1 files changed, 65 insertions, 25 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 1ce6208fd72..c95b7292be7 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -155,13 +155,6 @@ ns2usecs(cycle_t nsec)
 	return nsec;
 }
 
-cycle_t ftrace_now(int cpu)
-{
-	u64 ts = ring_buffer_time_stamp(cpu);
-	ring_buffer_normalize_time_stamp(cpu, &ts);
-	return ts;
-}
-
 /*
  * The global_trace is the descriptor that holds the tracing
  * buffers for the live tracing. For each CPU, it contains
@@ -178,6 +171,20 @@ static struct trace_array	global_trace;
 
 static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
 
+cycle_t ftrace_now(int cpu)
+{
+	u64 ts;
+
+	/* Early boot up does not have a buffer yet */
+	if (!global_trace.buffer)
+		return trace_clock_local();
+
+	ts = ring_buffer_time_stamp(global_trace.buffer, cpu);
+	ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts);
+
+	return ts;
+}
+
 /*
  * The max_tr is used to snapshot the global_trace when a maximum
  * latency is reached. Some tracers will use this to store a maximum
@@ -308,6 +315,7 @@ static const char *trace_options[] = {
 	"printk-msg-only",
 	"context-info",
 	"latency-format",
+	"global-clock",
 	NULL
 };
 
@@ -633,6 +641,7 @@ void tracing_reset_online_cpus(struct trace_array *tr)
 }
 
 #define SAVED_CMDLINES 128
+#define NO_CMDLINE_MAP UINT_MAX
 static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
 static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
 static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
@@ -644,8 +653,8 @@ static atomic_t trace_record_cmdline_disabled __read_mostly;
 
 static void trace_init_cmdlines(void)
 {
-	memset(&map_pid_to_cmdline, -1, sizeof(map_pid_to_cmdline));
-	memset(&map_cmdline_to_pid, -1, sizeof(map_cmdline_to_pid));
+	memset(&map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(map_pid_to_cmdline));
+	memset(&map_cmdline_to_pid, NO_CMDLINE_MAP, sizeof(map_cmdline_to_pid));
 	cmdline_idx = 0;
 }
 
@@ -737,8 +746,7 @@ void trace_stop_cmdline_recording(void);
 
 static void trace_save_cmdline(struct task_struct *tsk)
 {
-	unsigned map;
-	unsigned idx;
+	unsigned pid, idx;
 
 	if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
 		return;
@@ -753,13 +761,20 @@ static void trace_save_cmdline(struct task_struct *tsk)
 		return;
 
 	idx = map_pid_to_cmdline[tsk->pid];
-	if (idx >= SAVED_CMDLINES) {
+	if (idx == NO_CMDLINE_MAP) {
 		idx = (cmdline_idx + 1) % SAVED_CMDLINES;
 
-		map = map_cmdline_to_pid[idx];
-		if (map <= PID_MAX_DEFAULT)
-			map_pid_to_cmdline[map] = (unsigned)-1;
+		/*
+		 * Check whether the cmdline buffer at idx has a pid
+		 * mapped. We are going to overwrite that entry so we
+		 * need to clear the map_pid_to_cmdline. Otherwise we
+		 * would read the new comm for the old pid.
+		 */
+		pid = map_cmdline_to_pid[idx];
+		if (pid != NO_CMDLINE_MAP)
+			map_pid_to_cmdline[pid] = NO_CMDLINE_MAP;
 
+		map_cmdline_to_pid[idx] = tsk->pid;
 		map_pid_to_cmdline[tsk->pid] = idx;
 
 		cmdline_idx = idx;
@@ -786,18 +801,18 @@ void trace_find_cmdline(int pid, char comm[])
 
 	__raw_spin_lock(&trace_cmdline_lock);
 	map = map_pid_to_cmdline[pid];
-	if (map >= SAVED_CMDLINES)
-		goto out;
-
-	strcpy(comm, saved_cmdlines[map]);
+	if (map != NO_CMDLINE_MAP)
+		strcpy(comm, saved_cmdlines[map]);
+	else
+		strcpy(comm, "<...>");
 
- out:
 	__raw_spin_unlock(&trace_cmdline_lock);
 }
 
 void tracing_record_cmdline(struct task_struct *tsk)
 {
-	if (atomic_read(&trace_record_cmdline_disabled) || !tracing_is_on())
+	if (atomic_read(&trace_record_cmdline_disabled) || !tracer_enabled ||
+	    !tracing_is_on())
 		return;
 
 	trace_save_cmdline(tsk);
@@ -2244,6 +2259,34 @@ static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
 	return 0;
 }
 
+static void set_tracer_flags(unsigned int mask, int enabled)
+{
+	/* do nothing if flag is already set */
+	if (!!(trace_flags & mask) == !!enabled)
+		return;
+
+	if (enabled)
+		trace_flags |= mask;
+	else
+		trace_flags &= ~mask;
+
+	if (mask == TRACE_ITER_GLOBAL_CLK) {
+		u64 (*func)(void);
+
+		if (enabled)
+			func = trace_clock_global;
+		else
+			func = trace_clock_local;
+
+		mutex_lock(&trace_types_lock);
+		ring_buffer_set_clock(global_trace.buffer, func);
+
+		if (max_tr.buffer)
+			ring_buffer_set_clock(max_tr.buffer, func);
+		mutex_unlock(&trace_types_lock);
+	}
+}
+
 static ssize_t
 tracing_trace_options_write(struct file *filp, const char __user *ubuf,
 			size_t cnt, loff_t *ppos)
@@ -2271,10 +2314,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
 		int len = strlen(trace_options[i]);
 
 		if (strncmp(cmp, trace_options[i], len) == 0) {
-			if (neg)
-				trace_flags &= ~(1 << i);
-			else
-				trace_flags |= (1 << i);
+			set_tracer_flags(1 << i, !neg);
 			break;
 		}
 	}