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[PATCH 02/32] tracing: Reimplement log2

From Tom Zanussi <tom.zanussi@linux.intel.com>
Newsgroups linux.kernel
Subject [PATCH 02/32] tracing: Reimplement log2
Date 2017-06-27 01:00 +0200
Message-ID <tWL97-8u4-3@gated-at.bofh.it> (permalink)
References <tWKZs-8nP-19@gated-at.bofh.it>
Organization linux.* mail to news gateway

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log2 as currently implemented applies only to u64 trace_event_field
derived fields, and assumes that anything it's applied to is a u64
field.

To prepare for synthetic fields like latencies, log2 should be
applicable to those as well, so take the opportunity now to fix the
current problems as well as expand to more general uses.

log2 should be thought of as a chaining function rather than a field
type.  To enable this as well as possible future function
implementations, add a hist_field operand array into the hist_field
definition for this purpose, and make use of it to implement the log2
'function'.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace_events_hist.c | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 91ffc39..7b55956 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -28,12 +28,16 @@
 
 typedef u64 (*hist_field_fn_t) (struct hist_field *field, void *event);
 
+#define HIST_FIELD_OPERANDS_MAX	2
+
 struct hist_field {
 	struct ftrace_event_field	*field;
 	unsigned long			flags;
 	hist_field_fn_t			fn;
 	unsigned int			size;
 	unsigned int			offset;
+	unsigned int                    is_signed;
+	struct hist_field		*operands[HIST_FIELD_OPERANDS_MAX];
 };
 
 static u64 hist_field_none(struct hist_field *field, void *event)
@@ -71,7 +75,9 @@ static u64 hist_field_pstring(struct hist_field *hist_field, void *event)
 
 static u64 hist_field_log2(struct hist_field *hist_field, void *event)
 {
-	u64 val = *(u64 *)(event + hist_field->field->offset);
+	struct hist_field *operand = hist_field->operands[0];
+
+	u64 val = operand->fn(operand, event);
 
 	return (u64) ilog2(roundup_pow_of_two(val));
 }
@@ -156,6 +162,8 @@ static const char *hist_field_name(struct hist_field *field,
 
 	if (field->field)
 		field_name = field->field->name;
+	else if (field->flags & HIST_FIELD_FL_LOG2)
+		field_name = hist_field_name(field->operands[0], ++level);
 
 	if (field_name == NULL)
 		field_name = "";
@@ -357,8 +365,20 @@ static void hist_trigger_elt_comm_init(struct tracing_map_elt *elt)
 	.elt_init	= hist_trigger_elt_comm_init,
 };
 
-static void destroy_hist_field(struct hist_field *hist_field)
+static void destroy_hist_field(struct hist_field *hist_field,
+			       unsigned int level)
 {
+	unsigned int i;
+
+	if (level > 2)
+		return;
+
+	if (!hist_field)
+		return;
+
+	for (i = 0; i < HIST_FIELD_OPERANDS_MAX; i++)
+		destroy_hist_field(hist_field->operands[i], ++level);
+
 	kfree(hist_field);
 }
 
@@ -385,7 +405,10 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
 	}
 
 	if (flags & HIST_FIELD_FL_LOG2) {
+		unsigned long fl = flags & ~HIST_FIELD_FL_LOG2;
 		hist_field->fn = hist_field_log2;
+		hist_field->operands[0] = create_hist_field(field, fl);
+		hist_field->size = hist_field->operands[0]->size;
 		goto out;
 	}
 
@@ -405,7 +428,7 @@ static struct hist_field *create_hist_field(struct ftrace_event_field *field,
 		hist_field->fn = select_value_fn(field->size,
 						 field->is_signed);
 		if (!hist_field->fn) {
-			destroy_hist_field(hist_field);
+			destroy_hist_field(hist_field, 0);
 			return NULL;
 		}
 	}
@@ -422,7 +445,7 @@ static void destroy_hist_fields(struct hist_trigger_data *hist_data)
 
 	for (i = 0; i < TRACING_MAP_FIELDS_MAX; i++) {
 		if (hist_data->fields[i]) {
-			destroy_hist_field(hist_data->fields[i]);
+			destroy_hist_field(hist_data->fields[i], 0);
 			hist_data->fields[i] = NULL;
 		}
 	}
-- 
1.9.3

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Thread

[PATCH 00/32]  tracing: Inter-event (e.g. latency) support Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 00:50 +0200
  [PATCH 17/32] tracing: Account for variables in named trigger compatibility Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 02/32] tracing: Reimplement log2 Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 10/32] tracing: Add NO_DISCARD event file flag Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 11/32] tracing: Add post-trigger flag to hist trigger command Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 19/32] tracing: Add variable reference handling to hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 29/32] tracing: Add 'last error' error facility for hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 04/32] ring-buffer: Redefine the unimplemented RINGBUF_TIME_TIME_STAMP Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
    Re: [PATCH 04/32] ring-buffer: Redefine the unimplemented RINGBUF_TIME_TIME_STAMP "Joel Fernandes (Google)" <joel.opensrc@gmail.com> - 2017-07-02 11:00 +0200
  [PATCH 06/32] tracing: Add ring buffer event param to hist field functions Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 16/32] tracing: Add variable support to hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 20/32] tracing: Add support for dynamic tracepoints Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 24/32] tracing: Add 'onmax' hist trigger action support Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 03/32] ring-buffer: Add interface for setting absolute time stamps Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 13/32] tracing: Add per-element variable support to tracing_map Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 09/32] tracing: Make traceprobe parsing code reusable Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 28/32] tracing: Add hist trigger support for variable reference aliases Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 32/32] tracing: Add a clock attribute for hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 25/32] tracing: Allow whitespace to surround hist trigger filter Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 05/32] tracing: Give event triggers access to ring_buffer_event Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 21/32] tracing: Add hist trigger action hook Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 07/32] tracing: Increase tracing map KEYS_MAX size Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 30/32] tracing: Add inter-event hist trigger Documentation Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 31/32] tracing: Make tracing_set_clock() non-static Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 22/32] tracing: Add support for 'synthetic' events Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 12/32] tracing: Add hist trigger timestamp support Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 18/32] tracing: Add simple expression support to hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 08/32] tracing: Break out hist trigger assignment parsing Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 15/32] tracing: Add usecs modifier for hist trigger timestamps Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 23/32] tracing: Add 'onmatch' hist trigger action support Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 14/32] tracing: Add hist_data member to hist_field Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 26/32] tracing: Make duplicate count from tracing_map available Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 01/32] tracing: Add hist_field_name() accessor Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  [PATCH 27/32] tracing: Add cpu field for hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-27 01:00 +0200
  Re: [PATCH 00/32]  tracing: Inter-event (e.g. latency) support Steven Rostedt <rostedt@goodmis.org> - 2017-06-27 17:10 +0200
  Re: [PATCH 00/32]  tracing: Inter-event (e.g. latency) support Masami Hiramatsu <mhiramat@kernel.org> - 2017-06-28 16:30 +0200
    Re: [PATCH 00/32]  tracing: Inter-event (e.g. latency) support Tom Zanussi <tom.zanussi@linux.intel.com> - 2017-06-28 21:20 +0200
  Re: [PATCH 00/32] tracing: Inter-event (e.g. latency) support "Joel Fernandes (Google)" <joel.opensrc@gmail.com> - 2017-07-01 09:10 +0200

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