linux-kernel - [PATCH v2] perf/imx_ddr: Fix cpu hotplug state cleanup

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Date:   Tue, 14 Jan 2020 22:25:46 +0200
From:   Leonard Crestez <leonard.crestez@....com>
To:     Joakim Zhang <qiangqing.zhang@....com>,
        Will Deacon <will@...nel.org>
Cc:     Frank Li <frank.li@....com>, Mark Rutland <mark.rutland@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] perf/imx_ddr: Fix cpu hotplug state cleanup

This driver allocates a dynamic cpu hotplug state but never releases it.
If reloaded in a loop it will quickly trigger a WARN message:

	"No more dynamic states available for CPU hotplug"

Fix by calling cpuhp_remove_multi_state on remove like several other
perf pmu drivers.

Also fix the cleanup logic on probe error paths: add the missing
cpuhp_remove_multi_state call and properly check the return value from
cpuhp_state_add_instant_nocalls.

Fixes: 9a66d36cc7ac ("drivers/perf: imx_ddr: Add DDR performance counter support to perf")
Signed-off-by: Leonard Crestez <leonard.crestez@....com>

---

Changes since v1:
* Handle cpuhp_state_add_instant_nocalls error with additional error
labels.
Link to v1: https://patchwork.kernel.org/patch/11302423/
---
 drivers/perf/fsl_imx8_ddr_perf.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/perf/fsl_imx8_ddr_perf.c b/drivers/perf/fsl_imx8_ddr_perf.c
index 3be61be1ba91..f144f1fd9b4d 100644
--- a/drivers/perf/fsl_imx8_ddr_perf.c
+++ b/drivers/perf/fsl_imx8_ddr_perf.c
@@ -631,17 +631,21 @@ static int ddr_perf_probe(struct platform_device *pdev)
 				      NULL,
 				      ddr_perf_offline_cpu);
 
 	if (ret < 0) {
 		dev_err(&pdev->dev, "cpuhp_setup_state_multi failed\n");
-		goto ddr_perf_err;
+		goto cpuhp_state_err;
 	}
 
 	pmu->cpuhp_state = ret;
 
 	/* Register the pmu instance for cpu hotplug */
-	cpuhp_state_add_instance_nocalls(pmu->cpuhp_state, &pmu->node);
+	ret = cpuhp_state_add_instance_nocalls(pmu->cpuhp_state, &pmu->node);
+	if (ret) {
+		dev_err(&pdev->dev, "Error %d registering hotplug\n", ret);
+		goto cpuhp_instance_err;
+	}
 
 	/* Request irq */
 	irq = of_irq_get(np, 0);
 	if (irq < 0) {
 		dev_err(&pdev->dev, "Failed to get irq: %d", irq);
@@ -672,23 +676,25 @@ static int ddr_perf_probe(struct platform_device *pdev)
 		goto ddr_perf_err;
 
 	return 0;
 
 ddr_perf_err:
-	if (pmu->cpuhp_state)
-		cpuhp_state_remove_instance_nocalls(pmu->cpuhp_state, &pmu->node);
-
+	cpuhp_state_remove_instance_nocalls(pmu->cpuhp_state, &pmu->node);
+cpuhp_instance_err:
+	cpuhp_remove_multi_state(pmu->cpuhp_state);
+cpuhp_state_err:
 	ida_simple_remove(&ddr_ida, pmu->id);
 	dev_warn(&pdev->dev, "i.MX8 DDR Perf PMU failed (%d), disabled\n", ret);
 	return ret;
 }
 
 static int ddr_perf_remove(struct platform_device *pdev)
 {
 	struct ddr_pmu *pmu = platform_get_drvdata(pdev);
 
 	cpuhp_state_remove_instance_nocalls(pmu->cpuhp_state, &pmu->node);
+	cpuhp_remove_multi_state(pmu->cpuhp_state);
 	irq_set_affinity_hint(pmu->irq, NULL);
 
 	perf_pmu_unregister(&pmu->pmu);
 
 	ida_simple_remove(&ddr_ida, pmu->id);
-- 
2.17.1