TRACE(): facilitate debugging

- don't deadlock on a runqueue lock in case of a bug inside
  the scheduler
- write printk() messages to TRACE()
- tell user of TRACE() buffer

1 files changed, 9 insertions, 1 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index 89011bf8c1..9eb2dc5e27 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -54,6 +54,12 @@ int console_printk[4] = {
         DEFAULT_CONSOLE_LOGLEVEL,       /* default_console_loglevel */
 };
 
+/* divert printk() messages when we have a LITMUS^RT
+ * debug listener
+ */
+#include <litmus/litmus.h>
+int trace_override = 0;
+
 /*
  * Low level drivers may need that to know if they can schedule in
  * their unblank() callback or not. So let's export it.
@@ -652,6 +658,8 @@ asmlinkage int vprintk(const char *fmt, va_list args)
 
         /* Emit the output into the temporary buffer */
         printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args);
+        if (trace_override)
+                TRACE("%s", printk_buf);
 
         /*
          * Copy the output into log_buf.  If the caller didn't provide
@@ -932,7 +940,7 @@ int is_console_locked(void)
 
 void wake_up_klogd(void)
 {
-        if (!oops_in_progress && waitqueue_active(&log_wait))
+        if (!trace_override && !oops_in_progress && waitqueue_active(&log_wait))
                 wake_up_interruptible(&log_wait);
 }