[PATCH 2/3] powerpc/xmon: Disable and enable tracing command

[Breno Leitao]

If tracing is enabled and you get into xmon, the tracing buffer
continues to be updated, causing possible loss of data due to buffer
overflow and unnecessary tracing information coming from xmon functions.

This patch adds a new option that allows the tracing to be disabled and
re-enabled from inside xmon.

Signed-off-by: Breno Leitao <leitao at debian.org>
---
 arch/powerpc/xmon/xmon.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 0cbd910193fa..19276d2f2f25 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -89,6 +89,7 @@ static unsigned long nidump = 16;
 static unsigned long ncsum = 4096;
 static int termch;
 static char tmpstr[128];
+static char tracing_enabled = 1;
 
 static long bus_error_jmp[JMP_BUF_LEN];
 static int catch_memory_errors;
@@ -268,6 +269,7 @@ Commands:\n\
   Sr #	read SPR #\n\
   Sw #v write v to SPR #\n\
   t	print backtrace\n\
+  v	trace enable/disable\n\
   x	exit monitor and recover\n\
   X	exit monitor and don't recover\n"
 #if defined(CONFIG_PPC64) && !defined(CONFIG_PPC_BOOK3E)
@@ -983,6 +985,17 @@ cmds(struct pt_regs *excp)
 		case 'x':
 		case 'X':
 			return cmd;
+		case 'v':
+			if (tracing_is_on()) {
+				printk("Disabling tracing\n");
+				tracing_enabled = 0;
+				tracing_off();
+			} else {
+				printk("Enabling tracing\n");
+				tracing_enabled = 1;
+				tracing_on();
+			}
+			break;
 		case EOF:
 			printf(" <no input ...>\n");
 			mdelay(2000);
@@ -2353,7 +2366,8 @@ static void dump_tracing(void)
 	else
 		ftrace_dump(DUMP_ALL);
 
-	tracing_on();
+	if (tracing_enabled)
+		tracing_on();
 }
 
 static void dump_all_pacas(void)
-- 
2.13.2