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, 80 insertions, 0 deletions

diff --git a/drivers/i3c/internals.h b/drivers/i3c/internals.h
new file mode 100644
index 000000000..86a36b951
--- /dev/null
+++ b/drivers/i3c/internals.h
@@ -0,0 +1,80 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2018 Cadence Design Systems Inc.
+ *
+ * Author: Boris Brezillon <boris.brezillon@bootlin.com>
+ */
+
+#ifndef I3C_INTERNALS_H
+#define I3C_INTERNALS_H
+
+#include <linux/i3c/master.h>
+#include <linux/io.h>
+
+int __must_check i3c_bus_rpm_get(struct i3c_bus *bus);
+void i3c_bus_rpm_put(struct i3c_bus *bus);
+bool i3c_bus_rpm_ibi_allowed(struct i3c_bus *bus);
+
+void i3c_bus_normaluse_lock(struct i3c_bus *bus);
+void i3c_bus_normaluse_unlock(struct i3c_bus *bus);
+
+int i3c_dev_setdasa_locked(struct i3c_dev_desc *dev);
+int i3c_dev_do_xfers_locked(struct i3c_dev_desc *dev,
+			    struct i3c_xfer *xfers,
+			    int nxfers, enum i3c_xfer_mode mode);
+int i3c_dev_disable_ibi_locked(struct i3c_dev_desc *dev);
+int i3c_dev_enable_ibi_locked(struct i3c_dev_desc *dev);
+int i3c_dev_request_ibi_locked(struct i3c_dev_desc *dev,
+			       const struct i3c_ibi_setup *req);
+void i3c_dev_free_ibi_locked(struct i3c_dev_desc *dev);
+
+/**
+ * i3c_writel_fifo - Write data buffer to 32bit FIFO
+ * @addr: FIFO Address to write to
+ * @buf: Pointer to the data bytes to write
+ * @nbytes: Number of bytes to write
+ */
+static inline void i3c_writel_fifo(void __iomem *addr, const void *buf,
+				   int nbytes)
+{
+	writesl(addr, buf, nbytes / 4);
+	if (nbytes & 3) {
+		u32 tmp = 0;
+
+		memcpy(&tmp, buf + (nbytes & ~3), nbytes & 3);
+		/*
+		 * writesl() instead of writel() to keep FIFO
+		 * byteorder on big-endian targets
+		 */
+		writesl(addr, &tmp, 1);
+	}
+}
+
+/**
+ * i3c_readl_fifo - Read data buffer from 32bit FIFO
+ * @addr: FIFO Address to read from
+ * @buf: Pointer to the buffer to store read bytes
+ * @nbytes: Number of bytes to read
+ */
+static inline void i3c_readl_fifo(const void __iomem *addr, void *buf,
+				  int nbytes)
+{
+	readsl(addr, buf, nbytes / 4);
+	if (nbytes & 3) {
+		u32 tmp;
+
+		/*
+		 * readsl() instead of readl() to keep FIFO
+		 * byteorder on big-endian targets
+		 */
+		readsl(addr, &tmp, 1);
+		memcpy(buf + (nbytes & ~3), &tmp, nbytes & 3);
+	}
+}
+
+static inline struct i3c_master_controller *i3c_bus_to_i3c_master(struct i3c_bus *i3cbus)
+{
+	return container_of(i3cbus, struct i3c_master_controller, bus);
+}
+
+#endif /* I3C_INTERNAL_H */