[PATCH 2.6.21 review I] [24/25] x86_64: do not always end the stack trace with ULONG_MAX

[Andi Kleen <ak@suse.de>]

From: Catalin Marinas <catalin.marinas@arm.com>

It makes more sense to end the stack trace with ULONG_MAX only if
nr_entries < max_entries.  Otherwise, we lose one entry in the long stack
traces and cannot know whether the trace was complete or not.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 arch/x86_64/kernel/stacktrace.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: linux/arch/x86_64/kernel/stacktrace.c
===================================================================
--- linux.orig/arch/x86_64/kernel/stacktrace.c
+++ linux/arch/x86_64/kernel/stacktrace.c
@@ -32,7 +32,7 @@ static void save_stack_address(void *dat
 		trace->skip--;
 		return;
 	}
-	if (trace->nr_entries < trace->max_entries - 1)
+	if (trace->nr_entries < trace->max_entries)
 		trace->entries[trace->nr_entries++] = addr;
 }
 
@@ -49,7 +49,8 @@ static struct stacktrace_ops save_stack_
 void save_stack_trace(struct stack_trace *trace, struct task_struct *task)
 {
 	dump_trace(task, NULL, NULL, &save_stack_ops, trace);
-	trace->entries[trace->nr_entries++] = ULONG_MAX;
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
 EXPORT_SYMBOL(save_stack_trace);
 
-
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