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, 54 insertions, 0 deletions

diff --git a/include/net/netprio_cgroup.h b/include/net/netprio_cgroup.h
new file mode 100644
index 000000000..dec7522b6
--- /dev/null
+++ b/include/net/netprio_cgroup.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * netprio_cgroup.h			Control Group Priority set
+ *
+ * Authors:	Neil Horman <nhorman@tuxdriver.com>
+ */
+
+#ifndef _NETPRIO_CGROUP_H
+#define _NETPRIO_CGROUP_H
+
+#include <linux/cgroup.h>
+#include <linux/hardirq.h>
+#include <linux/rcupdate.h>
+
+#if IS_ENABLED(CONFIG_CGROUP_NET_PRIO)
+struct netprio_map {
+	struct rcu_head rcu;
+	u32 priomap_len;
+	u32 priomap[];
+};
+
+static inline u32 task_netprioidx(struct task_struct *p)
+{
+	struct cgroup_subsys_state *css;
+	u32 idx;
+
+	rcu_read_lock();
+	css = task_css(p, net_prio_cgrp_id);
+	idx = css->id;
+	rcu_read_unlock();
+	return idx;
+}
+
+static inline void sock_update_netprioidx(struct sock_cgroup_data *skcd)
+{
+	if (in_interrupt())
+		return;
+
+	sock_cgroup_set_prioidx(skcd, task_netprioidx(current));
+}
+
+#else /* !CONFIG_CGROUP_NET_PRIO */
+
+static inline u32 task_netprioidx(struct task_struct *p)
+{
+	return 0;
+}
+
+static inline void sock_update_netprioidx(struct sock_cgroup_data *skcd)
+{
+}
+
+#endif /* CONFIG_CGROUP_NET_PRIO */
+#endif  /* _NET_CLS_CGROUP_H */