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, 248 insertions, 0 deletions

diff --git a/drivers/char/nwbutton.c b/drivers/char/nwbutton.c
new file mode 100644
index 000000000..92cee5717
--- /dev/null
+++ b/drivers/char/nwbutton.c
@@ -0,0 +1,248 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 	NetWinder Button Driver-
+ *	Copyright (C) Alex Holden <alex@linuxhacker.org> 1998, 1999.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/sched/signal.h>
+#include <linux/interrupt.h>
+#include <linux/time.h>
+#include <linux/timer.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+
+#include <linux/uaccess.h>
+#include <asm/irq.h>
+#include <asm/mach-types.h>
+
+#define __NWBUTTON_C		/* Tell the header file who we are */
+#include "nwbutton.h"
+
+static void button_sequence_finished(struct timer_list *unused);
+
+static int button_press_count;		/* The count of button presses */
+/* Times for the end of a sequence */
+static DEFINE_TIMER(button_timer, button_sequence_finished);
+static DECLARE_WAIT_QUEUE_HEAD(button_wait_queue); /* Used for blocking read */
+static char button_output_buffer[32];	/* Stores data to write out of device */
+static int bcount;			/* The number of bytes in the buffer */
+static int bdelay = BUTTON_DELAY;	/* The delay, in jiffies */
+static struct button_callback button_callback_list[32]; /* The callback list */
+static int callback_count;		/* The number of callbacks registered */
+static int reboot_count = NUM_PRESSES_REBOOT; /* Number of presses to reboot */
+
+/*
+ * This function is called by other drivers to register a callback function
+ * to be called when a particular number of button presses occurs.
+ * The callback list is a static array of 32 entries (I somehow doubt many
+ * people are ever going to want to register more than 32 different actions
+ * to be performed by the kernel on different numbers of button presses ;).
+ * However, if an attempt to register a 33rd entry (perhaps a stuck loop
+ * somewhere registering the same entry over and over?) it will fail to
+ * do so and return -ENOMEM. If an attempt is made to register a null pointer,
+ * it will fail to do so and return -EINVAL.
+ * Because callbacks can be unregistered at random the list can become
+ * fragmented, so we need to search through the list until we find the first
+ * free entry.
+ *
+ * FIXME: Has anyone spotted any locking functions int his code recently ??
+ */
+
+int button_add_callback (void (*callback) (void), int count)
+{
+	int lp = 0;
+	if (callback_count == 32) {
+		return -ENOMEM;
+	}
+	if (!callback) {
+		return -EINVAL;
+	}
+	callback_count++;
+	for (; (button_callback_list [lp].callback); lp++);
+	button_callback_list [lp].callback = callback;
+	button_callback_list [lp].count = count;
+	return 0;
+}
+
+/*
+ * This function is called by other drivers to deregister a callback function.
+ * If you attempt to unregister a callback which does not exist, it will fail
+ * with -EINVAL. If there is more than one entry with the same address,
+ * because it searches the list from end to beginning, it will unregister the
+ * last one to be registered first (FILO- First In Last Out).
+ * Note that this is not necessarily true if the entries are not submitted
+ * at the same time, because another driver could have unregistered a callback
+ * between the submissions creating a gap earlier in the list, which would
+ * be filled first at submission time.
+ */
+
+int button_del_callback (void (*callback) (void))
+{
+	int lp = 31;
+	if (!callback) {
+		return -EINVAL;
+	}
+	while (lp >= 0) {
+		if ((button_callback_list [lp].callback) == callback) {
+			button_callback_list [lp].callback = NULL;
+			button_callback_list [lp].count = 0;
+			callback_count--;
+			return 0;
+		}
+		lp--;
+	}
+	return -EINVAL;
+}
+
+/*
+ * This function is called by button_sequence_finished to search through the
+ * list of callback functions, and call any of them whose count argument
+ * matches the current count of button presses. It starts at the beginning
+ * of the list and works up to the end. It will refuse to follow a null
+ * pointer (which should never happen anyway).
+ */
+
+static void button_consume_callbacks (int bpcount)
+{
+	int lp = 0;
+	for (; lp <= 31; lp++) {
+		if ((button_callback_list [lp].count) == bpcount) {
+			if (button_callback_list [lp].callback) {
+				button_callback_list[lp].callback();
+			}
+		}
+	}
+}
+
+/* 
+ * This function is called when the button_timer times out.
