1 files changed, 82 insertions, 26 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index c056f3324432..65ca0688f86f 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -24,8 +24,8 @@
 #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>
@@ -52,7 +52,7 @@ int console_printk[4] = {
         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
@@ -67,6 +67,7 @@ EXPORT_SYMBOL(oops_in_progress);
  * 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
@@ -76,7 +77,7 @@ struct console *console_drivers;
  * 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
@@ -326,7 +327,9 @@ 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)
+                if ((con->flags & CON_ENABLED) && con->write &&
+                                (cpu_online(smp_processor_id()) ||
+                                (con->flags & CON_ANYTIME)))
                         con->write(con, &LOG_BUF(start), end - start);
         }
 }
@@ -436,6 +439,7 @@ 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)
 {
@@ -452,6 +456,18 @@ __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
@@ -502,7 +518,9 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                 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 */
@@ -565,27 +583,31 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                         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
@@ -593,9 +615,11 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                  * 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;
 }
@@ -698,6 +722,23 @@ int __init add_preferred_console(char *name, int idx, char *options)
 }
 
 /**
+ * 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
@@ -708,6 +749,10 @@ int __init add_preferred_console(char *name, int idx, char *options)
 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;
@@ -728,7 +773,7 @@ int is_console_locked(void)
 {
         return console_locked;
 }
-EXPORT_SYMBOL(is_console_locked);
+EXPORT_UNUSED_SYMBOL(is_console_locked);  /*  June 2006  */
 
 /**
  * release_console_sem - unlock the console system
@@ -750,6 +795,10 @@ void release_console_sem(void)
         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;
@@ -766,8 +815,15 @@ void release_console_sem(void)
         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);