* Ted Ts'o, 2/11/93.
* Modified for sysctl support, 1/8/97, Chris Horn.
* Fixed SMP synchronization, 08/08/99, Manfred Spraul
- * manfreds@colorfullife.com
+ * manfred@colorfullife.com
* Rewrote bits to get rid of console_lock
* 01Mar01 Andrew Morton <andrewm@uow.edu.au>
*/
#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/config.h>
#include <linux/delay.h>
#include <linux/smp.h>
#include <linux/security.h>
DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
};
-EXPORT_SYMBOL(console_printk);
+EXPORT_UNUSED_SYMBOL(console_printk); /* June 2006 */
/*
* Low lever drivers may need that to know if they can schedule in
* 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
* path in the console code where we end up in places I want
* locked without the console sempahore held
*/
-static int console_locked;
+static int console_locked, console_suspended;
/*
* logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars
static int log_buf_len = __LOG_BUF_LEN;
static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */
-/*
- * Setup a list of consoles. Called from init/main.c
- */
-static int __init console_setup(char *str)
-{
- char name[sizeof(console_cmdline[0].name)];
- char *s, *options;
- int idx;
-
- /*
- * Decode str into name, index, options.
- */
- if (str[0] >= '0' && str[0] <= '9') {
- strcpy(name, "ttyS");
- strncpy(name + 4, str, sizeof(name) - 5);
- } else
- strncpy(name, str, sizeof(name) - 1);
- name[sizeof(name) - 1] = 0;
- if ((options = strchr(str, ',')) != NULL)
- *(options++) = 0;
-#ifdef __sparc__
- if (!strcmp(str, "ttya"))
- strcpy(name, "ttyS0");
- if (!strcmp(str, "ttyb"))
- strcpy(name, "ttyS1");
-#endif
- for (s = name; *s; s++)
- if ((*s >= '0' && *s <= '9') || *s == ',')
- break;
- idx = simple_strtoul(s, NULL, 10);
- *s = 0;
-
- add_preferred_console(name, idx, options);
- return 1;
-}
-
-__setup("console=", console_setup);
-
static int __init log_buf_len_setup(char *str)
{
unsigned long size = memparse(str, &str);
struct console *con;
for (con = console_drivers; con; con = con->next) {
- if ((con->flags & CON_ENABLED) && con->write)
+ if ((con->flags & CON_ENABLED) && con->write &&
+ (cpu_online(smp_processor_id()) ||
+ (con->flags & CON_ANYTIME)))
con->write(con, &LOG_BUF(start), end - start);
}
}
unsigned long cur_index, start_print;
static int msg_level = -1;
- if (((long)(start - end)) > 0)
- BUG();
+ BUG_ON(((long)(start - end)) > 0);
cur_index = start;
start_print = start;
#else
static int printk_time = 0;
#endif
+module_param(printk_time, int, S_IRUGO | S_IWUSR);
static int __init printk_time_setup(char *str)
{
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
* 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, ...)
zap_locks();
/* This stops the holder of console_sem just where we want him */
- spin_lock_irqsave(&logbuf_lock, flags);
+ local_irq_save(flags);
+ lockdep_off();
+ spin_lock(&logbuf_lock);
printk_cpu = smp_processor_id();
/* Emit the output into the temporary buffer */
p[1] <= '7' && p[2] == '>') {
loglev_char = p[1];
p += 3;
- printed_len += 3;
+ printed_len -= 3;
} else {
loglev_char = default_message_loglevel
+ '0';
for (tp = tbuf; tp < tbuf + tlen; tp++)
emit_log_char(*tp);
- printed_len += tlen - 3;
+ printed_len += tlen;
} else {
if (p[0] != '<' || p[1] < '0' ||
p[1] > '7' || p[2] != '>') {
emit_log_char(default_message_loglevel
+ '0');
emit_log_char('>');
+ printed_len += 3;
}
- printed_len += 3;
}
log_level_unknown = 0;
if (!*p)
log_level_unknown = 1;
}
- if (!cpu_online(smp_processor_id())) {
+ if (!down_trylock(&console_sem)) {
/*
- * Some console drivers may assume that per-cpu resources have
- * been allocated. So don't allow them to be called by this
- * CPU until it is officially up. We shouldn't be calling into
- * random console drivers on a CPU which doesn't exist yet..
+ * We own the drivers. We can drop the spinlock and
+ * let release_console_sem() print the text, maybe ...
*/
- printk_cpu = UINT_MAX;
- spin_unlock_irqrestore(&logbuf_lock, flags);
- goto out;
- }
- if (!down_trylock(&console_sem)) {
console_locked = 1;
+ printk_cpu = UINT_MAX;
+ spin_unlock(&logbuf_lock);
+
/*
- * We own the drivers. We can drop the spinlock and let
- * release_console_sem() print the text
+ * 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.
*/
- printk_cpu = UINT_MAX;
- spin_unlock_irqrestore(&logbuf_lock, flags);
- console_may_schedule = 0;
- release_console_sem();
+ 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
* console drivers with the output which we just produced.
*/
printk_cpu = UINT_MAX;
- spin_unlock_irqrestore(&logbuf_lock, flags);
+ spin_unlock(&logbuf_lock);
+ lockdep_on();
+ local_irq_restore(flags);
}
-out:
+
preempt_enable();
return printed_len;
}
#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
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.
*
*/
void acquire_console_sem(void)
{
- if (in_interrupt())
- BUG();
+ BUG_ON(in_interrupt());
+ if (console_suspended) {
+ down(&secondary_console_sem);
+ return;
+ }
down(&console_sem);
console_locked = 1;
console_may_schedule = 1;
{
return console_locked;
}
-EXPORT_SYMBOL(is_console_locked);
+EXPORT_UNUSED_SYMBOL(is_console_locked); /* June 2006 */
/**
* release_console_sem - unlock the console system
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;
console_may_schedule = 0;
up(&console_sem);
spin_unlock_irqrestore(&logbuf_lock, flags);
- if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait))
- wake_up_interruptible(&log_wait);
+ 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
+/**
+ * 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
if (console_drivers == console) {
console_drivers=console->next;
res = 0;
- } else {
+ } else if (console_drivers) {
for (a=console_drivers->next, b=console_drivers ;
a; b=a, a=b->next) {
if (a == 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
projects / linux-2.6 / blobdiff