+ * ie. When you don't press the button for bdelay jiffies, this is taken to
+ * mean you have ended the sequence of key presses, and this function is
+ * called to wind things up (write the press_count out to /dev/button, call
+ * any matching registered function callbacks, initiate reboot, etc.).
+ */
+
+static void button_sequence_finished(struct timer_list *unused)
+{
+	if (IS_ENABLED(CONFIG_NWBUTTON_REBOOT) &&
+	    button_press_count == reboot_count)
+		kill_cad_pid(SIGINT, 1);	/* Ask init to reboot us */
+	button_consume_callbacks (button_press_count);
+	bcount = sprintf (button_output_buffer, "%d\n", button_press_count);
+	button_press_count = 0;		/* Reset the button press counter */
+	wake_up_interruptible (&button_wait_queue);
+}
+
+/* 
+ *  This handler is called when the orange button is pressed (GPIO 10 of the
+ *  SuperIO chip, which maps to logical IRQ 26). If the press_count is 0,
+ *  this is the first press, so it starts a timer and increments the counter.
+ *  If it is higher than 0, it deletes the old timer, starts a new one, and
+ *  increments the counter.
+ */ 
+
+static irqreturn_t button_handler (int irq, void *dev_id)
+{
+	button_press_count++;
+	mod_timer(&button_timer, jiffies + bdelay);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * This function is called when a user space program attempts to read
+ * /dev/nwbutton. It puts the device to sleep on the wait queue until
+ * button_sequence_finished writes some data to the buffer and flushes
+ * the queue, at which point it writes the data out to the device and
+ * returns the number of characters it has written. This function is
+ * reentrant, so that many processes can be attempting to read from the
+ * device at any one time.
+ */
+
+static int button_read (struct file *filp, char __user *buffer,
+			size_t count, loff_t *ppos)
+{
+	DEFINE_WAIT(wait);
+	prepare_to_wait(&button_wait_queue, &wait, TASK_INTERRUPTIBLE);
+	schedule();
+	finish_wait(&button_wait_queue, &wait);
+	return (copy_to_user (buffer, &button_output_buffer, bcount))
+		 ? -EFAULT : bcount;
+}
+
+/* 
+ * This structure is the file operations structure, which specifies what
+ * callbacks functions the kernel should call when a user mode process
+ * attempts to perform these operations on the device.
+ */
+
+static const struct file_operations button_fops = {
+	.owner		= THIS_MODULE,
+	.read		= button_read,
+	.llseek		= noop_llseek,
+};
+
+/* 
+ * This structure is the misc device structure, which specifies the minor
+ * device number (158 in this case), the name of the device (for /proc/misc),
+ * and the address of the above file operations structure.
+ */
+
+static struct miscdevice button_misc_device = {
+	BUTTON_MINOR,
+	"nwbutton",
+	&button_fops,
+};
+
+/*
+ * This function is called to initialise the driver, either from misc.c at
+ * bootup if the driver is compiled into the kernel, or from init_module
+ * below at module insert time. It attempts to register the device node
+ * and the IRQ and fails with a warning message if either fails, though
+ * neither ever should because the device number and IRQ are unique to
+ * this driver.
+ */
+
+static int __init nwbutton_init(void)
+{
+	if (!machine_is_netwinder())
+		return -ENODEV;
+
+	printk (KERN_INFO "NetWinder Button Driver Version %s (C) Alex Holden "
+			"<alex@linuxhacker.org> 1998.\n", VERSION);
+
+	if (misc_register (&button_misc_device)) {
+		printk (KERN_WARNING "nwbutton: Couldn't register device 10, "
+				"%d.\n", BUTTON_MINOR);
+		return -EBUSY;
+	}
+
+	if (request_irq (IRQ_NETWINDER_BUTTON, button_handler, 0,
+			"nwbutton", NULL)) {
+		printk (KERN_WARNING "nwbutton: IRQ %d is not free.\n",
+				IRQ_NETWINDER_BUTTON);
+		misc_deregister (&button_misc_device);
+		return -EIO;
+	}
+	return 0;
+}
+
+static void __exit nwbutton_exit (void) 
+{
+	free_irq (IRQ_NETWINDER_BUTTON, NULL);
+	misc_deregister (&button_misc_device);
+}
+
+
+MODULE_AUTHOR("Alex Holden");
+MODULE_DESCRIPTION("NetWinder button driver");
+MODULE_LICENSE("GPL");
+
+module_init(nwbutton_init);
+module_exit(nwbutton_exit);