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, 505 insertions, 0 deletions

diff --git a/drivers/base/attribute_container.c b/drivers/base/attribute_container.c
new file mode 100644
index 000000000..3c4563742
--- /dev/null
+++ b/drivers/base/attribute_container.c
@@ -0,0 +1,505 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * attribute_container.c - implementation of a simple container for classes
+ *
+ * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com>
+ *
+ * The basic idea here is to enable a device to be attached to an
+ * aritrary numer of classes without having to allocate storage for them.
+ * Instead, the contained classes select the devices they need to attach
+ * to via a matching function.
+ */
+
+#include <linux/attribute_container.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+
+#include "base.h"
+
+/* This is a private structure used to tie the classdev and the
+ * container .. it should never be visible outside this file */
+struct internal_container {
+	struct klist_node node;
+	struct attribute_container *cont;
+	struct device classdev;
+};
+
+static void internal_container_klist_get(struct klist_node *n)
+{
+	struct internal_container *ic =
+		container_of(n, struct internal_container, node);
+	get_device(&ic->classdev);
+}
+
+static void internal_container_klist_put(struct klist_node *n)
+{
+	struct internal_container *ic =
+		container_of(n, struct internal_container, node);
+	put_device(&ic->classdev);
+}
+
+
+/**
+ * attribute_container_classdev_to_container - given a classdev, return the container
+ *
+ * @classdev: the class device created by attribute_container_add_device.
+ *
+ * Returns the container associated with this classdev.
+ */
+struct attribute_container *
+attribute_container_classdev_to_container(struct device *classdev)
+{
+	struct internal_container *ic =
+		container_of(classdev, struct internal_container, classdev);
+	return ic->cont;
+}
+EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
+
+static LIST_HEAD(attribute_container_list);
+
+static DEFINE_MUTEX(attribute_container_mutex);
+
+/**
+ * attribute_container_register - register an attribute container
+ *
+ * @cont: The container to register.  This must be allocated by the
+ *        callee and should also be zeroed by it.
+ */
+void
+attribute_container_register(struct attribute_container *cont)
+{
+	INIT_LIST_HEAD(&cont->node);
+	klist_init(&cont->containers, internal_container_klist_get,
+		   internal_container_klist_put);
+
+	mutex_lock(&attribute_container_mutex);
+	list_add_tail(&cont->node, &attribute_container_list);
+	mutex_unlock(&attribute_container_mutex);
+}
+EXPORT_SYMBOL_GPL(attribute_container_register);
+
+/**
+ * attribute_container_unregister - remove a container registration
+ *
+ * @cont: previously registered container to remove
+ */
+int
+attribute_container_unregister(struct attribute_container *cont)
+{
+	int retval = -EBUSY;
+
+	mutex_lock(&attribute_container_mutex);
+	spin_lock(&cont->containers.k_lock);
+	if (!list_empty(&cont->containers.k_list))
+		goto out;
+	retval = 0;
+	list_del(&cont->node);
+ out:
+	spin_unlock(&cont->containers.k_lock);
+	mutex_unlock(&attribute_container_mutex);
+	return retval;
+
+}
+EXPORT_SYMBOL_GPL(attribute_container_unregister);
+
+/* private function used as class release */
+static void attribute_container_release(struct device *classdev)
+{
+	struct internal_container *ic
+		= container_of(classdev, struct internal_container, classdev);
+	struct device *dev = classdev->parent;
+
+	kfree(ic);
+	put_device(dev);
+}
+
+/**
+ * attribute_container_add_device - see if any container is interested in dev
+ *
+ * @dev: device to add attributes to
+ * @fn:	 function to trigger addition of class device.
+ *
+ * This function allocates storage for the class device(s) to be
+ * attached to dev (one for each matching attribute_container).  If no
+ * fn is provided, the code will simply register the class device via
+ * device_add.  If a function is provided, it is expected to add
+ * the class device at the appropriate time.  One of the things that
+ * might be necessary is to allocate and initialise the classdev and
+ * then add it a later time.  To do this, call this routine for
+ * allocation and initialisation and then use
+ * attribute_container_device_trigger() to call device_add() on
+ * it.  Note: after this, the class device contains a reference to dev
+ * which is not relinquished until the release of the classdev.
