x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 44 insertions, 0 deletions

diff --git a/drivers/video/videomode.c b/drivers/video/videomode.c
new file mode 100644
index 000000000..2ecf80c08
--- /dev/null
+++ b/drivers/video/videomode.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * generic display timing functions
+ *
+ * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>, Pengutronix
+ */
+
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <video/display_timing.h>
+#include <video/videomode.h>
+
+void videomode_from_timing(const struct display_timing *dt,
+			  struct videomode *vm)
+{
+	vm->pixelclock = dt->pixelclock.typ;
+	vm->hactive = dt->hactive.typ;
+	vm->hfront_porch = dt->hfront_porch.typ;
+	vm->hback_porch = dt->hback_porch.typ;
+	vm->hsync_len = dt->hsync_len.typ;
+
+	vm->vactive = dt->vactive.typ;
+	vm->vfront_porch = dt->vfront_porch.typ;
+	vm->vback_porch = dt->vback_porch.typ;
+	vm->vsync_len = dt->vsync_len.typ;
+
+	vm->flags = dt->flags;
+}
+EXPORT_SYMBOL_GPL(videomode_from_timing);
+
+int videomode_from_timings(const struct display_timings *disp,
+			  struct videomode *vm, unsigned int index)
+{
+	struct display_timing *dt;
+
+	dt = display_timings_get(disp, index);
+	if (!dt)
+		return -EINVAL;
+
+	videomode_from_timing(dt, vm);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(videomode_from_timings);