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, 33 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/wl.h b/drivers/mtd/ubi/wl.h
new file mode 100644
index 000000000..a69169c35
--- /dev/null
+++ b/drivers/mtd/ubi/wl.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef UBI_WL_H
+#define UBI_WL_H
+#ifdef CONFIG_MTD_UBI_FASTMAP
+static void update_fastmap_work_fn(struct work_struct *wrk);
+static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root);
+static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi);
+static struct ubi_wl_entry *next_peb_for_wl(struct ubi_device *ubi,
+					    bool need_fill);
+static bool need_wear_leveling(struct ubi_device *ubi);
+static void ubi_fastmap_close(struct ubi_device *ubi);
+static inline void ubi_fastmap_init(struct ubi_device *ubi, int *count)
+{
+	if (ubi->fm_disabled)
+		ubi->fm_pool_rsv_cnt = 0;
+	/* Reserve enough LEBs to store two fastmaps and to fill pools. */
+	*count += (ubi->fm_size / ubi->leb_size) * 2 + ubi->fm_pool_rsv_cnt;
+	INIT_WORK(&ubi->fm_work, update_fastmap_work_fn);
+}
+static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi,
+					       struct ubi_wl_entry *e,
+					       struct rb_root *root);
+#else /* !CONFIG_MTD_UBI_FASTMAP */
+static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi);
+static inline void ubi_fastmap_close(struct ubi_device *ubi) { }
+static inline void ubi_fastmap_init(struct ubi_device *ubi, int *count) { }
+static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi,
+					       struct ubi_wl_entry *e,
+					       struct rb_root *root) {
+	return e;
+}
+#endif /* CONFIG_MTD_UBI_FASTMAP */
+#endif /* UBI_WL_H */