Merge rsync://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

[safe/jmp/linux-2.6] / kernel / printk.c

diff --git a/kernel/printk.c b/kernel/printk.c
index 416b8f3..9772b9e 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>
@@ -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
@@ -566,27 +581,29 @@ 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 ...
                 */
+               console_locked = 1;
                printk_cpu = UINT_MAX;
                spin_unlock_irqrestore(&logbuf_lock, flags);
-               goto out;
-       }
-       if (!down_trylock(&console_sem)) {
-               console_locked = 1;
+
                /*
-                * 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);
+               }
        } else {
                /*
                 * Someone else owns the drivers.  We drop the spinlock, which
@@ -596,7 +613,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                printk_cpu = UINT_MAX;
                spin_unlock_irqrestore(&logbuf_lock, flags);
        }
-out:
+
        preempt_enable();
        return printed_len;
 }