From: Namhyung Kim <namhyung@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Frederic Weisbecker <frederic@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Andy Lutomirski <luto@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
kernel-team@lge.com
Subject: Re: [RFC][PATCH 02/14] fgraph: Have set_graph_notrace only affect function_graph tracer
Date: Fri, 23 Nov 2018 09:01:18 +0900 [thread overview]
Message-ID: <20181123000118.GB25952@sejong> (raw)
In-Reply-To: <20181122012802.894046175@goodmis.org>
Hi Steve,
On Wed, Nov 21, 2018 at 08:27:10PM -0500, Steven Rostedt wrote:
> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
>
> In order to make the function graph infrastructure more generic, there can
> not be code specific for the function_graph tracer in the generic code. This
> includes the set_graph_notrace logic, that stops all graph calls when a
> function in the set_graph_notrace is hit.
>
> By using the trace_recursion mask, we can use a bit in the current
> task_struct to implement the notrace code, and move the logic out of
> fgraph.c and into trace_functions_graph.c and keeps it affecting only the
> tracer and not all call graph callbacks.
>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Thanks,
Namhyung
> ---
> kernel/trace/fgraph.c | 21 ---------------------
> kernel/trace/trace.h | 6 ++++++
> kernel/trace/trace_functions_graph.c | 21 +++++++++++++++++++++
> 3 files changed, 27 insertions(+), 21 deletions(-)
>
> diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> index e8fcf1b2b38c..c684968b87e7 100644
> --- a/kernel/trace/fgraph.c
> +++ b/kernel/trace/fgraph.c
> @@ -64,30 +64,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> return -EBUSY;
> }
>
> - /*
> - * The curr_ret_stack is an index to ftrace return stack of
> - * current task. Its value should be in [0, FTRACE_RETFUNC_
> - * DEPTH) when the function graph tracer is used. To support
> - * filtering out specific functions, it makes the index
> - * negative by subtracting huge value (FTRACE_NOTRACE_DEPTH)
> - * so when it sees a negative index the ftrace will ignore
> - * the record. And the index gets recovered when returning
> - * from the filtered function by adding the FTRACE_NOTRACE_
> - * DEPTH and then it'll continue to record functions normally.
> - *
> - * The curr_ret_stack is initialized to -1 and get increased
> - * in this function. So it can be less than -1 only if it was
> - * filtered out via ftrace_graph_notrace_addr() which can be
> - * set from set_graph_notrace file in tracefs by user.
> - */
> - if (current->curr_ret_stack < -1)
> - return -EBUSY;
> -
> calltime = trace_clock_local();
>
> index = ++current->curr_ret_stack;
> - if (ftrace_graph_notrace_addr(func))
> - current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH;
> barrier();
> current->ret_stack[index].ret = ret;
> current->ret_stack[index].func = func;
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 3b8c0e24ab30..f3ad85830961 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -512,6 +512,12 @@ enum {
> * can only be modified by current, we can reuse trace_recursion.
> */
> TRACE_IRQ_BIT,
> +/*
> + * To implement set_graph_notrace, if this bit is set, we ignore
> + * function graph tracing of called functions, until the return
> + * function is called to clear it.
> + */
> + TRACE_GRAPH_NOTRACE_BIT,
> };
>
> #define trace_recursion_set(bit) do { (current)->trace_recursion |= (1<<(bit)); } while (0)
> diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
> index af1759cd6eab..4748dc1bf5e1 100644
> --- a/kernel/trace/trace_functions_graph.c
> +++ b/kernel/trace/trace_functions_graph.c
> @@ -188,6 +188,18 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
> int cpu;
> int pc;
>
> + if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT))
> + return 0;
> +
> + if (ftrace_graph_notrace_addr(trace->func)) {
> + trace_recursion_set(TRACE_GRAPH_NOTRACE_BIT);
> + /*
> + * Need to return 1 to have the return called
> + * that will clear the NOTRACE bit.
