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

3 files changed, 471 insertions, 0 deletions

diff --git a/samples/uhid/.gitignore b/samples/uhid/.gitignore
new file mode 100644
index 000000000..0e0a5a929
--- /dev/null
+++ b/samples/uhid/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+/uhid-example
diff --git a/samples/uhid/Makefile b/samples/uhid/Makefile
new file mode 100644
index 000000000..0aa424ec4
--- /dev/null
+++ b/samples/uhid/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+userprogs-always-y += uhid-example
+
+userccflags += -I usr/include
diff --git a/samples/uhid/uhid-example.c b/samples/uhid/uhid-example.c
new file mode 100644
index 000000000..015cb06a2
--- /dev/null
+++ b/samples/uhid/uhid-example.c
@@ -0,0 +1,465 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * UHID Example
+ *
+ * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
+ *
+ * The code may be used by anyone for any purpose,
+ * and can serve as a starting point for developing
+ * applications using uhid.
+ */
+
+/*
+ * UHID Example
+ * This example emulates a basic 3 buttons mouse with wheel over UHID. Run this
+ * program as root and then use the following keys to control the mouse:
+ *   q: Quit the application
+ *   1: Toggle left button (down, up, ...)
+ *   2: Toggle right button
+ *   3: Toggle middle button
+ *   a: Move mouse left
+ *   d: Move mouse right
+ *   w: Move mouse up
+ *   s: Move mouse down
+ *   r: Move wheel up
+ *   f: Move wheel down
+ *
+ * Additionally to 3 button mouse, 3 keyboard LEDs are also supported (LED_NUML,
+ * LED_CAPSL and LED_SCROLLL). The device doesn't generate any related keyboard
+ * events, though. You need to manually write the EV_LED/LED_XY/1 activation
+ * input event to the evdev device to see it being sent to this device.
+ *
+ * If uhid is not available as /dev/uhid, then you can pass a different path as
+ * first argument.
+ * If <linux/uhid.h> is not installed in /usr, then compile this with:
+ *   gcc -o ./uhid_test -Wall -I./include ./samples/uhid/uhid-example.c
+ * And ignore the warning about kernel headers. However, it is recommended to
+ * use the installed uhid.h if available.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <termios.h>
+#include <unistd.h>
+#include <linux/uhid.h>
+
+/*
+ * HID Report Desciptor
+ * We emulate a basic 3 button mouse with wheel and 3 keyboard LEDs. This is
+ * the report-descriptor as the kernel will parse it:
+ *
+ * INPUT(1)[INPUT]
+ *   Field(0)
+ *     Physical(GenericDesktop.Pointer)
+ *     Application(GenericDesktop.Mouse)
+ *     Usage(3)
+ *       Button.0001
+ *       Button.0002
+ *       Button.0003
+ *     Logical Minimum(0)
+ *     Logical Maximum(1)
+ *     Report Size(1)
+ *     Report Count(3)
+ *     Report Offset(0)
+ *     Flags( Variable Absolute )
+ *   Field(1)
+ *     Physical(GenericDesktop.Pointer)
+ *     Application(GenericDesktop.Mouse)
+ *     Usage(3)
+ *       GenericDesktop.X
+ *       GenericDesktop.Y
+ *       GenericDesktop.Wheel
+ *     Logical Minimum(-128)
+ *     Logical Maximum(127)
+ *     Report Size(8)
+ *     Report Count(3)
+ *     Report Offset(8)
+ *     Flags( Variable Relative )
+ * OUTPUT(2)[OUTPUT]
+ *   Field(0)
+ *     Application(GenericDesktop.Keyboard)
+ *     Usage(3)
+ *       LED.NumLock
+ *       LED.CapsLock
+ *       LED.ScrollLock
+ *     Logical Minimum(0)
+ *     Logical Maximum(1)
+ *     Report Size(1)
+ *     Report Count(3)
+ *     Report Offset(0)
+ *     Flags( Variable Absolute )
+ *
+ * This is the mapping that we expect:
+ *   Button.0001 ---> Key.LeftBtn
+ *   Button.0002 ---> Key.RightBtn
+ *   Button.0003 ---> Key.MiddleBtn
+ *   GenericDesktop.X ---> Relative.X
+ *   GenericDesktop.Y ---> Relative.Y
+ *   GenericDesktop.Wheel ---> Relative.Wheel
+ *   LED.NumLock ---> LED.NumLock
+ *   LED.CapsLock ---> LED.CapsLock
+ *   LED.ScrollLock ---> LED.ScrollLock
+ *
+ * This information can be verified by reading /sys/kernel/debug/hid/<dev>/rdesc
+ * This file should print the same information as showed above.
