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, 72 insertions, 0 deletions

diff --git a/drivers/gpib/include/plx9050.h b/drivers/gpib/include/plx9050.h
new file mode 100644
index 000000000..c911b285a
--- /dev/null
+++ b/drivers/gpib/include/plx9050.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/***************************************************************************
+ *  Header for plx9050 pci chip
+ *    copyright            : (C) 2002 by Frank Mori Hess
+ ***************************************************************************/
+
+#ifndef _PLX9050_GPIB_H
+#define _PLX9050_GPIB_H
+
+// plx pci chip registers and bits
+enum {
+	PLX9050_INTCSR_REG = 0x4c,
+	PLX9050_CNTRL_REG = 0x50
+};
+
+enum plx9050_intcsr_bits {
+	PLX9050_LINTR1_EN_BIT = 0x1,
+	PLX9050_LINTR1_POLARITY_BIT = 0x2,
+	PLX9050_LINTR1_STATUS_BIT = 0x4,
+	PLX9050_LINTR2_EN_BIT = 0x8,
+	PLX9050_LINTR2_POLARITY_BIT = 0x10,
+	PLX9050_LINTR2_STATUS_BIT = 0x20,
+	PLX9050_PCI_INTR_EN_BIT = 0x40,
+	PLX9050_SOFT_INTR_BIT = 0x80,
+	PLX9050_LINTR1_SELECT_ENABLE_BIT = 0x100,	// 9052 extension
+	PLX9050_LINTR2_SELECT_ENABLE_BIT = 0x200,	// 9052 extension
+	PLX9050_LINTR1_EDGE_CLEAR_BIT = 0x400,		// 9052 extension
+	PLX9050_LINTR2_EDGE_CLEAR_BIT = 0x800,		// 9052 extension
+};
+
+enum plx9050_cntrl_bits {
+	PLX9050_WAITO_NOT_USER0_SELECT_BIT = 0x1,
+	PLX9050_USER0_OUTPUT_BIT = 0x2,
+	PLX9050_USER0_DATA_BIT = 0x4,
+	PLX9050_LLOCK_NOT_USER1_SELECT_BIT = 0x8,
+	PLX9050_USER1_OUTPUT_BIT = 0x10,
+	PLX9050_USER1_DATA_BIT = 0x20,
+	PLX9050_CS2_NOT_USER2_SELECT_BIT = 0x40,
+	PLX9050_USER2_OUTPUT_BIT = 0x80,
+	PLX9050_USER2_DATA_BIT = 0x100,
+	PLX9050_CS3_NOT_USER3_SELECT_BIT = 0x200,
+	PLX9050_USER3_OUTPUT_BIT = 0x400,
+	PLX9050_USER3_DATA_BIT = 0x800,
+	PLX9050_PCIBAR_ENABLE_MASK = 0x3000,
+	PLX9050_PCIBAR_MEMORY_AND_IO_ENABLE_BITS = 0x0,
+	PLX9050_PCIBAR_MEMORY_NO_IO_ENABLE_BITS = 0x1000,
+	PLX9050_PCIBAR_IO_NO_MEMORY_ENABLE_BITS = 0x2000,
+	PLX9050_PCIBAR_MEMORY_AND_IO_TOO_ENABLE_BITS = 0x3000,
+	PLX9050_PCI_READ_MODE_BIT = 0x4000,
+	PLX9050_PCI_READ_WITH_WRITE_FLUSH_MODE_BIT = 0x8000,
+	PLX9050_PCI_READ_NO_FLUSH_MODE_BIT = 0x10000,
+	PLX9050_PCI_READ_NO_WRITE_MODE_BIT = 0x20000,
+	PLX9050_PCI_WRITE_MODE_BIT = 0x40000,
+	PLX9050_PCI_RETRY_DELAY_MASK = 0x780000,
+	PLX9050_DIRECT_SLAVE_LOCK_ENABLE_BIT = 0x800000,
+	PLX9050_EEPROM_CLOCK_BIT = 0x1000000,
+	PLX9050_EEPROM_CHIP_SELECT_BIT = 0x2000000,
+	PLX9050_WRITE_TO_EEPROM_BIT = 0x4000000,
+	PLX9050_READ_EEPROM_DATA_BIT = 0x8000000,
+	PLX9050_EEPROM_VALID_BIT = 0x10000000,
+	PLX9050_RELOAD_CONFIG_REGISTERS_BIT = 0x20000000,
+	PLX9050_PCI_SOFTWARE_RESET_BIT = 0x40000000,
+	PLX9050_MASK_REVISION_BIT = 0x80000000
+};
+
+static inline unsigned int PLX9050_PCI_RETRY_DELAY_BITS(unsigned int clocks)
+{
+	return ((clocks / 8) << 19) & PLX9050_PCI_RETRY_DELAY_MASK;
+}
+
+#endif	// _PLX9050_GPIB_H