linux-kernel - [PATCH] drm/amdgpu: Fix error handling in amdgpu_atpx

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Message-Id: <20251121014415.37964-1-make24@iscas.ac.cn>
Date: Fri, 21 Nov 2025 09:44:15 +0800
From: Ma Ke <make24@...as.ac.cn>
To: alexander.deucher@....com,
	christian.koenig@....com,
	airlied@...il.com,
	simona@...ll.ch,
	make24@...as.ac.cn,
	evan.quan@....com
Cc: amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org,
	stable@...r.kernel.org
Subject: [PATCH] drm/amdgpu: Fix error handling in amdgpu_atpx_detect

amdgpu_atpx_detect() uses pci_get_class() in two while loops to
iterate through VGA and OTHER display class PCI devices. Each call to
pci_get_class() increments the reference count of the returned PCI
device. However, after the loops complete, there are no corresponding
pci_dev_put() to decrement these reference counts.

Add pci_dev_put() after each while loop to release reference counts
held by the last devices found in each class.

Found by code review.

Cc: stable@...r.kernel.org
Fixes: 5d30ed3c2c74 ("Revert "drm/amdgpu: simplify ATPX detection"")
Signed-off-by: Ma Ke <make24@...as.ac.cn>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c
index 3893e6fc2f03..9eb776a2e8bb 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c
@@ -617,6 +617,9 @@ static bool amdgpu_atpx_detect(void)
 		amdgpu_atpx_get_quirks(pdev);
 	}
 
+	pci_dev_put(pdev);
+	pdev = NULL;
+
 	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_OTHER << 8, pdev)) != NULL) {
 		vga_count++;
 
@@ -627,6 +630,8 @@ static bool amdgpu_atpx_detect(void)
 		amdgpu_atpx_get_quirks(pdev);
 	}
 
+	pci_dev_put(pdev);
+
 	if (has_atpx && vga_count == 2) {
 		acpi_get_name(amdgpu_atpx_priv.atpx.handle, ACPI_FULL_PATHNAME, &buffer);
 		pr_info("vga_switcheroo: detected switching method %s handle\n",
-- 
2.17.1