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authorChunyu Hu <chuhu@redhat.com>2016-03-08 21:37:01 +0800
committerSteven Rostedt <rostedt@goodmis.org>2016-03-08 11:19:08 -0500
commitd39cdd2036a63eef17a14efbd969405ca5612886 (patch)
tree547098658fa6d9e6dba8ffe73ccd756ba5638668 /kernel
parentf6cede5b49e822ebc41a099fe41ab4989f64e2cb (diff)
downloadop-kernel-dev-d39cdd2036a63eef17a14efbd969405ca5612886.zip
op-kernel-dev-d39cdd2036a63eef17a14efbd969405ca5612886.tar.gz
tracing: Make tracer_flags use the right set_flag callback
When I was updating the ftrace_stress test of ltp. I encountered a strange phenomemon, excute following steps: echo nop > /sys/kernel/debug/tracing/current_tracer echo 0 > /sys/kernel/debug/tracing/options/funcgraph-cpu bash: echo: write error: Invalid argument check dmesg: [ 1024.903855] nop_test_refuse flag set to 0: we refuse.Now cat trace_options to see the result The reason is that the trace option test will randomly setup trace option under tracing/options no matter what the current_tracer is. but the set_tracer_option is always using the set_flag callback from the current_tracer. This patch adds a pointer to tracer_flags and make it point to the tracer it belongs to. When the option is setup, the set_flag of the right tracer will be used no matter what the the current_tracer is. And the old dummy_tracer_flags is used for all the tracers which doesn't have a tracer_flags, having issue to use it to save the pointer of a tracer. So remove it and use dynamic dummy tracer_flags for tracers needing a dummy tracer_flags, as a result, there are no tracers sharing tracer_flags, so remove the check code. And save the current tracer to trace_option_dentry seems not good as it may waste mem space when mount the debug/trace fs more than one time. Link: http://lkml.kernel.org/r/1457444222-8654-1-git-send-email-chuhu@redhat.com Signed-off-by: Chunyu Hu <chuhu@redhat.com> [ Fixed up function tracer options to work with the change ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace.c28
-rw-r--r--kernel/trace/trace.h1
-rw-r--r--kernel/trace/trace_functions.c6
3 files changed, 21 insertions, 14 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d929340..b401a18 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -74,11 +74,6 @@ static struct tracer_opt dummy_tracer_opt[] = {
{ }
};
-static struct tracer_flags dummy_tracer_flags = {
- .val = 0,
- .opts = dummy_tracer_opt
-};
-
static int
dummy_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
{
@@ -1258,12 +1253,20 @@ int __init register_tracer(struct tracer *type)
if (!type->set_flag)
type->set_flag = &dummy_set_flag;
- if (!type->flags)
- type->flags = &dummy_tracer_flags;
- else
+ if (!type->flags) {
+ /*allocate a dummy tracer_flags*/
+ type->flags = kmalloc(sizeof(*type->flags), GFP_KERNEL);
+ if (!type->flags)
+ return -ENOMEM;
+ type->flags->val = 0;
+ type->flags->opts = dummy_tracer_opt;
+ } else
if (!type->flags->opts)
type->flags->opts = dummy_tracer_opt;
+ /* store the tracer for __set_tracer_option */
+ type->flags->trace = type;
+
ret = run_tracer_selftest(type);
if (ret < 0)
goto out;
@@ -3505,7 +3508,7 @@ static int __set_tracer_option(struct trace_array *tr,
struct tracer_flags *tracer_flags,
struct tracer_opt *opts, int neg)
{
- struct tracer *trace = tr->current_trace;
+ struct tracer *trace = tracer_flags->trace;
int ret;
ret = trace->set_flag(tr, tracer_flags->val, opts->bit, !neg);
@@ -6391,11 +6394,8 @@ create_trace_option_files(struct trace_array *tr, struct tracer *tracer)
return;
for (i = 0; i < tr->nr_topts; i++) {
- /*
- * Check if these flags have already been added.
- * Some tracers share flags.
- */
- if (tr->topts[i].tracer->flags == tracer->flags)
+ /* Make sure there's no duplicate flags. */
+ if (WARN_ON_ONCE(tr->topts[i].tracer->flags == tracer->flags))
return;
}
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 8414fa4..b4cae47 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -345,6 +345,7 @@ struct tracer_opt {
struct tracer_flags {
u32 val;
struct tracer_opt *opts;
+ struct tracer *trace;
};
/* Makes more easy to define a tracer opt */
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index fcd41a1..5a095c2 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -219,6 +219,8 @@ static void tracing_stop_function_trace(struct trace_array *tr)
unregister_ftrace_function(tr->ops);
}
+static struct tracer function_trace;
+
static int
func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
{
@@ -228,6 +230,10 @@ func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
break;
+ /* We can change this flag when not running. */
+ if (tr->current_trace != &function_trace)
+ break;
+
unregister_ftrace_function(tr->ops);
if (set) {
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