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>
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@ -74,11 +74,6 @@ static struct tracer_opt dummy_tracer_opt[] = {
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{ }
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};
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static struct tracer_flags dummy_tracer_flags = {
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.val = 0,
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.opts = dummy_tracer_opt
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};
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static int
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dummy_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
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{
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@ -1258,12 +1253,20 @@ int __init register_tracer(struct tracer *type)
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if (!type->set_flag)
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type->set_flag = &dummy_set_flag;
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if (!type->flags)
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type->flags = &dummy_tracer_flags;
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else
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if (!type->flags) {
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/*allocate a dummy tracer_flags*/
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type->flags = kmalloc(sizeof(*type->flags), GFP_KERNEL);
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if (!type->flags)
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return -ENOMEM;
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type->flags->val = 0;
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type->flags->opts = dummy_tracer_opt;
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} else
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if (!type->flags->opts)
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type->flags->opts = dummy_tracer_opt;
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/* store the tracer for __set_tracer_option */
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type->flags->trace = type;
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ret = run_tracer_selftest(type);
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if (ret < 0)
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goto out;
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@ -3505,7 +3508,7 @@ static int __set_tracer_option(struct trace_array *tr,
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struct tracer_flags *tracer_flags,
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struct tracer_opt *opts, int neg)
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{
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struct tracer *trace = tr->current_trace;
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struct tracer *trace = tracer_flags->trace;
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int ret;
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ret = trace->set_flag(tr, tracer_flags->val, opts->bit, !neg);
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@ -6391,11 +6394,8 @@ create_trace_option_files(struct trace_array *tr, struct tracer *tracer)
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return;
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for (i = 0; i < tr->nr_topts; i++) {
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/*
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* Check if these flags have already been added.
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* Some tracers share flags.
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*/
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if (tr->topts[i].tracer->flags == tracer->flags)
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/* Make sure there's no duplicate flags. */
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if (WARN_ON_ONCE(tr->topts[i].tracer->flags == tracer->flags))
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return;
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}
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@ -345,6 +345,7 @@ struct tracer_opt {
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struct tracer_flags {
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u32 val;
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struct tracer_opt *opts;
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struct tracer *trace;
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};
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/* Makes more easy to define a tracer opt */
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@ -219,6 +219,8 @@ static void tracing_stop_function_trace(struct trace_array *tr)
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unregister_ftrace_function(tr->ops);
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}
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static struct tracer function_trace;
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static int
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func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
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{
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@ -228,6 +230,10 @@ func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
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if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
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break;
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/* We can change this flag when not running. */
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if (tr->current_trace != &function_trace)
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break;
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unregister_ftrace_function(tr->ops);
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if (set) {
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