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, 110 insertions, 0 deletions

diff --git a/drivers/clk/imx/clk-cpu.c b/drivers/clk/imx/clk-cpu.c
new file mode 100644
index 000000000..f53dbaacd
--- /dev/null
+++ b/drivers/clk/imx/clk-cpu.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2014 Lucas Stach <l.stach@pengutronix.de>, Pengutronix
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include "clk.h"
+
+struct clk_cpu {
+	struct clk_hw	hw;
+	struct clk	*div;
+	struct clk	*mux;
+	struct clk	*pll;
+	struct clk	*step;
+};
+
+static inline struct clk_cpu *to_clk_cpu(struct clk_hw *hw)
+{
+	return container_of(hw, struct clk_cpu, hw);
+}
+
+static unsigned long clk_cpu_recalc_rate(struct clk_hw *hw,
+					 unsigned long parent_rate)
+{
+	struct clk_cpu *cpu = to_clk_cpu(hw);
+
+	return clk_get_rate(cpu->div);
+}
+
+static int clk_cpu_determine_rate(struct clk_hw *hw,
+				  struct clk_rate_request *req)
+{
+	struct clk_cpu *cpu = to_clk_cpu(hw);
+
+	req->rate = clk_round_rate(cpu->pll, req->rate);
+
+	return 0;
+}
+
+static int clk_cpu_set_rate(struct clk_hw *hw, unsigned long rate,
+			    unsigned long parent_rate)
+{
+	struct clk_cpu *cpu = to_clk_cpu(hw);
+	int ret;
+
+	/* switch to PLL bypass clock */
+	ret = clk_set_parent(cpu->mux, cpu->step);
+	if (ret)
+		return ret;
+
+	/* reprogram PLL */
+	ret = clk_set_rate(cpu->pll, rate);
+	if (ret) {
+		clk_set_parent(cpu->mux, cpu->pll);
+		return ret;
+	}
+	/* switch back to PLL clock */
+	clk_set_parent(cpu->mux, cpu->pll);
+
+	/* Ensure the divider is what we expect */
+	clk_set_rate(cpu->div, rate);
+
+	return 0;
+}
+
+static const struct clk_ops clk_cpu_ops = {
+	.recalc_rate	= clk_cpu_recalc_rate,
+	.determine_rate = clk_cpu_determine_rate,
+	.set_rate	= clk_cpu_set_rate,
+};
+
+struct clk_hw *imx_clk_hw_cpu(const char *name, const char *parent_name,
+		struct clk *div, struct clk *mux, struct clk *pll,
+		struct clk *step)
+{
+	struct clk_cpu *cpu;
+	struct clk_hw *hw;
+	struct clk_init_data init;
+	int ret;
+
+	cpu = kzalloc_obj(*cpu);
+	if (!cpu)
+		return ERR_PTR(-ENOMEM);
+
+	cpu->div = div;
+	cpu->mux = mux;
+	cpu->pll = pll;
+	cpu->step = step;
+
+	init.name = name;
+	init.ops = &clk_cpu_ops;
+	init.flags = CLK_IS_CRITICAL;
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+
+	cpu->hw.init = &init;
+	hw = &cpu->hw;
+
+	ret = clk_hw_register(NULL, hw);
+	if (ret) {
+		kfree(cpu);
+		return ERR_PTR(ret);
+	}
+
+	return hw;
+}
+EXPORT_SYMBOL_GPL(imx_clk_hw_cpu);