EINVAL;
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break;
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}
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out:
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return error;
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}
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asmlinkage long sys_syslog(int type, char __user *buf, int len)
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{
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return do_syslog(type, buf, len);
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}
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/*
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* Call the console drivers on a range of log_buf
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*/
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static void __call_console_drivers(unsigned long start, unsigned long end)
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{
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struct console *con;
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for (con = console_drivers; con; con = con->next) {
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if ((con->flags & CON_ENABLED) && con->write &&
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(cpu_online(smp_processor_id()) ||
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(con->flags & CON_ANYTIME)))
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con->write(con, &LOG_BUF(start), end - start);
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}
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}
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/*
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* Write out chars from start to end - 1 inclusive
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*/
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static void _call_console_drivers(unsigned long start,
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unsigned long end, int msg_log_level)
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{
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if (msg_log_level < console_loglevel &&
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console_drivers && start != end) {
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if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) {
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/* wrapped write */
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__call_console_drivers(start & LOG_BUF_MASK,
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log_buf_len);
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__call_console_drivers(0, end & LOG_BUF_MASK);
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} else {
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__call_console_drivers(start, end);
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}
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}
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}
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/*
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* Call the console drivers, asking them to write out
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* log_buf[start] to log_buf[end - 1].
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* The console_sem must be held.
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*/
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static void call_console_drivers(unsigned long start, unsigned long end)
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{
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unsigned long cur_index, start_print;
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static int msg_level = -1;
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BUG_ON(((long)(start - end)) > 0);
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cur_index = start;
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start_print = start;
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while (cur_index != end) {
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if (msg_level < 0 && ((end - cur_index) > 2) &&
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LOG_BUF(cur_index + 0) == '<' &&
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LOG_BUF(cur_index + 1) >= '0' &&
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LOG_BUF(cur_index + 1) <= '7' &&
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LOG_BUF(cur_index + 2) == '>') {
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msg_level = LOG_BUF(cur_index + 1) - '0';
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cur_index += 3;
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start_print = cur_index;
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}
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while (cur_index != end) {
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char c = LOG_BUF(cur_index);
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cur_index++;
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if (c == '\n') {
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if (msg_level < 0) {
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/*
|
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* printk() has already given us loglevel tags in
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* the buffer. This code is here in case the
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* log buffer has wrapped right round and scribbled
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* on those tags
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*/
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msg_level = default_message_loglevel;
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}
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_call_console_drivers(start_print, cur_index, msg_level);
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msg_level = -1;
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start_print = cur_index;
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break;
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}
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}
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}
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_call_console_drivers(start_print, end, msg_level);
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}
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|
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static void emit_log_char(char c)
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{
|
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LOG_BUF(log_end) = c;
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log_end++;
|
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if (log_end - log_start > log_buf_len)
|
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log_start = log_end - log_buf_len;
|
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if (log_end - con_start > log_buf_len)
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con_start = log_end - log_buf_len;
|
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if (logged_chars < log_buf_len)
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logged_chars++;
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}
|
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|
|
/*
|
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* Zap console related locks when oopsing. Only zap at most once
|
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* every 10 seconds, to leave time for slow consoles to print a
|
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* full oops.
|
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*/
|
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static void zap_locks(void)
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{
|
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static unsigned long oops_timestamp;
|
|
|
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if (time_after_eq(jiffies, oops_timestamp) &&
|
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!time_after(jiffies, oops_timestamp + 30 * HZ))
|
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return;
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|
|
|
oops_timestamp = jiffies;
|
|
|
|
/* If a crash is occurring, make sure we can't deadlock */
|
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spin_lock_init(&logbuf_lock);
|
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/* And make sure that we print immediately */
|
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init_MUTEX(&console_sem);
|
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}
|
|
|
|
#if defined(CONFIG_PRINTK_TIME)
|
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static int printk_time = 1;
|
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#else
|
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static int printk_time = 0;
|
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#endif
|
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module_param(printk_time, int, S_IRUGO | S_IWUSR);
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|
|
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static int __init printk_time_setup(char *str)
|
|
{
|
|
if (*str)
|
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return 0;
|
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printk_time = 1;
|
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return 1;
|
|
}
|
|
|
|
__setup("time", printk_time_setup);
|
|
|
|
__attribute__((weak)) unsigned long long printk_clock(void)
|
|
{
|
|
return sched_clock();
|
|
}
|
|
|
|
/* 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.
|
|
*
|
|
* 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;
|
|
|
|
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;
|
|
|
|
preempt_disable();
|
|
if (unlikely(oops_in_progress) && printk_cpu == smp_processor_id())
|
|
/* If a crash is occurring during printk() on this CPU,
|
|
* make sure we can't deadlock */
|
|
zap_locks();
|
|
|
|
/* This stops the holder of console_sem just where we want him */
|
|
local_irq_save(flags);
|
|
lockdep_off();
|
|
spin_lock(&logbuf_lock);
|
|
printk_cpu = smp_processor_id();
|
|
|
|
/* 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 = printk_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;
|
|
} 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();
|
|
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();
|
|
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 0;
|
|
}
|
|
|
|
int do_syslog(int type, char __user *buf, int len)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
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 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.
|
|
* @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 __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;
|
|
}
|
|
|
|
#ifndef CONFIG_DISABLE_CONSOLE_SUSPEND
|
|
/**
|
|
* suspend_console - suspend the console subsystem
|
|
*
|
|
* This disables printk() while we go into suspend states
|
|
*/
|
|
void suspend_console(void)
|
|
{
|
|
printk("Suspending console(s)\n");
|
|
acquire_console_sem();
|
|
console_suspended = 1;
|
|
}
|
|
|
|
void resume_console(void)
|
|
{
|
|
console_suspended = 0;
|
|
release_console_sem();
|
|
}
|
|
#endif /* CONFIG_DISABLE_CONSOLE_SUSPEND */
|
|
|
|
/**
|
|
* 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;
|
|
}
|
|
EXPORT_UNUSED_SYMBOL(is_console_locked); /* June 2006 */
|
|
|
|
/**
|
|
* 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 && !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();
|
|
}
|
|
|
|
/*
|
|
* 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 == selected_console) {
|
|
console->flags |= CON_CONSDEV;
|
|
preferred_console = selected_console;
|
|
}
|
|
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;
|
|
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 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 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)
|
|
preferred_console = selected_console;
|
|
else if (console->flags & CON_CONSDEV)
|
|
console_drivers->flags |= CON_CONSDEV;
|
|
|
|
release_console_sem();
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(unregister_console);
|
|
|
|
/**
|
|
* 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);
|