linux-kernel - [PATCH 4.19 56/92] tracing: Use hist triggers var_ref array to destroy var

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Message-Id: <20200128135816.390761744@linuxfoundation.org>
Date:   Tue, 28 Jan 2020 15:08:24 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Namhyung Kim <namhyung@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Tom Zanussi <tom.zanussi@...ux.intel.com>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Subject: [PATCH 4.19 56/92] tracing: Use hist triggers var_ref array to destroy var_refs

From: Tom Zanussi <tom.zanussi@...ux.intel.com>

commit 656fe2ba85e81d00e4447bf77b8da2be3c47acb2 upstream.

Since every var ref for a trigger has an entry in the var_ref[] array,
use that to destroy the var_refs, instead of piecemeal via the field
expressions.

This allows us to avoid having to keep and treat differently separate
lists for the action-related references, which future patches will
remove.

Link: http://lkml.kernel.org/r/fad1a164f0e257c158e70d6eadbf6c586e04b2a2.1545161087.git.tom.zanussi@linux.intel.com

Acked-by: Namhyung Kim <namhyung@...nel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@...nel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@...ux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/trace/trace_events_hist.c |   24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -2175,6 +2175,15 @@ static int contains_operator(char *str)
 	return field_op;
 }
 
+static void __destroy_hist_field(struct hist_field *hist_field)
+{
+	kfree(hist_field->var.name);
+	kfree(hist_field->name);
+	kfree(hist_field->type);
+
+	kfree(hist_field);
+}
+
 static void destroy_hist_field(struct hist_field *hist_field,
 			       unsigned int level)
 {
@@ -2186,14 +2195,13 @@ static void destroy_hist_field(struct hi
 	if (!hist_field)
 		return;
 
+	if (hist_field->flags & HIST_FIELD_FL_VAR_REF)
+		return; /* var refs will be destroyed separately */
+
 	for (i = 0; i < HIST_FIELD_OPERANDS_MAX; i++)
 		destroy_hist_field(hist_field->operands[i], level + 1);
 
-	kfree(hist_field->var.name);
-	kfree(hist_field->name);
-	kfree(hist_field->type);
-
-	kfree(hist_field);
+	__destroy_hist_field(hist_field);
 }
 
 static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
@@ -2320,6 +2328,12 @@ static void destroy_hist_fields(struct h
 			hist_data->fields[i] = NULL;
 		}
 	}
+
+	for (i = 0; i < hist_data->n_var_refs; i++) {
+		WARN_ON(!(hist_data->var_refs[i]->flags & HIST_FIELD_FL_VAR_REF));
+		__destroy_hist_field(hist_data->var_refs[i]);
+		hist_data->var_refs[i] = NULL;
+	}
 }
 
 static int init_var_ref(struct hist_field *ref_field,