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, 98 insertions, 0 deletions

diff --git a/tools/perf/util/target.h b/tools/perf/util/target.h
new file mode 100644
index 000000000..bc2bff9c6
--- /dev/null
+++ b/tools/perf/util/target.h
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PERF_TARGET_H
+#define _PERF_TARGET_H
+
+#include <stdbool.h>
+#include <sys/types.h>
+
+struct target {
+	const char   *pid;
+	const char   *tid;
+	const char   *cpu_list;
+	const char   *bpf_str;
+	bool	     system_wide;
+	bool	     uses_mmap;
+	bool	     default_per_cpu;
+	bool	     per_thread;
+	bool	     use_bpf;
+	bool	     inherit;
+	int	     initial_delay;
+	const char   *attr_map;
+};
+
+enum target_errno {
+	TARGET_ERRNO__SUCCESS		= 0,
+
+	/*
+	 * Choose an arbitrary negative big number not to clash with standard
+	 * errno since SUS requires the errno has distinct positive values.
+	 * See 'Issue 6' in the link below.
+	 *
+	 * http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/errno.h.html
+	 */
+	__TARGET_ERRNO__START		= -10000,
+
+	/* for target__validate() */
+	TARGET_ERRNO__PID_OVERRIDE_CPU	= __TARGET_ERRNO__START,
+	TARGET_ERRNO__PID_OVERRIDE_SYSTEM,
+	TARGET_ERRNO__SYSTEM_OVERRIDE_THREAD,
+	TARGET_ERRNO__BPF_OVERRIDE_CPU,
+	TARGET_ERRNO__BPF_OVERRIDE_PID,
+	TARGET_ERRNO__BPF_OVERRIDE_THREAD,
+
+	__TARGET_ERRNO__END,
+};
+
+enum target_errno target__validate(struct target *target);
+
+uid_t parse_uid(const char *str);
+
+int target__strerror(struct target *target, int errnum, char *buf, size_t buflen);
+
+static inline bool target__has_task(const struct target *target)
+{
+	return target->tid || target->pid;
+}
+
+static inline bool target__has_cpu(const struct target *target)
+{
+	return target->system_wide || target->cpu_list;
+}
+
+static inline bool target__none(const struct target *target)
+{
+	return !target__has_task(target) && !target__has_cpu(target);
+}
+
+static inline bool target__enable_on_exec(const struct target *target)
+{
+	/*
+	 * Normally enable_on_exec should be set if:
+	 *  1) The tracee process is forked (not attaching to existed task or cpu).
+	 *  2) And initial_delay is not configured.
+	 * Otherwise, we enable tracee events manually.
+	 */
+	return target__none(target) && !target->initial_delay;
+}
+
+static inline bool target__has_per_thread(const struct target *target)
+{
+	return target->system_wide && target->per_thread;
+}
+
+static inline bool target__uses_dummy_map(const struct target *target)
+{
+	bool use_dummy = false;
+
+	if (target->default_per_cpu)
+		use_dummy = target->per_thread ? true : false;
+	else if (target__has_task(target) ||
+	         (!target__has_cpu(target) && !target->uses_mmap))
+		use_dummy = true;
+	else if (target__has_per_thread(target))
+		use_dummy = true;
+
+	return use_dummy;
+}
+
+#endif /* _PERF_TARGET_H */