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, 47 insertions, 0 deletions

diff --git a/drivers/parisc/gsc.h b/drivers/parisc/gsc.h
new file mode 100644
index 000000000..73cbd0bb1
--- /dev/null
+++ b/drivers/parisc/gsc.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * drivers/parisc/gsc.h
+ * Declarations for functions in gsc.c
+ * Copyright (c) 2000-2002 Helge Deller, Matthew Wilcox
+ */
+
+#include <linux/interrupt.h>
+#include <asm/hardware.h>
+#include <asm/parisc-device.h>
+
+#define OFFSET_IRR 0x0000   /* Interrupt request register */
+#define OFFSET_IMR 0x0004   /* Interrupt mask register */
+#define OFFSET_IPR 0x0008   /* Interrupt pending register */
+#define OFFSET_ICR 0x000C   /* Interrupt control register */
+#define OFFSET_IAR 0x0010   /* Interrupt address register */
+
+/* PA I/O Architected devices support at least 5 bits in the EIM register. */
+#define GSC_EIM_WIDTH 5
+
+struct gsc_irq {
+	unsigned long txn_addr;	/* IRQ "target" */
+	int txn_data;		/* HW "IRQ" */
+	int irq;		/* virtual IRQ */
+};
+
+struct gsc_asic {
+	struct parisc_device *gsc;
+	unsigned long hpa;
+	char *name;
+	int version;
+	int type;
+	int eim;
+	struct gsc_irq gsc_irq;
+	int global_irq[32];
+};
+
+int gsc_common_setup(struct parisc_device *parent, struct gsc_asic *gsc_asic);
+int gsc_alloc_irq(struct gsc_irq *dev);			/* dev needs an irq */
+int gsc_claim_irq(struct gsc_irq *dev, int irq);	/* dev needs this irq */
+int gsc_assign_irq(struct irq_chip *type, void *data);
+int gsc_find_local_irq(unsigned int irq, int *global_irq, int limit);
+void gsc_fixup_irqs(struct parisc_device *parent, void *ctrl,
+		void (*choose)(struct parisc_device *child, void *ctrl));
+void gsc_asic_assign_irq(struct gsc_asic *asic, int local_irq, int *irqp);
+
+irqreturn_t gsc_asic_intr(int irq, void *dev);