kgdb: Turn off tracing while in the debugger

The kernel debugger should turn off kernel tracing any time the
debugger is active and restore it on resume.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Reviewed-by: NSteven Rostedt <rostedt@goodmis.org>

kernel/kgdb.c

@@ -1365,6 +1365,7 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 	int sstep_tries = 100;
 	int error = 0;
 	int i, cpu;
+	int trace_on = 0;
 acquirelock:
 	/*
 	 * Interrupts will be restored by the 'trap return' code, except when
@@ -1399,6 +1400,8 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 			 */
 			if (arch_kgdb_ops.correct_hw_break)
 				arch_kgdb_ops.correct_hw_break();
+			if (trace_on)
+				tracing_on();
 			atomic_dec(&cpu_in_kgdb[cpu]);
 			touch_softlockup_watchdog_sync();
 			clocksource_touch_watchdog();
@@ -1474,6 +1477,9 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 	kgdb_single_step = 0;
 	kgdb_contthread = current;
 	exception_level = 0;
+	trace_on = tracing_is_on();
+	if (trace_on)
+		tracing_off();
 
 	/* Talk to debugger with gdbserial protocol */
 	error = gdb_serial_stub(ks);
@@ -1505,6 +1511,8 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 		else
 			kgdb_sstep_pid = 0;
 	}
+	if (trace_on)
+		tracing_on();
 	/* Free kgdb_active */
 	atomic_set(&kgdb_active, -1);
 	touch_softlockup_watchdog_sync();