ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 78 insertions, 0 deletions

diff --git a/tools/perf/util/cputopo.h b/tools/perf/util/cputopo.h
new file mode 100644
index 000000000..8d42f6102
--- /dev/null
+++ b/tools/perf/util/cputopo.h
@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_CPUTOPO_H
+#define __PERF_CPUTOPO_H
+
+#include <linux/types.h>
+
+struct cpu_topology {
+	/* The number of unique package_cpus_lists below. */
+	u32	  package_cpus_lists;
+	/* The number of unique die_cpu_lists below. */
+	u32	  die_cpus_lists;
+	/* The number of unique core_cpu_lists below. */
+	u32	  core_cpus_lists;
+	/*
+	 * An array of strings where each string is unique and read from
+	 * /sys/devices/system/cpu/cpuX/topology/package_cpus_list. From the ABI
+	 * each of these is a human-readable list of CPUs sharing the same
+	 * physical_package_id. The format is like 0-3, 8-11, 14,17.
+	 */
+	const char **package_cpus_list;
+	/*
+	 * An array of string where each string is unique and from
+	 * /sys/devices/system/cpu/cpuX/topology/die_cpus_list. From the ABI
+	 * each of these is a human-readable list of CPUs within the same die.
+	 * The format is like 0-3, 8-11, 14,17.
+	 */
+	const char **die_cpus_list;
+	/*
+	 * An array of string where each string is unique and from
+	 * /sys/devices/system/cpu/cpuX/topology/core_cpus_list. From the ABI
+	 * each of these is a human-readable list of CPUs within the same
+	 * core. The format is like 0-3, 8-11, 14,17.
+	 */
+	const char **core_cpus_list;
+};
+
+struct numa_topology_node {
+	char		*cpus;
+	u32		 node;
+	u64		 mem_total;
+	u64		 mem_free;
+};
+
+struct numa_topology {
+	u32				nr;
+	struct numa_topology_node	nodes[];
+};
+
+struct hybrid_topology_node {
+	char		*pmu_name;
+	char		*cpus;
+};
+
+struct hybrid_topology {
+	u32				nr;
+	struct hybrid_topology_node	nodes[];
+};
+
+/*
+ * The topology for online CPUs, lazily created.
+ */
+const struct cpu_topology *online_topology(void);
+
+struct cpu_topology *cpu_topology__new(void);
+void cpu_topology__delete(struct cpu_topology *tp);
+/* Determine from the core list whether SMT was enabled. */
+bool cpu_topology__smt_on(const struct cpu_topology *topology);
+/* Are the sets of SMT siblings all enabled or all disabled in user_requested_cpus. */
+bool cpu_topology__core_wide(const struct cpu_topology *topology,
+			     const char *user_requested_cpu_list);
+
+struct numa_topology *numa_topology__new(void);
+void numa_topology__delete(struct numa_topology *tp);
+
+struct hybrid_topology *hybrid_topology__new(void);
+void hybrid_topology__delete(struct hybrid_topology *tp);
+
+#endif /* __PERF_CPUTOPO_H */