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, 52 insertions, 0 deletions

diff --git a/tools/perf/util/dsos.h b/tools/perf/util/dsos.h
new file mode 100644
index 000000000..a26774950
--- /dev/null
+++ b/tools/perf/util/dsos.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_DSOS
+#define __PERF_DSOS
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <linux/list.h>
+#include <linux/rbtree.h>
+#include "rwsem.h"
+
+struct dso;
+struct dso_id;
+struct kmod_path;
+struct machine;
+
+/*
+ * Collection of DSOs as an array for iteration speed, but sorted for O(n)
+ * lookup.
+ */
+struct dsos {
+	struct rw_semaphore lock;
+	struct dso **dsos;
+	unsigned int cnt;
+	unsigned int allocated;
+	bool sorted;
+};
+
+void dsos__init(struct dsos *dsos);
+void dsos__exit(struct dsos *dsos);
+
+int __dsos__add(struct dsos *dsos, struct dso *dso);
+int dsos__add(struct dsos *dsos, struct dso *dso);
+struct dso *dsos__find(struct dsos *dsos, const char *name, bool cmp_short);
+
+struct dso *dsos__findnew_id(struct dsos *dsos, const char *name, const struct dso_id *id);
+ 
+bool dsos__read_build_ids(struct dsos *dsos, bool with_hits);
+
+size_t dsos__fprintf_buildid(struct dsos *dsos, FILE *fp,
+			       bool (skip)(struct dso *dso, int parm), int parm);
+size_t dsos__fprintf(struct dsos *dsos, FILE *fp);
+
+int dsos__hit_all(struct dsos *dsos);
+
+struct dso *dsos__findnew_module_dso(struct dsos *dsos, struct machine *machine,
+				     struct kmod_path *m, const char *filename);
+
+struct dso *dsos__find_kernel_dso(struct dsos *dsos);
+
+int dsos__for_each_dso(struct dsos *dsos, int (*cb)(struct dso *dso, void *data), void *data);
+
+#endif /* __PERF_DSOS */