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, 375 insertions, 0 deletions

diff --git a/lib/parman.c b/lib/parman.c
new file mode 100644
index 000000000..0de691c20
--- /dev/null
+++ b/lib/parman.c
@@ -0,0 +1,375 @@
+/*
+ * lib/parman.c - Manager for linear priority array areas
+ * Copyright (c) 2017 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2017 Jiri Pirko <jiri@mellanox.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/list.h>
+#include <linux/err.h>
+#include <linux/parman.h>
+
+struct parman_algo {
+	int (*item_add)(struct parman *parman, struct parman_prio *prio,
+			struct parman_item *item);
+	void (*item_remove)(struct parman *parman, struct parman_prio *prio,
+			    struct parman_item *item);
+};
+
+struct parman {
+	const struct parman_ops *ops;
+	void *priv;
+	const struct parman_algo *algo;
+	unsigned long count;
+	unsigned long limit_count;
+	struct list_head prio_list;
+};
+
+static int parman_enlarge(struct parman *parman)
+{
+	unsigned long new_count = parman->limit_count +
+				  parman->ops->resize_step;
+	int err;
+
+	err = parman->ops->resize(parman->priv, new_count);
+	if (err)
+		return err;
+	parman->limit_count = new_count;
+	return 0;
+}
+
+static int parman_shrink(struct parman *parman)
+{
+	unsigned long new_count = parman->limit_count -
+				  parman->ops->resize_step;
+	int err;
+
+	if (new_count < parman->ops->base_count)
+		return 0;
+	err = parman->ops->resize(parman->priv, new_count);
+	if (err)
+		return err;
+	parman->limit_count = new_count;
+	return 0;
+}
+
+static bool parman_prio_used(struct parman_prio *prio)
+{
+	return !list_empty(&prio->item_list);
+}
+
+static struct parman_item *parman_prio_first_item(struct parman_prio *prio)
+{
+	return list_first_entry(&prio->item_list,
+				typeof(struct parman_item), list);
+}
+
+static unsigned long parman_prio_first_index(struct parman_prio *prio)
+{
+	return parman_prio_first_item(prio)->index;
+}
+
+static struct parman_item *parman_prio_last_item(struct parman_prio *prio)
+{
+	return list_last_entry(&prio->item_list,
+			       typeof(struct parman_item), list);
+}
+
+static unsigned long parman_prio_last_index(struct parman_prio *prio)
+{
+	return parman_prio_last_item(prio)->index;
+}
+
+static unsigned long parman_lsort_new_index_find(struct parman *parman,
+						 struct parman_prio *prio)
+{
+	list_for_each_entry_from_reverse(prio, &parman->prio_list, list) {
+		if (!parman_prio_used(prio))
+			continue;
+		return parman_prio_last_index(prio) + 1;
+	}
+	return 0;
+}
+
+static void __parman_prio_move(struct parman *parman, struct parman_prio *prio,
+			       struct parman_item *item, unsigned long to_index,
+			       unsigned long count)
+{
+	parman->ops->move(parman->priv, item->index, to_index, count);
+}
+
+static void parman_prio_shift_down(struct parman *parman,
+				   struct parman_prio *prio)
+{
+	struct parman_item *item;
+	unsigned long to_index;
+
+	if (!parman_prio_used(prio))
+		return;
+	item = parman_prio_first_item(prio);
+	to_index = parman_prio_last_index(prio) + 1;
+	__parman_prio_move(parman, prio, item, to_index, 1);
+	list_move_tail(&item->list, &prio->item_list);
+	item->index = to_index;
+}
+
+static void parman_prio_shift_up(struct parman *parman,
+				 struct parman_prio *prio)
+{
+	struct parman_item *item;
+	unsigned long to_index;
+
+	if (!parman_prio_used(prio))
+		return;
+	item = parman_prio_last_item(prio);
+	to_index = parman_prio_first_index(prio) - 1;
+	__parman_prio_move(parman, prio, item, to_index, 1);
+	list_move(&item->list, &prio->item_list);
+	item->index = to_index;
+}
+
+static void parman_prio_item_remove(struct parman *parman,
+				    struct parman_prio *prio,
+				    struct parman_item *item)
+{
+	struct parman_item *last_item;
+	unsigned long to_index;
+
+	last_item = parman_prio_last_item(prio);
+	if (last_item == item) {
+		list_del(&item->list);
+		return;
+	}
+	to_index = item->index;
+	__parman_prio_move(parman, prio, last_item, to_index, 1);
+	list_del(&last_item->list);
+	list_replace(&item->list, &last_item->list);
+	last_item->index = to_index;
+}
+
+static int parman_lsort_item_add(struct parman *parman,
+				 struct parman_prio *prio,
+				 struct parman_item *item)
+{
+	struct parman_prio *prio2;
+	unsigned long new_index;
+	int err;
+
+	if (parman->count + 1 > parman->limit_count) {
+		err = parman_enlarge(parman);
+		if (err)
+			return err;
+	}
+
+	new_index = parman_lsort_new_index_find(parman, prio);
+	list_for_each_entry_reverse(prio2, &parman->prio_list, list) {
+		if (prio2 == prio)
+			break;
+		parman_prio_shift_down(parman, prio2);
+	}
+	item->index = new_index;
+	list_add_tail(&item->list, &prio->item_list);
+	parman->count++;
+	return 0;
+}
+
+static void parman_lsort_item_remove(struct parman *parman,
+				     struct parman_prio *prio,
+				     struct parman_item *item)
+{
+	parman_prio_item_remove(parman, prio, item);
+	list_for_each_entry_continue(prio, &parman->prio_list, list)
+		parman_prio_shift_up(parman, prio);
+	parman->count--;
+	if (parman->limit_count - parman->count >= parman->ops->resize_step)
+		parman_shrink(parman);
+}
+
+static const struct parman_algo parman_lsort = {
+	.item_add	= parman_lsort_item_add,
+	.item_remove	= parman_lsort_item_remove,
+};
+
+static const struct parman_algo *parman_algos[] = {
+	&parman_lsort,
+};
+
+/**
+ * parman_create - creates a new parman instance
+ * @ops:	caller-specific callbacks
+ * @priv:	pointer to a private data passed to the ops
+ *
+ * Note: all locking must be provided by the caller.
