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, 69 insertions, 0 deletions

diff --git a/include/media/videobuf2-dvb.h b/include/media/videobuf2-dvb.h
new file mode 100644
index 000000000..2d577b945
--- /dev/null
+++ b/include/media/videobuf2-dvb.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _VIDEOBUF2_DVB_H_
+#define	_VIDEOBUF2_DVB_H_
+
+#include <media/dvbdev.h>
+#include <media/dmxdev.h>
+#include <media/dvb_demux.h>
+#include <media/dvb_net.h>
+#include <media/dvb_frontend.h>
+#include <media/videobuf2-v4l2.h>
+
+/* We don't actually need to include media-device.h here */
+struct media_device;
+
+/*
+ * TODO: This header file should be replaced with videobuf2-core.h
+ * Currently, vb2_thread is not a stuff of videobuf2-core,
+ * since vb2_thread has many dependencies on videobuf2-v4l2.
+ */
+
+struct vb2_dvb {
+	/* filling that the job of the driver */
+	char			*name;
+	struct dvb_frontend	*frontend;
+	struct vb2_queue	dvbq;
+
+	/* vb2-dvb state info */
+	struct mutex		lock;
+	int			nfeeds;
+
+	/* vb2_dvb_(un)register manages this */
+	struct dvb_demux	demux;
+	struct dmxdev		dmxdev;
+	struct dmx_frontend	fe_hw;
+	struct dmx_frontend	fe_mem;
+	struct dvb_net		net;
+};
+
+struct vb2_dvb_frontend {
+	struct list_head felist;
+	int id;
+	struct vb2_dvb dvb;
+};
+
+struct vb2_dvb_frontends {
+	struct list_head felist;
+	struct mutex lock;
+	struct dvb_adapter adapter;
+	int active_fe_id; /* Indicates which frontend in the felist is in use */
+	int gate; /* Frontend with gate control 0=!MFE,1=fe0,2=fe1 etc */
+};
+
+int vb2_dvb_register_bus(struct vb2_dvb_frontends *f,
+			 struct module *module,
+			 void *adapter_priv,
+			 struct device *device,
+			 struct media_device *mdev,
+			 short *adapter_nr,
+			 int mfe_shared);
+
+void vb2_dvb_unregister_bus(struct vb2_dvb_frontends *f);
+
+struct vb2_dvb_frontend *vb2_dvb_alloc_frontend(struct vb2_dvb_frontends *f, int id);
+void vb2_dvb_dealloc_frontends(struct vb2_dvb_frontends *f);
+
+struct vb2_dvb_frontend *vb2_dvb_get_frontend(struct vb2_dvb_frontends *f, int id);
+int vb2_dvb_find_frontend(struct vb2_dvb_frontends *f, struct dvb_frontend *p);
+
+#endif			/* _VIDEOBUF2_DVB_H_ */