> + */
> + return 1;
> + }
> +
> if (!ftrace_trace_task(tr))
> return 0;
>
> @@ -288,6 +300,11 @@ void trace_graph_return(struct ftrace_graph_ret *trace)
> int cpu;
> int pc;
>
> + if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
> + trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
> + return;
> + }
> +
> local_irq_save(flags);
> cpu = raw_smp_processor_id();
> data = per_cpu_ptr(tr->trace_buffer.data, cpu);
> @@ -311,6 +328,10 @@ void set_graph_array(struct trace_array *tr)
>
> static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
> {
> + if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
> + trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
> + return;
> + }
> if (tracing_thresh &&
> (trace->rettime - trace->calltime < tracing_thresh))
> return;
> --
> 2.19.1
>
>
next prev parent reply other threads:[~2018-11-23 0:01 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-22 1:27 [RFC][PATCH 00/14] function_graph: Rewrite to allow multiple users Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 01/14] fgraph: Create a fgraph.c file to store function graph infrastructure Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 02/14] fgraph: Have set_graph_notrace only affect function_graph tracer Steven Rostedt
2018-11-23 0:01 ` Namhyung Kim [this message]
2018-11-23 17:37 ` Steven Rostedt
2018-11-24 5:49 ` Namhyung Kim
2018-11-24 18:41 ` Steven Rostedt
2018-11-26 4:54 ` Namhyung Kim
2018-11-22 1:27 ` [RFC][PATCH 03/14] arm64: function_graph: Remove use of FTRACE_NOTRACE_DEPTH Steven Rostedt
2018-11-27 19:31 ` Will Deacon
2018-11-27 19:50 ` Steven Rostedt
2018-12-05 21:50 ` [PATCH 03/14 v2] " Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 04/14] function_graph: Remove the " Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 05/14] ftrace: Create new ftrace-internal.h header Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 06/14] fgraph: Move function graph specific code into fgraph.c Steven Rostedt
2018-11-23 6:11 ` Joel Fernandes
2018-11-23 17:58 ` Steven Rostedt
2018-11-23 18:11 ` Steven Rostedt
2018-11-23 22:13 ` Joel Fernandes
2018-11-26 7:25 ` Masami Hiramatsu
2018-11-22 1:27 ` [RFC][PATCH 07/14] fgraph: Add new fgraph_ops structure to enable function graph hooks Steven Rostedt
2018-11-23 2:59 ` Joel Fernandes
2018-11-23 18:25 ` Steven Rostedt
2018-11-26 11:30 ` Masami Hiramatsu
2018-11-26 21:06 ` Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 08/14] function_graph: Remove unused task_curr_ret_stack() Steven Rostedt
2018-11-26 7:40 ` Masami Hiramatsu
2018-11-26 21:26 ` Steven Rostedt
2018-11-26 10:02 ` Joey Pabalinas
2018-11-26 21:27 ` Steven Rostedt
2018-11-26 21:37 ` Joey Pabalinas
2018-11-22 1:27 ` [RFC][PATCH 09/14] function_graph: Move ftrace_graph_get_addr() to fgraph.c Steven Rostedt
2018-11-23 3:13 ` Joel Fernandes
2018-11-23 19:25 ` Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 10/14] function_graph: Have profiler use new helper ftrace_graph_get_ret_stack() Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 11/14] function_graph: Convert ret_stack to a series of longs Steven Rostedt
2018-11-24 5:31 ` Joel Fernandes
2018-11-26 16:07 ` Masami Hiramatsu
2018-11-26 16:26 ` Steven Rostedt
2018-11-28 1:38 ` Joel Fernandes
2018-11-26 21:31 ` Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 12/14] function_graph: Add an array structure that will allow multiple callbacks Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 13/14] function_graph: Allow multiple users to attach to function graph Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 14/14] function_graph: Allow for more than one callback to be registered Steven Rostedt
2018-11-22 10:08 ` [RFC][PATCH 00/14] function_graph: Rewrite to allow multiple users Peter Zijlstra
2018-11-22 12:46 ` Steven Rostedt
2018-11-22 13:42 ` Peter Zijlstra
2018-11-26 9:21 ` Masami Hiramatsu
2018-11-26 16:32 ` Steven Rostedt
2018-11-29 14:29 ` Masami Hiramatsu
2018-11-29 16:46 ` Steven Rostedt
2018-11-30 2:26 ` Masami Hiramatsu
2018-11-30 3:24 ` Steven Rostedt
2018-11-30 14:11 ` Masami Hiramatsu
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