linux-kernel - [PATCH 2/3] drivers/perf: arm_pmu: Defer the setting of __oprofile_cpu

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Date:	Tue, 31 May 2016 12:41:22 +0100
From:	Julien Grall <julien.grall@....com>
To:	will.deacon@....com, mark.rutland@....com
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Julien Grall <julien.grall@....com>
Subject: [PATCH 2/3] drivers/perf: arm_pmu: Defer the setting of __oprofile_cpu_pmu

The global variable __oprofile_cpu_pmu is set before the PMU is fully
initialized. If an error occurs before the end of the initialization,
the PMU will be freed and the variable will contain an invalid pointer.

This will result in a kernel crash when perf will be used.

Fix it by moving the setting of __oprofile_cpu_pmu when the PMU is fully
initialized (i.e when it is no longer possible to fail).

Signed-off-by: Julien Grall <julien.grall@....com>
Acked-by: Mark Rutland <mark.rutland@....com>
---
 drivers/perf/arm_pmu.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 6401f0c..95614d2 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -992,9 +992,6 @@ int arm_pmu_device_probe(struct platform_device *pdev,
 
 	armpmu_init(pmu);
 
-	if (!__oprofile_cpu_pmu)
-		__oprofile_cpu_pmu = pmu;
-
 	pmu->plat_device = pdev;
 
 	if (node && (of_id = of_match_node(of_table, pdev->dev.of_node))) {
@@ -1030,6 +1027,9 @@ int arm_pmu_device_probe(struct platform_device *pdev,
 	if (ret)
 		goto out_destroy;
 
+	if (!__oprofile_cpu_pmu)
+		__oprofile_cpu_pmu = pmu;
+
 	pr_info("enabled with %s PMU driver, %d counters available\n",
 			pmu->name, pmu->num_events);
 
-- 
1.9.1