Merge branch 'master' into upstream

[sfrench/cifs-2.6.git] / kernel / printk.c

diff --git a/kernel/printk.c b/kernel/printk.c
index 19a95561929478ffc99ac1552cf3ab645ec16bc1..771f5e861bcd38af1d5d7f91666b2413b1d4008b 100644 (file)
--- 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
@@ -327,7 +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);
        }
 }
@@ -437,6 +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)
 {
@@ -453,6 +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
@@ -503,7 +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 */
@@ -566,27 +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
@@ -594,9 +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 +721,7 @@ int __init add_preferred_console(char *name, int idx, char *options)
        return 0;
 }
 
+#ifndef CONFIG_DISABLE_CONSOLE_SUSPEND
 /**
  * suspend_console - suspend the console subsystem
  *
@@ -705,6 +729,7 @@ int __init add_preferred_console(char *name, int idx, char *options)
  */
 void suspend_console(void)
 {
+       printk("Suspending console(s)\n");
        acquire_console_sem();
        console_suspended = 1;
 }
@@ -714,6 +739,7 @@ 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.
@@ -750,7 +776,7 @@ 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
@@ -776,6 +802,9 @@ void release_console_sem(void)
                up(&secondary_console_sem);
                return;
        }
+
+       console_may_schedule = 0;
+
        for ( ; ; ) {
                spin_lock_irqsave(&logbuf_lock, flags);
                wake_klogd |= log_start - log_end;
@@ -789,11 +818,17 @@ void release_console_sem(void)
                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))
-               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);