linux-kernel - [PATCH] tracing: fix referencing after memory freeing and refactors code

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Date:	Thu, 17 Oct 2013 22:44:56 -0300
From:	"Geyslan G. Bem" <geyslan@...il.com>
To:	unlisted-recipients:; (no To-header on input)
Cc:	kernel-br@...glegroups.com, "Geyslan G. Bem" <geyslan@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] tracing: fix referencing after memory freeing and refactors code

Restructures function logic conditions testing 'tracing_open_generic'
return before the others. It avoids: unnecessary trace_array_get and
kzalloc when tracing is disabled; and fix the possible 'dir'
assignment after freeing it.

Centralizes the exiting, ensuring the 'trace_array_put' on error,
in accordance to Coding Style, Chapter 7.

Signed-off-by: Geyslan G. Bem <geyslan@...il.com>
---
 kernel/trace/trace_events.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 368a4d5..8232362 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1108,26 +1108,28 @@ static int system_tr_open(struct inode *inode, struct file *filp)
 	struct trace_array *tr = inode->i_private;
 	int ret;
 
-	if (trace_array_get(tr) < 0)
-		return -ENODEV;
+	ret = tracing_open_generic(inode, filp);
+	if (ret)
+		return ret;
+
+	ret = trace_array_get(tr);
+	if (ret)
+		return ret;
 
 	/* Make a temporary dir that has no system but points to tr */
 	dir = kzalloc(sizeof(*dir), GFP_KERNEL);
 	if (!dir) {
-		trace_array_put(tr);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto err_dir;
 	}
 
 	dir->tr = tr;
 
-	ret = tracing_open_generic(inode, filp);
-	if (ret < 0) {
-		trace_array_put(tr);
-		kfree(dir);
-	}
-
 	filp->private_data = dir;
+	return 0;
 
+err_dir:
+	trace_array_put(tr);
 	return ret;
 }
 
-- 
1.8.4

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