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, 34 insertions, 0 deletions

diff --git a/drivers/gpib/common/ibsys.h b/drivers/gpib/common/ibsys.h
new file mode 100644
index 000000000..e5a148f51
--- /dev/null
+++ b/drivers/gpib/common/ibsys.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include "gpibP.h"
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/major.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/timer.h>
+
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <asm/irq.h>
+#include <asm/dma.h>
+
+#define MAX_GPIB_PRIMARY_ADDRESS 30
+#define MAX_GPIB_SECONDARY_ADDRESS 31
+
+int gpib_allocate_board(struct gpib_board *board);
+void gpib_deallocate_board(struct gpib_board *board);
+
+unsigned int num_status_bytes(const struct gpib_status_queue *dev);
+int push_status_byte(struct gpib_board *board, struct gpib_status_queue *device,
+		     u8 poll_byte);
+int pop_status_byte(struct gpib_board *board, struct gpib_status_queue *device,
+		    u8 *poll_byte);
+struct gpib_status_queue *get_gpib_status_queue(struct gpib_board *board,
+						unsigned int pad, int sad);
+int get_serial_poll_byte(struct gpib_board *board, unsigned int pad, int sad,
+			 unsigned int usec_timeout, u8 *poll_byte);
+int autopoll_all_devices(struct gpib_board *board);