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, 40 insertions, 0 deletions

diff --git a/drivers/clocksource/timer-versatile.c b/drivers/clocksource/timer-versatile.c
new file mode 100644
index 000000000..f5d017b31
--- /dev/null
+++ b/drivers/clocksource/timer-versatile.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright (C) 2014 ARM Limited
+ */
+
+#include <linux/clocksource.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/sched_clock.h>
+
+#define SYS_24MHZ 0x05c
+
+static void __iomem *versatile_sys_24mhz;
+
+static u64 notrace versatile_sys_24mhz_read(void)
+{
+	return readl(versatile_sys_24mhz);
+}
+
+static int __init versatile_sched_clock_init(struct device_node *node)
+{
+	void __iomem *base = of_iomap(node, 0);
+
+	of_node_clear_flag(node, OF_POPULATED);
+
+	if (!base)
+		return -ENXIO;
+
+	versatile_sys_24mhz = base + SYS_24MHZ;
+
+	sched_clock_register(versatile_sys_24mhz_read, 32, 24000000);
+
+	return 0;
+}
+TIMER_OF_DECLARE(vexpress, "arm,vexpress-sysreg",
+		       versatile_sched_clock_init);
+TIMER_OF_DECLARE(versatile, "arm,versatile-sysreg",
+		       versatile_sched_clock_init);