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, 82 insertions, 0 deletions

diff --git a/tools/perf/util/probe-file.h b/tools/perf/util/probe-file.h
new file mode 100644
index 000000000..c2bb6a5b9
--- /dev/null
+++ b/tools/perf/util/probe-file.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PROBE_FILE_H
+#define __PROBE_FILE_H
+
+#include "probe-event.h"
+
+struct strlist;
+struct strfilter;
+
+/* Cache of probe definitions */
+struct probe_cache_entry {
+	struct list_head	node;
+	bool			sdt;
+	struct perf_probe_event pev;
+	char			*spev;
+	struct strlist		*tevlist;
+};
+
+struct probe_cache {
+	int	fd;
+	struct list_head entries;
+};
+
+enum probe_type {
+	PROBE_TYPE_U = 0,
+	PROBE_TYPE_S,
+	PROBE_TYPE_X,
+	PROBE_TYPE_STRING,
+	PROBE_TYPE_BITFIELD,
+	PROBE_TYPE_END,
+};
+
+#define PF_FL_UPROBE	1
+#define PF_FL_RW	2
+#define for_each_probe_cache_entry(entry, pcache) \
+	list_for_each_entry(entry, &pcache->entries, node)
+
+/* probe-file.c depends on libelf */
+#ifdef HAVE_LIBELF_SUPPORT
+int open_trace_file(const char *trace_file, bool readwrite);
+int probe_file__open(int flag);
+int probe_file__open_both(int *kfd, int *ufd, int flag);
+struct strlist *probe_file__get_namelist(int fd);
+struct strlist *probe_file__get_rawlist(int fd);
+int probe_file__add_event(int fd, struct probe_trace_event *tev);
+
+int probe_file__get_events(int fd, struct strfilter *filter,
+				  struct strlist *plist);
+int probe_file__del_strlist(int fd, struct strlist *namelist);
+
+int probe_cache_entry__get_event(struct probe_cache_entry *entry,
+				 struct probe_trace_event **tevs);
+
+struct probe_cache *probe_cache__new(const char *target, struct nsinfo *nsi);
+int probe_cache__add_entry(struct probe_cache *pcache,
+			   struct perf_probe_event *pev,
+			   struct probe_trace_event *tevs, int ntevs);
+int probe_cache__scan_sdt(struct probe_cache *pcache, const char *pathname);
+int probe_cache__commit(struct probe_cache *pcache);
+void probe_cache__purge(struct probe_cache *pcache);
+void probe_cache__delete(struct probe_cache *pcache);
+int probe_cache__filter_purge(struct probe_cache *pcache,
+			      struct strfilter *filter);
+struct probe_cache_entry *probe_cache__find(struct probe_cache *pcache,
+					    struct perf_probe_event *pev);
+struct probe_cache_entry *probe_cache__find_by_name(struct probe_cache *pcache,
+					const char *group, const char *event);
+int probe_cache__show_all_caches(struct strfilter *filter);
+bool probe_type_is_available(enum probe_type type);
+bool kretprobe_offset_is_supported(void);
+bool uprobe_ref_ctr_is_supported(void);
+bool user_access_is_supported(void);
+bool multiprobe_event_is_supported(void);
+bool immediate_value_is_supported(void);
+#else	/* ! HAVE_LIBELF_SUPPORT */
+static inline struct probe_cache *probe_cache__new(const char *tgt __maybe_unused, struct nsinfo *nsi __maybe_unused)
+{
+	return NULL;
+}
+#define probe_cache__delete(pcache) do {} while (0)
+#endif
+#endif