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, 281 insertions, 0 deletions

diff --git a/include/media/dvb_vb2.h b/include/media/dvb_vb2.h
new file mode 100644
index 000000000..8932396d2
--- /dev/null
+++ b/include/media/dvb_vb2.h
@@ -0,0 +1,281 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0
+ *
+ * dvb-vb2.h - DVB driver helper framework for streaming I/O
+ *
+ * Copyright (C) 2015 Samsung Electronics
+ *
+ * Author: jh1009.sung@samsung.com
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation.
+ */
+
+#ifndef _DVB_VB2_H
+#define _DVB_VB2_H
+
+#include <linux/mutex.h>
+#include <linux/poll.h>
+#include <linux/dvb/dmx.h>
+#include <media/videobuf2-core.h>
+#include <media/videobuf2-dma-contig.h>
+#include <media/videobuf2-vmalloc.h>
+
+/**
+ * enum dvb_buf_type - types of Digital TV memory-mapped buffers
+ *
+ * @DVB_BUF_TYPE_CAPTURE: buffer is filled by the Kernel,
+ *			  with a received Digital TV stream
+ */
+enum dvb_buf_type {
+	DVB_BUF_TYPE_CAPTURE        = 1,
+};
+
+/**
+ * enum dvb_vb2_states - states to control VB2 state machine
+ * @DVB_VB2_STATE_NONE:
+ *	VB2 engine not initialized yet, init failed or VB2 was released.
+ * @DVB_VB2_STATE_INIT:
+ *	VB2 engine initialized.
+ * @DVB_VB2_STATE_REQBUFS:
+ *	Buffers were requested
+ * @DVB_VB2_STATE_STREAMON:
+ *	VB2 is streaming. Callers should not check it directly. Instead,
+ *	they should use dvb_vb2_is_streaming().
+ *
+ * Note:
+ *
+ * Callers should not touch at the state machine directly. This
+ * is handled inside dvb_vb2.c.
+ */
+enum dvb_vb2_states {
+	DVB_VB2_STATE_NONE	= 0x0,
+	DVB_VB2_STATE_INIT	= 0x1,
+	DVB_VB2_STATE_REQBUFS	= 0x2,
+	DVB_VB2_STATE_STREAMON	= 0x4,
+};
+
+#define DVB_VB2_NAME_MAX (20)
+
+/**
+ * struct dvb_buffer - video buffer information for v4l2.
+ *
+ * @vb:		embedded struct &vb2_buffer.
+ * @list:	list of &struct dvb_buffer.
+ */
+struct dvb_buffer {
+	struct vb2_buffer	vb;
+	struct list_head	list;
+};
+
+/**
+ * struct dvb_vb2_ctx - control struct for VB2 handler
+ * @vb_q:	pointer to &struct vb2_queue with videobuf2 queue.
+ * @slock:	spin lock used to protect buffer filling at dvb_vb2.c.
+ * @dvb_q:	List of buffers that are not filled yet.
+ * @buf:	Pointer to the buffer that are currently being filled.
+ * @offset:	index to the next position at the @buf to be filled.
+ * @remain:	How many bytes are left to be filled at @buf.
+ * @state:	bitmask of buffer states as defined by &enum dvb_vb2_states.
+ * @buf_siz:	size of each VB2 buffer.
+ * @buf_cnt:	number of VB2 buffers.
+ * @nonblocking:
+ *		If different than zero, device is operating on non-blocking
+ *		mode.
+ * @flags:	buffer flags as defined by &enum dmx_buffer_flags.
+ *		Filled only at &DMX_DQBUF. &DMX_QBUF should zero this field.
+ * @count:	monotonic counter for filled buffers. Helps to identify
+ *		data stream loses. Filled only at &DMX_DQBUF. &DMX_QBUF should
+ *		zero this field.
+ *
+ * @name:	name of the device type. Currently, it can either be
+ *		"dvr" or "demux_filter".
+ */
+struct dvb_vb2_ctx {
+	struct vb2_queue	vb_q;
+	spinlock_t		slock;
+	struct list_head	dvb_q;
+	struct dvb_buffer	*buf;
+	int	offset;
+	int	remain;
+	int	state;
+	int	buf_siz;
+	int	buf_cnt;
+	int	nonblocking;
+
+	enum dmx_buffer_flags flags;
+	u32	count;
+
+	char	name[DVB_VB2_NAME_MAX + 1];
+};
+
+#ifndef CONFIG_DVB_MMAP
+static inline int dvb_vb2_init(struct dvb_vb2_ctx *ctx, const char *name,
+			       struct mutex *mutex, int non_blocking)
+{
+	return 0;
+};
+static inline int dvb_vb2_release(struct dvb_vb2_ctx *ctx)
+{
+	return 0;
+};
+#define dvb_vb2_is_streaming(ctx) (0)
+#define dvb_vb2_fill_buffer(ctx, file, wait, flags, flush) (0)
+
+static inline __poll_t dvb_vb2_poll(struct dvb_vb2_ctx *ctx,
+				    struct file *file,
+				    poll_table *wait)
+{
+	return 0;
+}
+#else
+/**
+ * dvb_vb2_init - initializes VB2 handler
+ *
+ * @ctx:	control struct for VB2 handler
+ * @name:	name for the VB2 handler
+ * @mutex:	pointer to the mutex that serializes vb2 ioctls
+ * @non_blocking:
+ *		if not zero, it means that the device is at non-blocking mode
+ */
+int dvb_vb2_init(struct dvb_vb2_ctx *ctx, const char *name,
+		 struct mutex *mutex, int non_blocking);
+
+/**
+ * dvb_vb2_release - Releases the VB2 handler allocated resources and
+ *	put @ctx at DVB_VB2_STATE_NONE state.
