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-rw-r--r--Documentation/trace/ftrace.txt38
-rw-r--r--kernel/trace/trace.c4
2 files changed, 23 insertions, 19 deletions
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 65eddb7cfa02..67f1cc473257 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -80,11 +80,11 @@ of ftrace. Here is a list of some of the key files:
tracers listed here can be configured by
echoing their name into current_tracer.
- tracing_enabled:
+ tracing_on:
- This sets or displays whether the current_tracer
- is activated and tracing or not. Echo 0 into this
- file to disable the tracer or 1 to enable it.
+ This sets or displays whether writing to the trace
+ ring buffer is enabled. Echo 0 into this file to disable
+ the tracer or 1 to enable it.
trace:
@@ -497,10 +497,10 @@ an example:
# echo irqsoff > current_tracer
# echo latency-format > trace_options
# echo 0 > tracing_max_latency
- # echo 1 > tracing_enabled
+ # echo 1 > tracing_on
# ls -ltr
[...]
- # echo 0 > tracing_enabled
+ # echo 0 > tracing_on
# cat trace
# tracer: irqsoff
#
@@ -605,10 +605,10 @@ is much like the irqsoff tracer.
# echo preemptoff > current_tracer
# echo latency-format > trace_options
# echo 0 > tracing_max_latency
- # echo 1 > tracing_enabled
+ # echo 1 > tracing_on
# ls -ltr
[...]
- # echo 0 > tracing_enabled
+ # echo 0 > tracing_on
# cat trace
# tracer: preemptoff
#
@@ -753,10 +753,10 @@ tracers.
# echo preemptirqsoff > current_tracer
# echo latency-format > trace_options
# echo 0 > tracing_max_latency
- # echo 1 > tracing_enabled
+ # echo 1 > tracing_on
# ls -ltr
[...]
- # echo 0 > tracing_enabled
+ # echo 0 > tracing_on
# cat trace
# tracer: preemptirqsoff
#
@@ -916,9 +916,9 @@ Instead of performing an 'ls', we will run 'sleep 1' under
# echo wakeup > current_tracer
# echo latency-format > trace_options
# echo 0 > tracing_max_latency
- # echo 1 > tracing_enabled
+ # echo 1 > tracing_on
# chrt -f 5 sleep 1
- # echo 0 > tracing_enabled
+ # echo 0 > tracing_on
# cat trace
# tracer: wakeup
#
@@ -1030,9 +1030,9 @@ ftrace_enabled is set; otherwise this tracer is a nop.
# sysctl kernel.ftrace_enabled=1
# echo function > current_tracer
- # echo 1 > tracing_enabled
+ # echo 1 > tracing_on
# usleep 1
- # echo 0 > tracing_enabled
+ # echo 0 > tracing_on
# cat trace
# tracer: function
#
@@ -1070,7 +1070,7 @@ int trace_fd;
[...]
int main(int argc, char *argv[]) {
[...]
- trace_fd = open(tracing_file("tracing_enabled"), O_WRONLY);
+ trace_fd = open(tracing_file("tracing_on"), O_WRONLY);
[...]
if (condition_hit()) {
write(trace_fd, "0", 1);
@@ -1521,9 +1521,9 @@ If I am only interested in sys_nanosleep and hrtimer_interrupt:
# echo sys_nanosleep hrtimer_interrupt \
> set_ftrace_filter
# echo function > current_tracer
- # echo 1 > tracing_enabled
+ # echo 1 > tracing_on
# usleep 1
- # echo 0 > tracing_enabled
+ # echo 0 > tracing_on
# cat trace
# tracer: ftrace
#
@@ -1769,9 +1769,9 @@ different. The trace is live.
# echo function > current_tracer
# cat trace_pipe > /tmp/trace.out &
[1] 4153
- # echo 1 > tracing_enabled
+ # echo 1 > tracing_on
# usleep 1
- # echo 0 > tracing_enabled
+ # echo 0 > tracing_on
# cat trace
# tracer: function
#
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dc53ecb80589..8dc8da6733f9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2710,6 +2710,10 @@ tracing_ctrl_write(struct file *filp, const char __user *ubuf,
mutex_lock(&trace_types_lock);
if (tracer_enabled ^ val) {
+
+ /* Only need to warn if this is used to change the state */
+ WARN_ONCE(1, "tracing_enabled is deprecated. Use tracing_on");
+
if (val) {
tracer_enabled = 1;
if (current_trace->start)