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, 85 insertions, 0 deletions

diff --git a/drivers/reset/reset-sunxi.c b/drivers/reset/reset-sunxi.c
new file mode 100644
index 000000000..2f6df7707
--- /dev/null
+++ b/drivers/reset/reset-sunxi.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Allwinner SoCs Reset Controller driver
+ *
+ * Copyright 2013 Maxime Ripard
+ *
+ * Maxime Ripard <maxime.ripard@free-electrons.com>
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/reset/reset-simple.h>
+#include <linux/reset/sunxi.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+static int sunxi_reset_init(struct device_node *np)
+{
+	struct reset_simple_data *data;
+	struct resource res;
+	resource_size_t size;
+	int ret;
+
+	data = kzalloc_obj(*data);
+	if (!data)
+		return -ENOMEM;
+
+	ret = of_address_to_resource(np, 0, &res);
+	if (ret)
+		goto err_alloc;
+
+	size = resource_size(&res);
+	if (!request_mem_region(res.start, size, np->name)) {
+		ret = -EBUSY;
+		goto err_alloc;
+	}
+
+	data->membase = ioremap(res.start, size);
+	if (!data->membase) {
+		ret = -ENOMEM;
+		goto err_mem_region;
+	}
+
+	spin_lock_init(&data->lock);
+
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.nr_resets = size * 8;
+	data->rcdev.ops = &reset_simple_ops;
+	data->rcdev.of_node = np;
+	data->active_low = true;
+
+	return reset_controller_register(&data->rcdev);
+
+err_mem_region:
+	release_mem_region(res.start, size);
+err_alloc:
+	kfree(data);
+	return ret;
+};
+
+/*
+ * These are the reset controller we need to initialize early on in
+ * our system, before we can even think of using a regular device
+ * driver for it.
+ * The controllers that we can register through the regular device
+ * model are handled by the simple reset driver directly.
+ */
+static const struct of_device_id sunxi_early_reset_dt_ids[] __initconst = {
+	{ .compatible = "allwinner,sun6i-a31-ahb1-reset", },
+	{ /* sentinel */ },
+};
+
+void __init sun6i_reset_init(void)
+{
+	struct device_node *np;
+
+	for_each_matching_node(np, sunxi_early_reset_dt_ids)
+		sunxi_reset_init(np);
+}