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, 56 insertions, 0 deletions

diff --git a/drivers/spi/internals.h b/drivers/spi/internals.h
new file mode 100644
index 000000000..c56c190b0
--- /dev/null
+++ b/drivers/spi/internals.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2018 Exceet Electronics GmbH
+ * Copyright (C) 2018 Bootlin
+ *
+ * Author: Boris Brezillon <boris.brezillon@bootlin.com>
+ *
+ * Helpers needed by the SPI core and its tests. Should not be used outside
+ * drivers/spi/.
+ */
+
+#ifndef __LINUX_SPI_INTERNALS_H
+#define __LINUX_SPI_INTERNALS_H
+
+#include <linux/device.h>
+#include <linux/dma-direction.h>
+#include <linux/scatterlist.h>
+#include <linux/spi/spi.h>
+
+void spi_flush_queue(struct spi_controller *ctrl);
+
+#ifdef CONFIG_HAS_DMA
+#if IS_ENABLED(CONFIG_KUNIT)
+int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg);
+int __spi_unmap_msg(struct spi_controller *ctlr, struct spi_message *msg);
+#endif
+
+int spi_map_buf(struct spi_controller *ctlr, struct device *dev,
+		struct sg_table *sgt, void *buf, size_t len,
+		enum dma_data_direction dir);
+void spi_unmap_buf(struct spi_controller *ctlr, struct device *dev,
+		   struct sg_table *sgt, enum dma_data_direction dir);
+#else /* !CONFIG_HAS_DMA */
+static inline int spi_map_buf(struct spi_controller *ctlr, struct device *dev,
+			      struct sg_table *sgt, void *buf, size_t len,
+			      enum dma_data_direction dir)
+{
+	return -EINVAL;
+}
+
+static inline void spi_unmap_buf(struct spi_controller *ctlr,
+				 struct device *dev, struct sg_table *sgt,
+				 enum dma_data_direction dir)
+{
+}
+#endif /* CONFIG_HAS_DMA */
+
+static inline bool spi_xfer_is_dma_mapped(struct spi_controller *ctlr,
+					  struct spi_device *spi,
+					  struct spi_transfer *xfer)
+{
+	return ctlr->can_dma && ctlr->can_dma(ctlr, spi, xfer) &&
+	       (xfer->tx_sg_mapped || xfer->rx_sg_mapped);
+}
+
+#endif /* __LINUX_SPI_INTERNALS_H */