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, 64 insertions, 0 deletions

diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
new file mode 100644
index 000000000..4d72c5fa5
--- /dev/null
+++ b/tools/perf/util/mmap.h
@@ -0,0 +1,64 @@
+#ifndef __PERF_MMAP_H
+#define __PERF_MMAP_H 1
+
+#include <internal/mmap.h>
+#include <linux/types.h>
+#include <linux/bitops.h>
+#include <perf/cpumap.h>
+#ifdef HAVE_AIO_SUPPORT
+#include <aio.h>
+#endif
+#include "auxtrace.h"
+#include "util/compress.h"
+
+struct aiocb;
+
+struct mmap_cpu_mask {
+	unsigned long *bits;
+	size_t nbits;
+};
+
+#define MMAP_CPU_MASK_BYTES(m) \
+	(BITS_TO_LONGS(((struct mmap_cpu_mask *)m)->nbits) * sizeof(unsigned long))
+
+/**
+ * struct mmap - perf's ring buffer mmap details
+ *
+ * @refcnt - e.g. code using PERF_EVENT_IOC_SET_OUTPUT to share this
+ */
+struct mmap {
+	struct perf_mmap	core;
+	struct auxtrace_mmap auxtrace_mmap;
+#ifdef HAVE_AIO_SUPPORT
+	struct {
+		void		 **data;
+		struct aiocb	 *cblocks;
+		struct aiocb	 **aiocb;
+		int		 nr_cblocks;
+	} aio;
+#endif
+	struct mmap_cpu_mask	affinity_mask;
+	void		*data;
+	struct perf_data_file *file;
+	struct zstd_data      zstd_data;
+};
+
+struct mmap_params {
+	struct perf_mmap_param core;
+	int nr_cblocks, affinity, flush, comp_level;
+	struct auxtrace_mmap_params auxtrace_mp;
+};
+
+int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, struct perf_cpu cpu);
+void mmap__munmap(struct mmap *map);
+
+union perf_event *perf_mmap__read_forward(struct mmap *map);
+
+int perf_mmap__push(struct mmap *md, void *to,
+		    int push(struct mmap *map, void *to, void *buf, size_t size));
+
+size_t mmap__mmap_len(struct mmap *map);
+
+void mmap_cpu_mask__scnprintf(struct mmap_cpu_mask *mask, const char *tag);
+
+#endif /*__PERF_MMAP_H */