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, 245 insertions, 0 deletions

diff --git a/Documentation/input/uinput.rst b/Documentation/input/uinput.rst
new file mode 100644
index 000000000..30fe80e32
--- /dev/null
+++ b/Documentation/input/uinput.rst
@@ -0,0 +1,245 @@
+=============
+uinput module
+=============
+
+Introduction
+============
+
+uinput is a kernel module that makes it possible to emulate input devices
+from userspace. By writing to /dev/uinput (or /dev/input/uinput) device, a
+process can create a virtual input device with specific capabilities. Once
+this virtual device is created, the process can send events through it,
+that will be delivered to userspace and in-kernel consumers.
+
+Interface
+=========
+
+::
+
+  linux/uinput.h
+
+The uinput header defines ioctls to create, set up, and destroy virtual
+devices.
+
+libevdev
+========
+
+libevdev is a wrapper library for evdev devices that provides interfaces to
+create uinput devices and send events. libevdev is less error-prone than
+accessing uinput directly, and should be considered for new software.
+
+For examples and more information about libevdev:
+https://www.freedesktop.org/software/libevdev/doc/latest/
+
+Examples
+========
+
+Keyboard events
+---------------
+
+This first example shows how to create a new virtual device, and how to
+send a key event. All default imports and error handlers were removed for
+the sake of simplicity.
+
+.. code-block:: c
+
+   #include <linux/uinput.h>
+
+   void emit(int fd, int type, int code, int val)
+   {
+      struct input_event ie;
+
+      ie.type = type;
+      ie.code = code;
+      ie.value = val;
+      /* timestamp values below are ignored */
+      ie.time.tv_sec = 0;
+      ie.time.tv_usec = 0;
+
+      write(fd, &ie, sizeof(ie));
+   }
+
+   int main(void)
+   {
+      struct uinput_setup usetup;
+
+      int fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
+
+
+      /*
+       * The ioctls below will enable the device that is about to be
+       * created, to pass key events, in this case the space key.
+       */
+      ioctl(fd, UI_SET_EVBIT, EV_KEY);
+      ioctl(fd, UI_SET_KEYBIT, KEY_SPACE);
+
+      memset(&usetup, 0, sizeof(usetup));
+      usetup.id.bustype = BUS_USB;
+      usetup.id.vendor = 0x1234; /* sample vendor */
+      usetup.id.product = 0x5678; /* sample product */
+      strcpy(usetup.name, "Example device");
+
+      ioctl(fd, UI_DEV_SETUP, &usetup);
+      ioctl(fd, UI_DEV_CREATE);
+
+      /*
+       * On UI_DEV_CREATE the kernel will create the device node for this
+       * device. We are inserting a pause here so that userspace has time
+       * to detect, initialize the new device, and can start listening to
+       * the event, otherwise it will not notice the event we are about
+       * to send. This pause is only needed in our example code!
+       */
+      sleep(1);
+
+      /* Key press, report the event, send key release, and report again */
+      emit(fd, EV_KEY, KEY_SPACE, 1);
+      emit(fd, EV_SYN, SYN_REPORT, 0);
+      emit(fd, EV_KEY, KEY_SPACE, 0);
+      emit(fd, EV_SYN, SYN_REPORT, 0);
+
+      /*
+       * Give userspace some time to read the events before we destroy the
+       * device with UI_DEV_DESTROY.
+       */
+      sleep(1);
+
+      ioctl(fd, UI_DEV_DESTROY);
+      close(fd);
+
+      return 0;
+   }
+
+Mouse movements
+---------------
+
+This example shows how to create a virtual device that behaves like a physical
+mouse.