+ *
+ * Each parman instance manages an array area with chunks of entries
+ * with the same priority. Consider following example:
+ *
+ * item 1 with prio 10
+ * item 2 with prio 10
+ * item 3 with prio 10
+ * item 4 with prio 20
+ * item 5 with prio 20
+ * item 6 with prio 30
+ * item 7 with prio 30
+ * item 8 with prio 30
+ *
+ * In this example, there are 3 priority chunks. The order of the priorities
+ * matters, however the order of items within a single priority chunk does not
+ * matter. So the same array could be ordered as follows:
+ *
+ * item 2 with prio 10
+ * item 3 with prio 10
+ * item 1 with prio 10
+ * item 5 with prio 20
+ * item 4 with prio 20
+ * item 7 with prio 30
+ * item 8 with prio 30
+ * item 6 with prio 30
+ *
+ * The goal of parman is to maintain the priority ordering. The caller
+ * provides @ops with callbacks parman uses to move the items
+ * and resize the array area.
+ *
+ * Returns a pointer to newly created parman instance in case of success,
+ * otherwise it returns NULL.
+ */
+struct parman *parman_create(const struct parman_ops *ops, void *priv)
+{
+	struct parman *parman;
+
+	parman = kzalloc_obj(*parman);
+	if (!parman)
+		return NULL;
+	INIT_LIST_HEAD(&parman->prio_list);
+	parman->ops = ops;
+	parman->priv = priv;
+	parman->limit_count = ops->base_count;
+	parman->algo = parman_algos[ops->algo];
+	return parman;
+}
+EXPORT_SYMBOL(parman_create);
+
+/**
+ * parman_destroy - destroys existing parman instance
+ * @parman:	parman instance
+ *
+ * Note: all locking must be provided by the caller.
+ */
+void parman_destroy(struct parman *parman)
+{
+	WARN_ON(!list_empty(&parman->prio_list));
+	kfree(parman);
+}
+EXPORT_SYMBOL(parman_destroy);
+
+/**
+ * parman_prio_init - initializes a parman priority chunk
+ * @parman:	parman instance
+ * @prio:	parman prio structure to be initialized
+ * @priority:	desired priority of the chunk
+ *
+ * Note: all locking must be provided by the caller.
+ *
+ * Before caller could add an item with certain priority, he has to
+ * initialize a priority chunk for it using this function.
+ */
+void parman_prio_init(struct parman *parman, struct parman_prio *prio,
+		      unsigned long priority)
+{
+	struct parman_prio *prio2;
+	struct list_head *pos;
+
+	INIT_LIST_HEAD(&prio->item_list);
+	prio->priority = priority;
+
+	/* Position inside the list according to priority */
+	list_for_each(pos, &parman->prio_list) {
+		prio2 = list_entry(pos, typeof(*prio2), list);
+		if (prio2->priority > prio->priority)
+			break;
+	}
+	list_add_tail(&prio->list, pos);
+}
+EXPORT_SYMBOL(parman_prio_init);
+
+/**
+ * parman_prio_fini - finalizes use of parman priority chunk
+ * @prio:	parman prio structure
+ *
+ * Note: all locking must be provided by the caller.
+ */
+void parman_prio_fini(struct parman_prio *prio)
+{
+	WARN_ON(parman_prio_used(prio));
+	list_del(&prio->list);
+}
+EXPORT_SYMBOL(parman_prio_fini);
+
+/**
+ * parman_item_add - adds a parman item under defined priority
+ * @parman:	parman instance
+ * @prio:	parman prio instance to add the item to
+ * @item:	parman item instance
+ *
+ * Note: all locking must be provided by the caller.
+ *
+ * Adds item to a array managed by parman instance under the specified priority.
+ *
+ * Returns 0 in case of success, negative number to indicate an error.
+ */
+int parman_item_add(struct parman *parman, struct parman_prio *prio,
+		    struct parman_item *item)
+{
+	return parman->algo->item_add(parman, prio, item);
+}
+EXPORT_SYMBOL(parman_item_add);
+
+/**
+ * parman_item_remove - deletes parman item
+ * @parman:	parman instance
+ * @prio:	parman prio instance to delete the item from
+ * @item:	parman item instance
+ *
+ * Note: all locking must be provided by the caller.
+ */
+void parman_item_remove(struct parman *parman, struct parman_prio *prio,
+			struct parman_item *item)
+{
+	parman->algo->item_remove(parman, prio, item);
+}
+EXPORT_SYMBOL(parman_item_remove);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Jiri Pirko <jiri@mellanox.com>");
+MODULE_DESCRIPTION("Priority-based array manager");