+ */
+void
+attribute_container_add_device(struct device *dev,
+			       int (*fn)(struct attribute_container *,
+					 struct device *,
+					 struct device *))
+{
+	struct attribute_container *cont;
+
+	mutex_lock(&attribute_container_mutex);
+	list_for_each_entry(cont, &attribute_container_list, node) {
+		struct internal_container *ic;
+
+		if (attribute_container_no_classdevs(cont))
+			continue;
+
+		if (!cont->match(cont, dev))
+			continue;
+
+		ic = kzalloc_obj(*ic);
+		if (!ic) {
+			dev_err(dev, "failed to allocate class container\n");
+			continue;
+		}
+
+		ic->cont = cont;
+		device_initialize(&ic->classdev);
+		ic->classdev.parent = get_device(dev);
+		ic->classdev.class = cont->class;
+		cont->class->dev_release = attribute_container_release;
+		dev_set_name(&ic->classdev, "%s", dev_name(dev));
+		if (fn)
+			fn(cont, dev, &ic->classdev);
+		else
+			attribute_container_add_class_device(&ic->classdev);
+		klist_add_tail(&ic->node, &cont->containers);
+	}
+	mutex_unlock(&attribute_container_mutex);
+}
+
+/* FIXME: can't break out of this unless klist_iter_exit is also
+ * called before doing the break
+ */
+#define klist_for_each_entry(pos, head, member, iter) \
+	for (klist_iter_init(head, iter); (pos = ({ \
+		struct klist_node *n = klist_next(iter); \
+		n ? container_of(n, typeof(*pos), member) : \
+			({ klist_iter_exit(iter) ; NULL; }); \
+	})) != NULL;)
+
+
+/**
+ * attribute_container_remove_device - make device eligible for removal.
+ *
+ * @dev:  The generic device
+ * @fn:	  A function to call to remove the device
+ *
+ * This routine triggers device removal.  If fn is NULL, then it is
+ * simply done via device_unregister (note that if something
+ * still has a reference to the classdev, then the memory occupied
+ * will not be freed until the classdev is released).  If you want a
+ * two phase release: remove from visibility and then delete the
+ * device, then you should use this routine with a fn that calls
+ * device_del() and then use attribute_container_device_trigger()
+ * to do the final put on the classdev.
+ */
+void
+attribute_container_remove_device(struct device *dev,
+				  void (*fn)(struct attribute_container *,
+					     struct device *,
+					     struct device *))
+{
+	struct attribute_container *cont;
+
+	mutex_lock(&attribute_container_mutex);
+	list_for_each_entry(cont, &attribute_container_list, node) {
+		struct internal_container *ic;
+		struct klist_iter iter;
+
+		if (attribute_container_no_classdevs(cont))
+			continue;
+
+		if (!cont->match(cont, dev))
+			continue;
+
+		klist_for_each_entry(ic, &cont->containers, node, &iter) {
+			if (dev != ic->classdev.parent)
+				continue;
+			klist_del(&ic->node);
+			if (fn)
+				fn(cont, dev, &ic->classdev);
+			else {
+				attribute_container_remove_attrs(&ic->classdev);
+				device_unregister(&ic->classdev);
+			}
+		}
+	}
+	mutex_unlock(&attribute_container_mutex);
+}
+
+static int
+do_attribute_container_device_trigger_safe(struct device *dev,
+					   struct attribute_container *cont,
+					   int (*fn)(struct attribute_container *,
+						     struct device *, struct device *),
+					   int (*undo)(struct attribute_container *,
+						       struct device *, struct device *))
+{
+	int ret;
+	struct internal_container *ic, *failed;
+	struct klist_iter iter;
+
+	if (attribute_container_no_classdevs(cont))
+		return fn(cont, dev, NULL);
+
+	klist_for_each_entry(ic, &cont->containers, node, &iter) {
+		if (dev == ic->classdev.parent) {
+			ret = fn(cont, dev, &ic->classdev);
+			if (ret) {
+				failed = ic;
+				klist_iter_exit(&iter);
+				goto fail;
+			}
+		}
+	}
+	return 0;
+
+fail:
+	if (!undo)
+		return ret;
+
+	/* Attempt to undo the work partially done. */
+	klist_for_each_entry(ic, &cont->containers, node, &iter) {
+		if (ic == failed) {
+			klist_iter_exit(&iter);
+			break;
+		}
+		if (dev == ic->classdev.parent)
+			undo(cont, dev, &ic->classdev);
+	}
+	return ret;
+}
+
+/**
+ * attribute_container_device_trigger_safe - execute a trigger for each
+ * matching classdev or fail all of them.
+ *
+ * @dev:  The generic device to run the trigger for
+ * @fn:   the function to execute for each classdev.
+ * @undo: A function to undo the work previously done in case of error
+ *
+ * This function is a safe version of
+ * attribute_container_device_trigger. It stops on the first error and
+ * undo the partial work that has been done, on previous classdev.  It
+ * is guaranteed that either they all succeeded, or none of them
+ * succeeded.