+
+.. code-block:: c
+
+   #include <linux/uinput.h>
+
+   /* emit function is identical to of the first example */
+
+   int main(void)
+   {
+      struct uinput_setup usetup;
+      int i = 50;
+
+      int fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
+
+      /* enable mouse button left and relative events */
+      ioctl(fd, UI_SET_EVBIT, EV_KEY);
+      ioctl(fd, UI_SET_KEYBIT, BTN_LEFT);
+
+      ioctl(fd, UI_SET_EVBIT, EV_REL);
+      ioctl(fd, UI_SET_RELBIT, REL_X);
+      ioctl(fd, UI_SET_RELBIT, REL_Y);
+
+      memset(&usetup, 0, sizeof(usetup));
+      usetup.id.bustype = BUS_USB;
+      usetup.id.vendor = 0x1234; /* sample vendor */
+      usetup.id.product = 0x5678; /* sample product */
+      strcpy(usetup.name, "Example device");
+
+      ioctl(fd, UI_DEV_SETUP, &usetup);
+      ioctl(fd, UI_DEV_CREATE);
+
+      /*
+       * On UI_DEV_CREATE the kernel will create the device node for this
+       * device. We are inserting a pause here so that userspace has time
+       * to detect, initialize the new device, and can start listening to
+       * the event, otherwise it will not notice the event we are about
+       * to send. This pause is only needed in our example code!
+       */
+      sleep(1);
+
+      /* Move the mouse diagonally, 5 units per axis */
+      while (i--) {
+         emit(fd, EV_REL, REL_X, 5);
+         emit(fd, EV_REL, REL_Y, 5);
+         emit(fd, EV_SYN, SYN_REPORT, 0);
+         usleep(15000);
+      }
+
+      /*
+       * Give userspace some time to read the events before we destroy the
+       * device with UI_DEV_DESTROY.
+       */
+      sleep(1);
+
+      ioctl(fd, UI_DEV_DESTROY);
+      close(fd);
+
+      return 0;
+   }
+
+
+uinput old interface
+--------------------
+
+Before uinput version 5, there wasn't a dedicated ioctl to set up a virtual
+device. Programs supporting older versions of uinput interface need to fill
+a uinput_user_dev structure and write it to the uinput file descriptor to
+configure the new uinput device. New code should not use the old interface
+but interact with uinput via ioctl calls, or use libevdev.
+
+.. code-block:: c
+
+   #include <linux/uinput.h>
+
+   /* emit function is identical to of the first example */
+
+   int main(void)
+   {
+      struct uinput_user_dev uud;
+      int version, rc, fd;
+
+      fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
+      rc = ioctl(fd, UI_GET_VERSION, &version);
+
+      if (rc == 0 && version >= 5) {
+         /* use UI_DEV_SETUP */
+         return 0;
+      }
+
+      /*
+       * The ioctls below will enable the device that is about to be
+       * created, to pass key events, in this case the space key.
+       */
+      ioctl(fd, UI_SET_EVBIT, EV_KEY);
+      ioctl(fd, UI_SET_KEYBIT, KEY_SPACE);
+
+      memset(&uud, 0, sizeof(uud));
+      snprintf(uud.name, UINPUT_MAX_NAME_SIZE, "uinput old interface");
+      write(fd, &uud, sizeof(uud));
+
+      ioctl(fd, UI_DEV_CREATE);
+
+      /*
+       * On UI_DEV_CREATE the kernel will create the device node for this
+       * device. We are inserting a pause here so that userspace has time
+       * to detect, initialize the new device, and can start listening to
+       * the event, otherwise it will not notice the event we are about
+       * to send. This pause is only needed in our example code!
+       */
+      sleep(1);
+
+      /* Key press, report the event, send key release, and report again */
+      emit(fd, EV_KEY, KEY_SPACE, 1);
+      emit(fd, EV_SYN, SYN_REPORT, 0);
+      emit(fd, EV_KEY, KEY_SPACE, 0);
+      emit(fd, EV_SYN, SYN_REPORT, 0);
+
+      /*
+       * Give userspace some time to read the events before we destroy the
+       * device with UI_DEV_DESTROY.
+       */
+      sleep(1);
+
+      ioctl(fd, UI_DEV_DESTROY);
+
+      close(fd);
+      return 0;
+   }
+