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, 30 insertions, 0 deletions

diff --git a/scripts/extract-fwblobs b/scripts/extract-fwblobs
new file mode 100755
index 000000000..53729124e
--- /dev/null
+++ b/scripts/extract-fwblobs
@@ -0,0 +1,30 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# -----------------------------------------------------------------------------
+# Extracts the vmlinux built-in firmware blobs - requires a non-stripped image
+# -----------------------------------------------------------------------------
+
+if [ -z "$1" ]; then
+	echo "Must provide a non-stripped vmlinux as argument"
+	exit 1
+fi
+
+read -r RD_ADDR_HEX RD_OFF_HEX <<< "$( readelf -SW "$1" |\
+grep -w rodata | awk '{print "0x"$5" 0x"$6}' )"
+
+FW_SYMS="$(readelf -sW "$1" |\
+awk -n '/fw_end/ { end=$2 ; print name " 0x" start " 0x" end; } { start=$2; name=$8; }')"
+
+while IFS= read -r entry; do
+	read -r FW_NAME FW_ADDR_ST_HEX FW_ADDR_END_HEX <<< "$entry"
+
+	# Notice kernel prepends _fw_ and appends _bin to the FW name
+	# in rodata; hence we hereby filter that out.
+	FW_NAME=${FW_NAME:4:-4}
+
+	FW_OFFSET="$(printf "%d" $((FW_ADDR_ST_HEX - RD_ADDR_HEX + RD_OFF_HEX)))"
+	FW_SIZE="$(printf "%d" $((FW_ADDR_END_HEX - FW_ADDR_ST_HEX)))"
+
+	dd if="$1" of="./${FW_NAME}" bs="${FW_SIZE}" count=1 iflag=skip_bytes skip="${FW_OFFSET}"
+done <<< "${FW_SYMS}"