debug lockups: Improve lockup detection, fix generic arch fallback
As Andrew noted, my previous patch ("debug lockups: Improve lockup
detection") broke/removed SysRq-L support from architecture that do
not provide a __trigger_all_cpu_backtrace implementation.
Restore a fallback path and clean up the SysRq-L machinery a bit:
- Rename the arch method to arch_trigger_all_cpu_backtrace()
- Simplify the define
- Document the method a bit - in the hope of more architectures
adding support for it.
[ The patch touches Sparc code for the rename. ]
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
LKML-Reference: <20090802140809.7ec4bb6b.akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 29af2d5..b752e80 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -28,8 +28,23 @@
static inline void acpi_nmi_enable(void) { }
#endif
-#ifndef trigger_all_cpu_backtrace
-#define trigger_all_cpu_backtrace() do { } while (0)
+/*
+ * Create trigger_all_cpu_backtrace() out of the arch-provided
+ * base function. Return whether such support was available,
+ * to allow calling code to fall back to some other mechanism:
+ */
+#ifdef arch_trigger_all_cpu_backtrace
+static inline bool trigger_all_cpu_backtrace(void)
+{
+ arch_trigger_all_cpu_backtrace();
+
+ return true;
+}
+#else
+static inline bool trigger_all_cpu_backtrace(void)
+{
+ return false;
+}
#endif
#endif