+ */
+
+static unsigned char rdesc[] = {
+	0x05, 0x01,	/* USAGE_PAGE (Generic Desktop) */
+	0x09, 0x02,	/* USAGE (Mouse) */
+	0xa1, 0x01,	/* COLLECTION (Application) */
+	0x09, 0x01,		/* USAGE (Pointer) */
+	0xa1, 0x00,		/* COLLECTION (Physical) */
+	0x85, 0x01,			/* REPORT_ID (1) */
+	0x05, 0x09,			/* USAGE_PAGE (Button) */
+	0x19, 0x01,			/* USAGE_MINIMUM (Button 1) */
+	0x29, 0x03,			/* USAGE_MAXIMUM (Button 3) */
+	0x15, 0x00,			/* LOGICAL_MINIMUM (0) */
+	0x25, 0x01,			/* LOGICAL_MAXIMUM (1) */
+	0x95, 0x03,			/* REPORT_COUNT (3) */
+	0x75, 0x01,			/* REPORT_SIZE (1) */
+	0x81, 0x02,			/* INPUT (Data,Var,Abs) */
+	0x95, 0x01,			/* REPORT_COUNT (1) */
+	0x75, 0x05,			/* REPORT_SIZE (5) */
+	0x81, 0x01,			/* INPUT (Cnst,Var,Abs) */
+	0x05, 0x01,			/* USAGE_PAGE (Generic Desktop) */
+	0x09, 0x30,			/* USAGE (X) */
+	0x09, 0x31,			/* USAGE (Y) */
+	0x09, 0x38,			/* USAGE (WHEEL) */
+	0x15, 0x81,			/* LOGICAL_MINIMUM (-127) */
+	0x25, 0x7f,			/* LOGICAL_MAXIMUM (127) */
+	0x75, 0x08,			/* REPORT_SIZE (8) */
+	0x95, 0x03,			/* REPORT_COUNT (3) */
+	0x81, 0x06,			/* INPUT (Data,Var,Rel) */
+	0xc0,			/* END_COLLECTION */
+	0xc0,		/* END_COLLECTION */
+	0x05, 0x01,	/* USAGE_PAGE (Generic Desktop) */
+	0x09, 0x06,	/* USAGE (Keyboard) */
+	0xa1, 0x01,	/* COLLECTION (Application) */
+	0x85, 0x02,		/* REPORT_ID (2) */
+	0x05, 0x08,		/* USAGE_PAGE (Led) */
+	0x19, 0x01,		/* USAGE_MINIMUM (1) */
+	0x29, 0x03,		/* USAGE_MAXIMUM (3) */
+	0x15, 0x00,		/* LOGICAL_MINIMUM (0) */
+	0x25, 0x01,		/* LOGICAL_MAXIMUM (1) */
+	0x95, 0x03,		/* REPORT_COUNT (3) */
+	0x75, 0x01,		/* REPORT_SIZE (1) */
+	0x91, 0x02,		/* Output (Data,Var,Abs) */
+	0x95, 0x01,		/* REPORT_COUNT (1) */
+	0x75, 0x05,		/* REPORT_SIZE (5) */
+	0x91, 0x01,		/* Output (Cnst,Var,Abs) */
+	0xc0,		/* END_COLLECTION */
+};
+
+static int uhid_write(int fd, const struct uhid_event *ev)
+{
+	ssize_t ret;
+
+	ret = write(fd, ev, sizeof(*ev));
+	if (ret < 0) {
+		fprintf(stderr, "Cannot write to uhid: %m\n");
+		return -errno;
+	} else if (ret != sizeof(*ev)) {
+		fprintf(stderr, "Wrong size written to uhid: %zd != %zu\n",
+			ret, sizeof(ev));
+		return -EFAULT;
+	} else {
+		return 0;
+	}
+}
+
+static int create(int fd)
+{
+	struct uhid_event ev;
+
+	memset(&ev, 0, sizeof(ev));
+	ev.type = UHID_CREATE;
+	strcpy((char*)ev.u.create.name, "test-uhid-device");
+	ev.u.create.rd_data = rdesc;
+	ev.u.create.rd_size = sizeof(rdesc);
+	ev.u.create.bus = BUS_USB;
+	ev.u.create.vendor = 0x15d9;
+	ev.u.create.product = 0x0a37;
+	ev.u.create.version = 0;
+	ev.u.create.country = 0;
+
+	return uhid_write(fd, &ev);
+}
+
+static void destroy(int fd)
+{
+	struct uhid_event ev;
+
+	memset(&ev, 0, sizeof(ev));
+	ev.type = UHID_DESTROY;
+
+	uhid_write(fd, &ev);
+}
+
+/* This parses raw output reports sent by the kernel to the device. A normal
+ * uhid program shouldn't do this but instead just forward the raw report.
