| /* |
| * 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/smp_lock.h> |
| #include <linux/console.h> |
| #include <linux/init.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 <asm/uaccess.h> |
| |
| #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) |
| |
| /* printk's without a loglevel use this.. */ |
| #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */ |
| |
| /* We show everything that is MORE important than this.. */ |
| #define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */ |
| #define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */ |
| |
| DECLARE_WAIT_QUEUE_HEAD(log_wait); |
| |
| int console_printk[4] = { |
| DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */ |
| DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */ |
| MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */ |
| DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */ |
| }; |
| |
| EXPORT_SYMBOL(console_printk); |
| |
| /* |
| * Low lever drivers may need that to know if they can schedule in |
| * their unblank() callback or not. So let's export it. |
| */ |
| int oops_in_progress; |
| EXPORT_SYMBOL(oops_in_progress); |
| |
| /* |
| * console_sem protects the console_drivers list, and also |
| * provides serialisation for access to the entire console |
| * driver system. |
| */ |
| static DECLARE_MUTEX(console_sem); |
| 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); |
| |
| /* |
| * 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); |
| } |
| } |
| |
| /* |
| * Write out chars from start to end - 1 inclusive |
| */ |
| static void _call_console_drivers(unsigned long start, |
| unsigned long end, int msg_log_level) |
| { |
| if (msg_log_level < console_loglevel && |
| console_drivers && start != end) { |
| if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { |
| /* wrapped write */ |
| __call_console_drivers(start & LOG_BUF_MASK, |
| log_buf_len); |
| __call_console_drivers(0, end & LOG_BUF_MASK); |
| } else { |
| __call_console_drivers(start, end); |
| } |
| } |
| } |
| |
| /* |
| * Call the console drivers, asking them to write out |
| * log_buf[start] to log_buf[end - 1]. |
| * The console_sem must be held. |
| */ |
| static void call_console_drivers(unsigned long start, unsigned long end) |
| { |
| unsigned long cur_index, start_print; |
| static int msg_level = -1; |
| |
| 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(printk_time, int, S_IRUGO | S_IWUSR); |
| |
| static int __init printk_time_setup(char *str) |
| { |
| if (*str) |
| return 0; |
| printk_time = 1; |
| 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; |
| } |
| |
| /** |
| * suspend_console - suspend the console subsystem |
| * |
| * This disables printk() while we go into suspend states |
| */ |
| void suspend_console(void) |
| { |
| acquire_console_sem(); |
| console_suspended = 1; |
| } |
| |
| void resume_console(void) |
| { |
| 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; |
| } |
| EXPORT_SYMBOL(is_console_locked); |
| |
| /** |
| * release_console_sem - unlock the console system |
| * |
| * Releases the semaphore which the caller holds on the console system |
| * and the console driver list. |
| * |
| * While the semaphore was held, console output may have been buffered |
| * by printk(). If this is the case, release_console_sem() emits |
| * the output prior to releasing the semaphore. |
| * |
| * If there is output waiting for klogd, we wake it up. |
| * |
| * release_console_sem() may be called from any context. |
| */ |
| void release_console_sem(void) |
| { |
| unsigned long flags; |
| unsigned long _con_start, _log_end; |
| unsigned long wake_klogd = 0; |
| |
| if (console_suspended) { |
| up(&secondary_console_sem); |
| return; |
| } |
| for ( ; ; ) { |
| spin_lock_irqsave(&logbuf_lock, flags); |
| wake_klogd |= log_start - log_end; |
| if (con_start == log_end) |
| break; /* Nothing to print */ |
| _con_start = con_start; |
| _log_end = log_end; |
| con_start = log_end; /* Flush */ |
| spin_unlock(&logbuf_lock); |
| call_console_drivers(_con_start, _log_end); |
| local_irq_restore(flags); |
| } |
| console_locked = 0; |
| console_may_schedule = 0; |
| up(&console_sem); |
| spin_unlock_irqrestore(&logbuf_lock, flags); |
| if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait)) { |
| /* |
| * If we printk from within the lock dependency code, |
| * from within the scheduler code, then do not lock |
| * up due to self-recursion: |
| */ |
| if (!lockdep_internal()) |
| 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); |