Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 172 insertions, 0 deletions

diff --git a/include/media/media-devnode.h b/include/media/media-devnode.h
new file mode 100644
index 000000000..dbcabeffc
--- /dev/null
+++ b/include/media/media-devnode.h
@@ -0,0 +1,172 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Media device node
+ *
+ * Copyright (C) 2010 Nokia Corporation
+ *
+ * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+ *	     Sakari Ailus <sakari.ailus@iki.fi>
+ *
+ * --
+ *
+ * Common functions for media-related drivers to register and unregister media
+ * device nodes.
+ */
+
+#ifndef _MEDIA_DEVNODE_H
+#define _MEDIA_DEVNODE_H
+
+#include <linux/poll.h>
+#include <linux/fs.h>
+#include <linux/device.h>
+#include <linux/cdev.h>
+#include <linux/debugfs.h>
+
+struct media_device;
+
+/* debugfs top-level media directory */
+extern struct dentry *media_debugfs_root;
+
+/*
+ * Flag to mark the media_devnode struct as registered. Drivers must not touch
+ * this flag directly, it will be set and cleared by media_devnode_register and
+ * media_devnode_unregister.
+ */
+#define MEDIA_FLAG_REGISTERED	0
+
+/**
+ * struct media_file_operations - Media device file operations
+ *
+ * @owner: should be filled with %THIS_MODULE
+ * @read: pointer to the function that implements read() syscall
+ * @write: pointer to the function that implements write() syscall
+ * @poll: pointer to the function that implements poll() syscall
+ * @ioctl: pointer to the function that implements ioctl() syscall
+ * @compat_ioctl: pointer to the function that will handle 32 bits userspace
+ *	calls to the ioctl() syscall on a Kernel compiled with 64 bits.
+ * @open: pointer to the function that implements open() syscall
+ * @release: pointer to the function that will release the resources allocated
+ *	by the @open function.
+ */
+struct media_file_operations {
+	struct module *owner;
+	ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
+	ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
+	__poll_t (*poll) (struct file *, struct poll_table_struct *);
+	long (*ioctl) (struct file *, unsigned int, unsigned long);
+	long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
+	int (*open) (struct file *);
+	int (*release) (struct file *);
+};
+
+/**
+ * struct media_devnode - Media device node
+ * @media_dev:	pointer to struct &media_device
+ * @fops:	pointer to struct &media_file_operations with media device ops
+ * @dev:	pointer to struct &device containing the media controller device
+ * @cdev:	struct cdev pointer character device
+ * @parent:	parent device
+ * @minor:	device node minor number
+ * @flags:	flags, combination of the ``MEDIA_FLAG_*`` constants
+ * @release:	release callback called at the end of ``media_devnode_release()``
+ *		routine at media-device.c.
+ *
+ * This structure represents a media-related device node.
+ *
+ * The @parent is a physical device. It must be set by core or device drivers
+ * before registering the node.
+ */
+struct media_devnode {
+	struct media_device *media_dev;
+
+	/* device ops */
+	const struct media_file_operations *fops;
+
+	/* sysfs */
+	struct device dev;		/* media device */
+	struct cdev cdev;		/* character device */
+	struct device *parent;		/* device parent */
+
+	/* device info */
+	int minor;
+	unsigned long flags;		/* Use bitops to access flags */
+
+	/* callbacks */
+	void (*release)(struct media_devnode *devnode);
+};
+
+/* dev to media_devnode */
+#define to_media_devnode(cd) container_of(cd, struct media_devnode, dev)
+
+/**
+ * media_devnode_register - register a media device node
+ *
+ * @mdev: struct media_device we want to register a device node
+ * @devnode: media device node structure we want to register
+ * @owner: should be filled with %THIS_MODULE
+ *
+ * The registration code assigns minor numbers and registers the new device node
+ * with the kernel. An error is returned if no free minor number can be found,
+ * or if the registration of the device node fails.
+ *
+ * Zero is returned on success.
+ *
+ * Note that if the media_devnode_register call fails, the release() callback of
+ * the media_devnode structure is *not* called, so the caller is responsible for
+ * freeing any data.
+ */
+int __must_check media_devnode_register(struct media_device *mdev,
+					struct media_devnode *devnode,
+					struct module *owner);
+
+/**
+ * media_devnode_unregister_prepare - clear the media device node register bit
+ * @devnode: the device node to prepare for unregister
+ *
+ * This clears the passed device register bit. Future open calls will be met
+ * with errors. Should be called before media_devnode_unregister() to avoid
+ * races with unregister and device file open calls.
+ *
+ * This function can safely be called if the device node has never been
+ * registered or has already been unregistered.
+ */
+void media_devnode_unregister_prepare(struct media_devnode *devnode);
+
+/**
+ * media_devnode_unregister - unregister a media device node
+ * @devnode: the device node to unregister
+ *
+ * This unregisters the passed device. Future open calls will be met with
+ * errors.
+ *
+ * Should be called after media_devnode_unregister_prepare()
+ */
+void media_devnode_unregister(struct media_devnode *devnode);
+
+/**
+ * media_devnode_data - returns a pointer to the &media_devnode
+ *
+ * @filp: pointer to struct &file
+ */
+static inline struct media_devnode *media_devnode_data(struct file *filp)
+{
+	return filp->private_data;
+}
+
+/**
+ * media_devnode_is_registered - returns true if &media_devnode is registered;
+ *	false otherwise.
+ *
+ * @devnode: pointer to struct &media_devnode.
+ *
+ * Note: If mdev is NULL, it also returns false.
+ */
+static inline int media_devnode_is_registered(struct media_devnode *devnode)
+{
+	if (!devnode)
+		return false;
+
+	return test_bit(MEDIA_FLAG_REGISTERED, &devnode->flags);
+}
+
+#endif /* _MEDIA_DEVNODE_H */