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, 100 insertions, 0 deletions

diff --git a/arch/m68k/sun3/sun3ints.c b/arch/m68k/sun3/sun3ints.c
new file mode 100644
index 000000000..32eaf55f8
--- /dev/null
+++ b/arch/m68k/sun3/sun3ints.c
@@ -0,0 +1,100 @@
+ /*
+ * linux/arch/m68k/sun3/sun3ints.c -- Sun-3(x) Linux interrupt handling code
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/kernel_stat.h>
+#include <linux/interrupt.h>
+#include <asm/intersil.h>
+#include <asm/oplib.h>
+#include <asm/sun3ints.h>
+#include <asm/irq_regs.h>
+#include <linux/seq_file.h>
+
+#include "sun3.h"
+
+void sun3_disable_interrupts(void)
+{
+	sun3_disable_irq(0);
+}
+
+void sun3_enable_interrupts(void)
+{
+	sun3_enable_irq(0);
+}
+
+static unsigned char led_pattern[8] = {
+	(u8)~(0x80), (u8)~(0x01),
+	(u8)~(0x40), (u8)~(0x02),
+	(u8)~(0x20), (u8)~(0x04),
+	(u8)~(0x10), (u8)~(0x08)
+};
+
+volatile unsigned char* sun3_intreg;
+
+void sun3_enable_irq(unsigned int irq)
+{
+	*sun3_intreg |=  (1 << irq);
+}
+
+void sun3_disable_irq(unsigned int irq)
+{
+	*sun3_intreg &= ~(1 << irq);
+}
+
+static irqreturn_t sun3_int7(int irq, void *dev_id)
+{
+	unsigned int cnt;
+
+	cnt = kstat_irqs_cpu(irq, 0);
+	if (!(cnt % 2000))
+		sun3_leds(led_pattern[cnt % 16000 / 2000]);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t sun3_int5(int irq, void *dev_id)
+{
+	unsigned long flags;
+	unsigned int cnt;
+
+	local_irq_save(flags);
+#ifdef CONFIG_SUN3
+	intersil_clear();
+#endif
+	sun3_disable_irq(5);
+	sun3_enable_irq(5);
+#ifdef CONFIG_SUN3
+	intersil_clear();
+#endif
+	legacy_timer_tick(1);
+	cnt = kstat_irqs_cpu(irq, 0);
+	if (!(cnt % 20))
+		sun3_leds(led_pattern[cnt % 160 / 20]);
+	local_irq_restore(flags);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t sun3_vec255(int irq, void *dev_id)
+{
+	return IRQ_HANDLED;
+}
+
+void __init sun3_init_IRQ(void)
+{
+	*sun3_intreg = 1;
+
+	m68k_setup_user_interrupt(VEC_USER, 128);
+
+	if (request_irq(IRQ_AUTO_5, sun3_int5, 0, "clock", NULL))
+		pr_err("Couldn't register %s interrupt\n", "int5");
+	if (request_irq(IRQ_AUTO_7, sun3_int7, 0, "nmi", NULL))
+		pr_err("Couldn't register %s interrupt\n", "int7");
+	if (request_irq(IRQ_USER+127, sun3_vec255, 0, "vec255", NULL))
+		pr_err("Couldn't register %s interrupt\n", "vec255");
+}