Merge with /home/tmlind/src/kernel/linux-2.6

[pandora-kernel.git] / kernel / printk.c

diff --git a/kernel/printk.c b/kernel/printk.c
index 477f419..1b053c5 100644 (file)
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -492,6 +492,11 @@ static int __init printk_time_setup(char *str)
 
 __setup("time", printk_time_setup);
 
+__attribute__((weak)) unsigned long long printk_clock(void)
+{
+       return sched_clock();
+}
+
 /*
  * This is printk.  It can be called from any context.  We want it to work.
  * 
@@ -518,6 +523,9 @@ asmlinkage int printk(const char *fmt, ...)
        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;
@@ -526,11 +534,15 @@ asmlinkage int vprintk(const char *fmt, va_list args)
        static char printk_buf[1024];
        static int log_level_unknown = 1;
 
-       if (unlikely(oops_in_progress))
+       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 */
        spin_lock_irqsave(&logbuf_lock, flags);
+       printk_cpu = smp_processor_id();
 
        /* Emit the output into the temporary buffer */
        printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args);
@@ -566,7 +578,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                                        loglev_char = default_message_loglevel
                                                + '0';
                                }
-                               t = sched_clock();
+                               t = printk_clock();
                                nanosec_rem = do_div(t, 1000000000);
                                tlen = sprintf(tbuf,
                                                "<%c>[%5lu.%06lu] ",
@@ -603,6 +615,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                 * CPU until it is officially up.  We shouldn't be calling into
                 * random console drivers on a CPU which doesn't exist yet..
                 */
+               printk_cpu = UINT_MAX;
                spin_unlock_irqrestore(&logbuf_lock, flags);
                goto out;
        }
@@ -612,6 +625,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                 * We own the drivers.  We can drop the spinlock and let
                 * release_console_sem() print the text
                 */
+               printk_cpu = UINT_MAX;
                spin_unlock_irqrestore(&logbuf_lock, flags);
                console_may_schedule = 0;
                release_console_sem();
@@ -621,9 +635,11 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                 * 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_irqrestore(&logbuf_lock, flags);
        }
 out:
+       preempt_enable();
        return printed_len;
 }
 EXPORT_SYMBOL(printk);