Merge git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched

* git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched: (96 commits)
  sched: keep total / count stats in addition to the max for
  sched, futex: detach sched.h and futex.h
  sched: fix: don't take a mutex from interrupt context
  sched: print backtrace of running tasks too
  printk: use ktime_get()
  softlockup: fix signedness
  sched: latencytop support
  sched: fix goto retry in pick_next_task_rt()
  timers: don't #error on higher HZ values
  sched: monitor clock underflows in /proc/sched_debug
  sched: fix rq->clock warps on frequency changes
  sched: fix, always create kernel threads with normal priority
  debug: clean up kernel/profile.c
  sched: remove the !PREEMPT_BKL code
  sched: make PREEMPT_BKL the default
  debug: track and print last unloaded module in the oops trace
  debug: show being-loaded/being-unloaded indicator for modules
  sched: rt-watchdog: fix .rlim_max = RLIM_INFINITY
  sched: rt-group: reduce rescheduling
  hrtimer: unlock hrtimer_wakeup
  ...

1 files changed, 41 insertions, 16 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index 89011bf8c106..423a8c765a57 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -573,11 +573,6 @@ static int __init printk_time_setup(char *str)
 
 __setup("time", printk_time_setup);
 
-__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)
 {
@@ -628,30 +623,57 @@ asmlinkage int printk(const char *fmt, ...)
 /* cpu currently holding logbuf_lock */
 static volatile unsigned int printk_cpu = UINT_MAX;
 
+const char printk_recursion_bug_msg [] =
+			KERN_CRIT "BUG: recent printk recursion!\n";
+static int printk_recursion_bug;
+
 asmlinkage int vprintk(const char *fmt, va_list args)
 {
+	static int log_level_unknown = 1;
+	static char printk_buf[1024];
+
 	unsigned long flags;
-	int printed_len;
+	int printed_len = 0;
+	int this_cpu;
 	char *p;
-	static char printk_buf[1024];
-	static int log_level_unknown = 1;
 
 	boot_delay_msec();
 
 	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 */
 	raw_local_irq_save(flags);
+	this_cpu = smp_processor_id();
+
+	/*
+	 * Ouch, printk recursed into itself!
+	 */
+	if (unlikely(printk_cpu == this_cpu)) {
+		/*
+		 * If a crash is occurring during printk() on this CPU,
+		 * then try to get the crash message out but make sure
+		 * we can't deadlock. Otherwise just return to avoid the
+		 * recursion and return - but flag the recursion so that
+		 * it can be printed at the next appropriate moment:
+		 */
+		if (!oops_in_progress) {
+			printk_recursion_bug = 1;
+			goto out_restore_irqs;
+		}
+		zap_locks();
+	}
+
 	lockdep_off();
 	spin_lock(&logbuf_lock);
-	printk_cpu = smp_processor_id();
+	printk_cpu = this_cpu;
 
+	if (printk_recursion_bug) {
+		printk_recursion_bug = 0;
+		strcpy(printk_buf, printk_recursion_bug_msg);
+		printed_len = sizeof(printk_recursion_bug_msg);
+	}
 	/* Emit the output into the temporary buffer */
-	printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args);
+	printed_len += vscnprintf(printk_buf + printed_len,
+				  sizeof(printk_buf), fmt, args);
 
 	/*
 	 * Copy the output into log_buf.  If the caller didn't provide
@@ -680,7 +702,9 @@ asmlinkage int vprintk(const char *fmt, va_list args)
 					loglev_char = default_message_loglevel
 						+ '0';
 				}
-				t = printk_clock();
+				t = 0;
+				if (system_state != SYSTEM_BOOTING)
+					t = ktime_to_ns(ktime_get());
 				nanosec_rem = do_div(t, 1000000000);
 				tlen = sprintf(tbuf,
 						"<%c>[%5lu.%06lu] ",
@@ -744,6 +768,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
 		printk_cpu = UINT_MAX;
 		spin_unlock(&logbuf_lock);
 		lockdep_on();
+out_restore_irqs:
 		raw_local_irq_restore(flags);
 	}