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, 49 insertions, 0 deletions

diff --git a/drivers/gpib/include/amcc5920.h b/drivers/gpib/include/amcc5920.h
new file mode 100644
index 000000000..7a88bd282
--- /dev/null
+++ b/drivers/gpib/include/amcc5920.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/***************************************************************************
+ *  Header for amcc5920 pci chip
+ *
+ *   copyright		  : (C) 2002 by Frank Mori Hess
+ ***************************************************************************/
+
+// plx pci chip registers and bits
+enum amcc_registers {
+	AMCC_INTCS_REG = 0x38,
+	AMCC_PASS_THRU_REG	= 0x60,
+};
+
+enum amcc_incsr_bits {
+	AMCC_ADDON_INTR_ENABLE_BIT = 0x2000,
+	AMCC_ADDON_INTR_ACTIVE_BIT = 0x400000,
+	AMCC_INTR_ACTIVE_BIT = 0x800000,
+};
+
+static const int bits_per_region = 8;
+
+static inline uint32_t amcc_wait_state_bits(unsigned int region, unsigned int num_wait_states)
+{
+	return (num_wait_states & 0x7) << (--region * bits_per_region);
+};
+
+enum amcc_prefetch_bits {
+	PREFETCH_DISABLED = 0x0,
+	PREFETCH_SMALL = 0x8,
+	PREFETCH_MEDIUM = 0x10,
+	PREFETCH_LARGE = 0x18,
+};
+
+static inline uint32_t amcc_prefetch_bits(unsigned int region, enum amcc_prefetch_bits prefetch)
+{
+	return prefetch << (--region * bits_per_region);
+};
+
+static inline uint32_t amcc_PTADR_mode_bit(unsigned int region)
+{
+	return 0x80 << (--region * bits_per_region);
+};
+
+static inline uint32_t amcc_disable_write_fifo_bit(unsigned int region)
+{
+	return 0x20 << (--region * bits_per_region);
+};
+