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, 39 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq_powersave.c b/drivers/cpufreq/cpufreq_powersave.c
new file mode 100644
index 000000000..8d830d860
--- /dev/null
+++ b/drivers/cpufreq/cpufreq_powersave.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/drivers/cpufreq/cpufreq_powersave.c
+ *
+ * Copyright (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cpufreq.h>
+#include <linux/init.h>
+#include <linux/module.h>
+
+static void cpufreq_gov_powersave_limits(struct cpufreq_policy *policy)
+{
+	pr_debug("setting to %u kHz\n", policy->min);
+	__cpufreq_driver_target(policy, policy->min, CPUFREQ_RELATION_L);
+}
+
+static struct cpufreq_governor cpufreq_gov_powersave = {
+	.name		= "powersave",
+	.limits		= cpufreq_gov_powersave_limits,
+	.owner		= THIS_MODULE,
+	.flags		= CPUFREQ_GOV_STRICT_TARGET,
+};
+
+MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
+MODULE_DESCRIPTION("CPUfreq policy governor 'powersave'");
+MODULE_LICENSE("GPL");
+
+#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_POWERSAVE
+struct cpufreq_governor *cpufreq_default_governor(void)
+{
+	return &cpufreq_gov_powersave;
+}
+#endif
+
+cpufreq_governor_init(cpufreq_gov_powersave);
+cpufreq_governor_exit(cpufreq_gov_powersave);