linux-kernel - [PATCH 1/4] oprofile: Handle initialisation failure more gracefully

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Message-Id: <442a16796990290ca3ebaaa3d0ab317e7b0a30a5.1282848651.git.matt@console-pimps.org>
Date:	Thu, 26 Aug 2010 20:09:16 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	linux-kernel@...r.kernel.org
Cc:	Robert Richter <robert.richter@....com>,
	Will Deacon <will.deacon@....com>,
	Paul Mundt <lethal@...ux-sh.org>,
	Russell King <linux@....linux.org.uk>,
	linux-arm-kernel@...ts.infradead.org, linux-sh@...r.kernel.org,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	linux-arch@...r.kernel.org
Subject: [PATCH 1/4] oprofile: Handle initialisation failure more gracefully

From: Will Deacon <will.deacon@....com>

The current implementation is not entirely safe in the case that
oprofile_arch_init() fails. We need to make sure that we always call
exit_driverfs() if we've called init_driverfs(). Also, avoid a potential
double free when freeing 'counter_config', e.g. don't free
'counter_config' in both oprofile_arch_init() and oprofile_arch_exit().

Signed-off-by: Will Deacon <will.deacon@....com>
---
 arch/arm/oprofile/common.c |   15 ++++++++-------
 1 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/arm/oprofile/common.c b/arch/arm/oprofile/common.c
index 0691176..482779c 100644
--- a/arch/arm/oprofile/common.c
+++ b/arch/arm/oprofile/common.c
@@ -275,10 +275,12 @@ out:
 	return ret;
 }
 
-static void  exit_driverfs(void)
+static void exit_driverfs(void)
 {
-	platform_device_unregister(oprofile_pdev);
-	platform_driver_unregister(&oprofile_driver);
+	if (!IS_ERR_OR_NULL(oprofile_pdev)) {
+		platform_device_unregister(oprofile_pdev);
+		platform_driver_unregister(&oprofile_driver);
+	}
 }
 #else
 static int __init init_driverfs(void) { return 0; }
@@ -363,10 +365,8 @@ int __init oprofile_arch_init(struct oprofile_operations *ops)
 	}
 
 	ret = init_driverfs();
-	if (ret) {
-		kfree(counter_config);
+	if (ret)
 		return ret;
-	}
 
 	for_each_possible_cpu(cpu) {
 		perf_events[cpu] = kcalloc(perf_num_counters,
@@ -401,8 +401,9 @@ void oprofile_arch_exit(void)
 	int cpu, id;
 	struct perf_event *event;
 
+	exit_driverfs();
+
 	if (*perf_events) {
-		exit_driverfs();
 		for_each_possible_cpu(cpu) {
 			for (id = 0; id < perf_num_counters; ++id) {
 				event = perf_events[cpu][id];
-- 
1.7.1

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