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Date:   Wed, 28 Mar 2018 14:48:15 +0300
From:   Dan Carpenter <dan.carpenter@oracle.com>
To:     Steven Rostedt <rostedt@goodmis.org>,
        Tom Zanussi <tom.zanussi@linux.intel.com>
Cc:     Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        kernel-janitors@vger.kernel.org
Subject: [PATCH] tracing: Uninitialized variable in
 create_tracing_map_fields()
Message-ID: <20180328114815.GC29050@mwanda>
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Smatch complains that idx can be used uninitialized when we check if
(idx < 0).  It has to be the first iteration through the loop and the
HIST_FIELD_FL_STACKTRACE bit has to be clear and the HIST_FIELD_FL_VAR
bit has to be set to reach the bug.

Fixes: 30350d65ac56 ("tracing: Add variable support to hist triggers")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 4f027642ceef..6aceee287d07 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -4411,7 +4411,7 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
 	struct tracing_map *map = hist_data->map;
 	struct ftrace_event_field *field;
 	struct hist_field *hist_field;
-	int i, idx;
+	int i, idx = 0;
 
 	for_each_hist_field(i, hist_data) {
 		hist_field = hist_data->fields[i];