+ * However, for ducomentational purposes, we try to detect LED events here and
+ * print debug messages for it. */
+static void handle_output(struct uhid_event *ev)
+{
+	/* LED messages are adverised via OUTPUT reports; ignore the rest */
+	if (ev->u.output.rtype != UHID_OUTPUT_REPORT)
+		return;
+	/* LED reports have length 2 bytes */
+	if (ev->u.output.size != 2)
+		return;
+	/* first byte is report-id which is 0x02 for LEDs in our rdesc */
+	if (ev->u.output.data[0] != 0x2)
+		return;
+
+	/* print flags payload */
+	fprintf(stderr, "LED output report received with flags %x\n",
+		ev->u.output.data[1]);
+}
+
+static int event(int fd)
+{
+	struct uhid_event ev;
+	ssize_t ret;
+
+	memset(&ev, 0, sizeof(ev));
+	ret = read(fd, &ev, sizeof(ev));
+	if (ret == 0) {
+		fprintf(stderr, "Read HUP on uhid-cdev\n");
+		return -EFAULT;
+	} else if (ret < 0) {
+		fprintf(stderr, "Cannot read uhid-cdev: %m\n");
+		return -errno;
+	} else if (ret != sizeof(ev)) {
+		fprintf(stderr, "Invalid size read from uhid-dev: %zd != %zu\n",
+			ret, sizeof(ev));
+		return -EFAULT;
+	}
+
+	switch (ev.type) {
+	case UHID_START:
+		fprintf(stderr, "UHID_START from uhid-dev\n");
+		break;
+	case UHID_STOP:
+		fprintf(stderr, "UHID_STOP from uhid-dev\n");
+		break;
+	case UHID_OPEN:
+		fprintf(stderr, "UHID_OPEN from uhid-dev\n");
+		break;
+	case UHID_CLOSE:
+		fprintf(stderr, "UHID_CLOSE from uhid-dev\n");
+		break;
+	case UHID_OUTPUT:
+		fprintf(stderr, "UHID_OUTPUT from uhid-dev\n");
+		handle_output(&ev);
+		break;
+	case UHID_OUTPUT_EV:
+		fprintf(stderr, "UHID_OUTPUT_EV from uhid-dev\n");
+		break;
+	default:
+		fprintf(stderr, "Invalid event from uhid-dev: %u\n", ev.type);
+	}
+
+	return 0;
+}
+
+static bool btn1_down;
+static bool btn2_down;
+static bool btn3_down;
+static signed char abs_hor;
+static signed char abs_ver;
+static signed char wheel;
+
+static int send_event(int fd)
+{
+	struct uhid_event ev;
+
+	memset(&ev, 0, sizeof(ev));
+	ev.type = UHID_INPUT;
+	ev.u.input.size = 5;
+
+	ev.u.input.data[0] = 0x1;
+	if (btn1_down)
+		ev.u.input.data[1] |= 0x1;
+	if (btn2_down)
+		ev.u.input.data[1] |= 0x2;
+	if (btn3_down)
+		ev.u.input.data[1] |= 0x4;
+
+	ev.u.input.data[2] = abs_hor;
+	ev.u.input.data[3] = abs_ver;
+	ev.u.input.data[4] = wheel;
+
+	return uhid_write(fd, &ev);
+}
+
+static int keyboard(int fd)
+{
+	char buf[128];
+	ssize_t ret, i;
+
+	ret = read(STDIN_FILENO, buf, sizeof(buf));
+	if (ret == 0) {
+		fprintf(stderr, "Read HUP on stdin\n");
+		return -EFAULT;
+	} else if (ret < 0) {
+		fprintf(stderr, "Cannot read stdin: %m\n");
+		return -errno;
+	}
+
+	for (i = 0; i < ret; ++i) {
+		switch (buf[i]) {
+		case '1':
+			btn1_down = !btn1_down;
+			ret = send_event(fd);
+			if (ret)
+				return ret;
