1 files changed, 35 insertions, 16 deletions

diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index eb1534ff1f5f..bd0891f4c2c7 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -107,6 +107,7 @@ static inline void preempt_conditional_cli(struct pt_regs *regs)
 }
 
 static int kstack_depth_to_print = 10;
+static int call_trace = 1;
 
 #ifdef CONFIG_KALLSYMS
 #include <linux/kallsyms.h> 
@@ -190,11 +191,12 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
         return NULL;
 }
 
-static void show_trace_unwind(struct unwind_frame_info *info, void *context)
+static int show_trace_unwind(struct unwind_frame_info *info, void *context)
 {
-        int i = 11;
+        int i = 11, n = 0;
 
         while (unwind(info) == 0 && UNW_PC(info)) {
+                ++n;
                 if (i > 50) {
                         printk("\n       ");
                         i = 7;
@@ -205,6 +207,7 @@ static void show_trace_unwind(struct unwind_frame_info *info, void *context)
                         break;
         }
         printk("\n");
+        return n;
 }
 
 /*
@@ -218,27 +221,32 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
 {
         const unsigned cpu = safe_smp_processor_id();
         unsigned long *irqstack_end = (unsigned long *)cpu_pda(cpu)->irqstackptr;
-        int i;
+        int i = 11;
         unsigned used = 0;
-        struct unwind_frame_info info;
 
         printk("\nCall Trace:");
 
         if (!tsk)
                 tsk = current;
 
-        if (regs) {
-                if (unwind_init_frame_info(&info, tsk, regs) == 0) {
-                        show_trace_unwind(&info, NULL);
-                        return;
+        if (call_trace >= 0) {
+                int unw_ret = 0;
+                struct unwind_frame_info info;
+
+                if (regs) {
+                        if (unwind_init_frame_info(&info, tsk, regs) == 0)
+                                unw_ret = show_trace_unwind(&info, NULL);
+                } else if (tsk == current)
+                        unw_ret = unwind_init_running(&info, show_trace_unwind, NULL);
+                else {
+                        if (unwind_init_blocked(&info, tsk) == 0)
+                                unw_ret = show_trace_unwind(&info, NULL);
                 }
-        } else if (tsk == current) {
-                if (unwind_init_running(&info, show_trace_unwind, NULL) == 0)
-                        return;
-        } else {
-                if (unwind_init_blocked(&info, tsk) == 0) {
-                        show_trace_unwind(&info, NULL);
-                        return;
+                if (unw_ret > 0) {
+                        if (call_trace > 0)
+                                return;
+                        printk("Legacy call trace:");
+                        i = 18;
                 }
         }
 
@@ -264,7 +272,7 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
                 } \
         } while (0)
 
-        for(i = 11; ; ) {
+        for(; ; ) {
                 const char *id;
                 unsigned long *estack_end;
                 estack_end = in_exception_stack(cpu, (unsigned long)stack,
@@ -1052,3 +1060,14 @@ static int __init kstack_setup(char *s)
 }
 __setup("kstack=", kstack_setup);
 
+static int __init call_trace_setup(char *s)
+{
+        if (strcmp(s, "old") == 0)
+                call_trace = -1;
+        else if (strcmp(s, "both") == 0)
+                call_trace = 0;
+        else if (strcmp(s, "new") == 0)
+                call_trace = 1;
+        return 1;
+}
+__setup("call_trace=", call_trace_setup);