lockdep: Fix backtraces

Truncate stupid -1 entries in backtraces.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1248096665.15751.8816.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 11 insertions, 1 deletions

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 1cedb00e3e7a..2f0970297e30 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -367,11 +367,21 @@ static int save_trace(struct stack_trace *trace)
 
         save_stack_trace(trace);
 
+        /*
+         * Some daft arches put -1 at the end to indicate its a full trace.
+         *
+         * <rant> this is buggy anyway, since it takes a whole extra entry so a
+         * complete trace that maxes out the entries provided will be reported
+         * as incomplete, friggin useless </rant>
+         */
+        if (trace->entries[trace->nr_entries-1] == ULONG_MAX)
+                trace->nr_entries--;
+
         trace->max_entries = trace->nr_entries;
 
         nr_stack_trace_entries += trace->nr_entries;
 
-        if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
+        if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
                 if (!debug_locks_off_graph_unlock())
                         return 0;