+			break;
+		case '2':
+			btn2_down = !btn2_down;
+			ret = send_event(fd);
+			if (ret)
+				return ret;
+			break;
+		case '3':
+			btn3_down = !btn3_down;
+			ret = send_event(fd);
+			if (ret)
+				return ret;
+			break;
+		case 'a':
+			abs_hor = -20;
+			ret = send_event(fd);
+			abs_hor = 0;
+			if (ret)
+				return ret;
+			break;
+		case 'd':
+			abs_hor = 20;
+			ret = send_event(fd);
+			abs_hor = 0;
+			if (ret)
+				return ret;
+			break;
+		case 'w':
+			abs_ver = -20;
+			ret = send_event(fd);
+			abs_ver = 0;
+			if (ret)
+				return ret;
+			break;
+		case 's':
+			abs_ver = 20;
+			ret = send_event(fd);
+			abs_ver = 0;
+			if (ret)
+				return ret;
+			break;
+		case 'r':
+			wheel = 1;
+			ret = send_event(fd);
+			wheel = 0;
+			if (ret)
+				return ret;
+			break;
+		case 'f':
+			wheel = -1;
+			ret = send_event(fd);
+			wheel = 0;
+			if (ret)
+				return ret;
+			break;
+		case 'q':
+			return -ECANCELED;
+		default:
+			fprintf(stderr, "Invalid input: %c\n", buf[i]);
+		}
+	}
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int fd;
+	const char *path = "/dev/uhid";
+	struct pollfd pfds[2];
+	int ret;
+	struct termios state;
+
+	ret = tcgetattr(STDIN_FILENO, &state);
+	if (ret) {
+		fprintf(stderr, "Cannot get tty state\n");
+	} else {
+		state.c_lflag &= ~ICANON;
+		state.c_cc[VMIN] = 1;
+		ret = tcsetattr(STDIN_FILENO, TCSANOW, &state);
+		if (ret)
+			fprintf(stderr, "Cannot set tty state\n");
+	}
+
+	if (argc >= 2) {
+		if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help")) {
+			fprintf(stderr, "Usage: %s [%s]\n", argv[0], path);
+			return EXIT_SUCCESS;
+		} else {
+			path = argv[1];
+		}
+	}
+
+	fprintf(stderr, "Open uhid-cdev %s\n", path);
+	fd = open(path, O_RDWR | O_CLOEXEC);
+	if (fd < 0) {
+		fprintf(stderr, "Cannot open uhid-cdev %s: %m\n", path);
+		return EXIT_FAILURE;
+	}
+
+	fprintf(stderr, "Create uhid device\n");
+	ret = create(fd);
+	if (ret) {
+		close(fd);
+		return EXIT_FAILURE;
+	}
+
+	pfds[0].fd = STDIN_FILENO;
+	pfds[0].events = POLLIN;
+	pfds[1].fd = fd;
+	pfds[1].events = POLLIN;
+
+	fprintf(stderr, "Press 'q' to quit...\n");
+	while (1) {
+		ret = poll(pfds, 2, -1);
+		if (ret < 0) {
+			fprintf(stderr, "Cannot poll for fds: %m\n");
+			break;
+		}
+		if (pfds[0].revents & POLLHUP) {
+			fprintf(stderr, "Received HUP on stdin\n");
+			break;
+		}
+		if (pfds[1].revents & POLLHUP) {
+			fprintf(stderr, "Received HUP on uhid-cdev\n");
+			break;
+		}
+
+		if (pfds[0].revents & POLLIN) {
+			ret = keyboard(fd);
+			if (ret)
+				break;
+		}
+		if (pfds[1].revents & POLLIN) {
+			ret = event(fd);
+			if (ret)
+				break;
+		}
+	}
+
+	fprintf(stderr, "Destroy uhid device\n");
+	destroy(fd);
+	return EXIT_SUCCESS;
+}