+ * @ctx:	control struct for VB2 handler
+ */
+int dvb_vb2_release(struct dvb_vb2_ctx *ctx);
+
+/**
+ * dvb_vb2_is_streaming - checks if the VB2 handler is streaming
+ * @ctx:	control struct for VB2 handler
+ *
+ * Return: 0 if not streaming, 1 otherwise.
+ */
+int dvb_vb2_is_streaming(struct dvb_vb2_ctx *ctx);
+
+/**
+ * dvb_vb2_fill_buffer - fills a VB2 buffer
+ * @ctx:	control struct for VB2 handler
+ * @src:	place where the data is stored
+ * @len:	number of bytes to be copied from @src
+ * @buffer_flags:
+ *		pointer to buffer flags as defined by &enum dmx_buffer_flags.
+ *		can be NULL.
+ * @flush:	flush the buffer, even if it isn't full.
+ */
+int dvb_vb2_fill_buffer(struct dvb_vb2_ctx *ctx,
+			const unsigned char *src, int len,
+			enum dmx_buffer_flags *buffer_flags,
+			bool flush);
+
+/**
+ * dvb_vb2_poll - Wrapper to vb2_core_streamon() for Digital TV
+ *      buffer handling.
+ *
+ * @ctx:	control struct for VB2 handler
+ * @file:	&struct file argument passed to the poll
+ *		file operation handler.
+ * @wait:	&poll_table wait argument passed to the poll
+ *		file operation handler.
+ *
+ * Implements poll syscall() logic.
+ */
+__poll_t dvb_vb2_poll(struct dvb_vb2_ctx *ctx, struct file *file,
+		      poll_table *wait);
+#endif
+
+/**
+ * dvb_vb2_stream_on() - Wrapper to vb2_core_streamon() for Digital TV
+ *	buffer handling.
+ *
+ * @ctx:	control struct for VB2 handler
+ *
+ * Starts dvb streaming
+ */
+int dvb_vb2_stream_on(struct dvb_vb2_ctx *ctx);
+/**
+ * dvb_vb2_stream_off() - Wrapper to vb2_core_streamoff() for Digital TV
+ *	buffer handling.
+ *
+ * @ctx:	control struct for VB2 handler
+ *
+ * Stops dvb streaming
+ */
+int dvb_vb2_stream_off(struct dvb_vb2_ctx *ctx);
+
+/**
+ * dvb_vb2_reqbufs() - Wrapper to vb2_core_reqbufs() for Digital TV
+ *	buffer handling.
+ *
+ * @ctx:	control struct for VB2 handler
+ * @req:	&struct dmx_requestbuffers passed from userspace in
+ *		order to handle &DMX_REQBUFS.
+ *
+ * Initiate streaming by requesting a number of buffers. Also used to
+ * free previously requested buffers, is ``req->count`` is zero.
+ */
+int dvb_vb2_reqbufs(struct dvb_vb2_ctx *ctx, struct dmx_requestbuffers *req);
+
+/**
+ * dvb_vb2_querybuf() - Wrapper to vb2_core_querybuf() for Digital TV
+ *	buffer handling.
+ *
+ * @ctx:	control struct for VB2 handler
+ * @b:		&struct dmx_buffer passed from userspace in
+ *		order to handle &DMX_QUERYBUF.
+ *
+ *
+ */
+int dvb_vb2_querybuf(struct dvb_vb2_ctx *ctx, struct dmx_buffer *b);
+
+/**
+ * dvb_vb2_expbuf() - Wrapper to vb2_core_expbuf() for Digital TV
+ *	buffer handling.
+ *
+ * @ctx:	control struct for VB2 handler
+ * @exp:	&struct dmx_exportbuffer passed from userspace in
+ *		order to handle &DMX_EXPBUF.
+ *
+ * Export a buffer as a file descriptor.
+ */
+int dvb_vb2_expbuf(struct dvb_vb2_ctx *ctx, struct dmx_exportbuffer *exp);
+
+/**
+ * dvb_vb2_qbuf() - Wrapper to vb2_core_qbuf() for Digital TV buffer handling.
+ *
+ * @ctx:	control struct for VB2 handler
+ * @b:		&struct dmx_buffer passed from userspace in
+ *		order to handle &DMX_QBUF.
+ *
+ * Queue a Digital TV buffer as requested by userspace
+ */
+int dvb_vb2_qbuf(struct dvb_vb2_ctx *ctx, struct dmx_buffer *b);
+
+/**
+ * dvb_vb2_dqbuf() - Wrapper to vb2_core_dqbuf() for Digital TV
+ *	buffer handling.
+ *
+ * @ctx:	control struct for VB2 handler
+ * @b:		&struct dmx_buffer passed from userspace in
+ *		order to handle &DMX_DQBUF.
+ *
+ * Dequeue a Digital TV buffer to the userspace
+ */
+int dvb_vb2_dqbuf(struct dvb_vb2_ctx *ctx, struct dmx_buffer *b);
+
+/**
+ * dvb_vb2_mmap() - Wrapper to vb2_mmap() for Digital TV buffer handling.
+ *
+ * @ctx:	control struct for VB2 handler
+ * @vma:        pointer to &struct vm_area_struct with the vma passed
+ *              to the mmap file operation handler in the driver.
+ *
+ * map Digital TV video buffers into application address space.
+ */
+int dvb_vb2_mmap(struct dvb_vb2_ctx *ctx, struct vm_area_struct *vma);
+
+#endif /* _DVB_VB2_H */