linux-kernel - [PATCH] drm/i915: Free the returned object of acpi_evaluate

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Date:   Mon, 6 Sep 2021 11:35:41 +0800
From:   Zenghui Yu <yuzenghui@...wei.com>
To:     <intel-gfx@...ts.freedesktop.org>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
CC:     <jani.nikula@...ux.intel.com>, <joonas.lahtinen@...ux.intel.com>,
        <rodrigo.vivi@...el.com>, <airlied@...ux.ie>, <daniel@...ll.ch>,
        <ville.syrjala@...ux.intel.com>, <tiwai@...e.de>,
        <wanghaibin.wang@...wei.com>, Zenghui Yu <yuzenghui@...wei.com>,
        "Kai-Heng Feng" <kai.heng.feng@...onical.com>
Subject: [PATCH] drm/i915: Free the returned object of acpi_evaluate_dsm()

As per the comment on top of acpi_evaluate_dsm():

| * Evaluate device's _DSM method with specified GUID, revision id and
| * function number. Caller needs to free the returned object.

We should free the returned object of acpi_evaluate_dsm() to avoid memory
leakage. Otherwise the kmemleak splat will be triggered at boot time (if we
compile kernel with CONFIG_DEBUG_TEST_DRIVER_REMOVE=y).

Fixes: 8e55f99c510f ("drm/i915: Invoke another _DSM to enable MUX on HP Workstation laptops")
Cc: Kai-Heng Feng <kai.heng.feng@...onical.com>
Signed-off-by: Zenghui Yu <yuzenghui@...wei.com>
---
 drivers/gpu/drm/i915/display/intel_acpi.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_acpi.c b/drivers/gpu/drm/i915/display/intel_acpi.c
index 7cfe91fc05f2..68abeaf2d7d4 100644
--- a/drivers/gpu/drm/i915/display/intel_acpi.c
+++ b/drivers/gpu/drm/i915/display/intel_acpi.c
@@ -186,13 +186,16 @@ void intel_dsm_get_bios_data_funcs_supported(struct drm_i915_private *i915)
 {
 	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
 	acpi_handle dhandle;
+	union acpi_object *obj;
 
 	dhandle = ACPI_HANDLE(&pdev->dev);
 	if (!dhandle)
 		return;
 
-	acpi_evaluate_dsm(dhandle, &intel_dsm_guid2, INTEL_DSM_REVISION_ID,
-			  INTEL_DSM_FN_GET_BIOS_DATA_FUNCS_SUPPORTED, NULL);
+	obj = acpi_evaluate_dsm(dhandle, &intel_dsm_guid2, INTEL_DSM_REVISION_ID,
+				INTEL_DSM_FN_GET_BIOS_DATA_FUNCS_SUPPORTED, NULL);
+	if (obj)
+		ACPI_FREE(obj);
 }
 
 /*
-- 
2.19.1