+ */
+int
+attribute_container_device_trigger_safe(struct device *dev,
+					int (*fn)(struct attribute_container *,
+						  struct device *,
+						  struct device *),
+					int (*undo)(struct attribute_container *,
+						    struct device *,
+						    struct device *))
+{
+	struct attribute_container *cont, *failed = NULL;
+	int ret = 0;
+
+	mutex_lock(&attribute_container_mutex);
+
+	list_for_each_entry(cont, &attribute_container_list, node) {
+
+		if (!cont->match(cont, dev))
+			continue;
+
+		ret = do_attribute_container_device_trigger_safe(dev, cont,
+								 fn, undo);
+		if (ret) {
+			failed = cont;
+			break;
+		}
+	}
+
+	if (ret && !WARN_ON(!undo)) {
+		list_for_each_entry(cont, &attribute_container_list, node) {
+
+			if (failed == cont)
+				break;
+
+			if (!cont->match(cont, dev))
+				continue;
+
+			do_attribute_container_device_trigger_safe(dev, cont,
+								   undo, NULL);
+		}
+	}
+
+	mutex_unlock(&attribute_container_mutex);
+	return ret;
+
+}
+
+/**
+ * attribute_container_device_trigger - execute a trigger for each matching classdev
+ *
+ * @dev:  The generic device to run the trigger for
+ * @fn:   the function to execute for each classdev.
+ *
+ * This function is for executing a trigger when you need to know both
+ * the container and the classdev.
+ */
+void
+attribute_container_device_trigger(struct device *dev,
+				   int (*fn)(struct attribute_container *,
+					     struct device *,
+					     struct device *))
+{
+	struct attribute_container *cont;
+
+	mutex_lock(&attribute_container_mutex);
+	list_for_each_entry(cont, &attribute_container_list, node) {
+		struct internal_container *ic;
+		struct klist_iter iter;
+
+		if (!cont->match(cont, dev))
+			continue;
+
+		if (attribute_container_no_classdevs(cont)) {
+			fn(cont, dev, NULL);
+			continue;
+		}
+
+		klist_for_each_entry(ic, &cont->containers, node, &iter) {
+			if (dev == ic->classdev.parent)
+				fn(cont, dev, &ic->classdev);
+		}
+	}
+	mutex_unlock(&attribute_container_mutex);
+}
+
+/**
+ * attribute_container_add_attrs - add attributes
+ *
+ * @classdev: The class device
+ *
+ * This simply creates all the class device sysfs files from the
+ * attributes listed in the container
+ */
+int
+attribute_container_add_attrs(struct device *classdev)
+{
+	struct attribute_container *cont =
+		attribute_container_classdev_to_container(classdev);
+	struct device_attribute **attrs = cont->attrs;
+	int i, error;
+
+	BUG_ON(attrs && cont->grp);
+
+	if (!attrs && !cont->grp)
+		return 0;
+
+	if (cont->grp)
+		return sysfs_create_group(&classdev->kobj, cont->grp);
+
+	for (i = 0; attrs[i]; i++) {
+		sysfs_attr_init(&attrs[i]->attr);
+		error = device_create_file(classdev, attrs[i]);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+/**
+ * attribute_container_add_class_device - same function as device_add
+ *
+ * @classdev:	the class device to add
+ *
+ * This performs essentially the same function as device_add except for
+ * attribute containers, namely add the classdev to the system and then
+ * create the attribute files
+ */
+int
+attribute_container_add_class_device(struct device *classdev)
+{
+	int error = device_add(classdev);
+
+	if (error)
+		return error;
+
+	error = attribute_container_add_attrs(classdev);
+	if (error)
+		device_del(classdev);
+
+	return error;
+}
+
+/**
+ * attribute_container_remove_attrs - remove any attribute files
+ *
+ * @classdev: The class device to remove the files from
+ *
+ */
+void
+attribute_container_remove_attrs(struct device *classdev)
+{
+	struct attribute_container *cont =
+		attribute_container_classdev_to_container(classdev);
+	struct device_attribute **attrs = cont->attrs;
+	int i;
+
+	if (!attrs && !cont->grp)
+		return;
+
+	if (cont->grp) {
+		sysfs_remove_group(&classdev->kobj, cont->grp);
+		return ;
+	}
+
+	for (i = 0; attrs[i]; i++)
+		device_remove_file(classdev, attrs[i]);
+}
+
+/**
+ * attribute_container_class_device_del - equivalent of class_device_del
+ *
+ * @classdev: the class device
+ *
+ * This function simply removes all the attribute files and then calls
+ * device_del.
+ */
+void
+attribute_container_class_device_del(struct device *classdev)
+{
+	attribute_container_remove_attrs(classdev);
+	device_del(classdev);
+}
+
+/**
+ * attribute_container_find_class_device - find the corresponding class_device
+ *
+ * @cont:	the container
+ * @dev:	the generic device
+ *
+ * Looks up the device in the container's list of class devices and returns
+ * the corresponding class_device.
+ */
+struct device *
+attribute_container_find_class_device(struct attribute_container *cont,
+				      struct device *dev)
+{
+	struct device *cdev = NULL;
+	struct internal_container *ic;
+	struct klist_iter iter;
+
+	klist_for_each_entry(ic, &cont->containers, node, &iter) {
+		if (ic->classdev.parent == dev) {
+			cdev = &ic->classdev;
+			/* FIXME: must exit iterator then break */
+			klist_iter_exit(&iter);
+			break;
+		}
+	}
+
+	return cdev;
+}
+EXPORT_SYMBOL_GPL(attribute_container_find_class_device);