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, 152 insertions, 0 deletions

diff --git a/drivers/md/dm-vdo/completion.h b/drivers/md/dm-vdo/completion.h
new file mode 100644
index 000000000..3407f34ce
--- /dev/null
+++ b/drivers/md/dm-vdo/completion.h
@@ -0,0 +1,152 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef VDO_COMPLETION_H
+#define VDO_COMPLETION_H
+
+#include "permassert.h"
+
+#include "status-codes.h"
+#include "types.h"
+
+/**
+ * vdo_run_completion() - Run a completion's callback or error handler on the current thread.
+ *
+ * Context: This function must be called from the correct callback thread.
+ */
+static inline void vdo_run_completion(struct vdo_completion *completion)
+{
+	if ((completion->result != VDO_SUCCESS) && (completion->error_handler != NULL)) {
+		completion->error_handler(completion);
+		return;
+	}
+
+	completion->callback(completion);
+}
+
+void vdo_set_completion_result(struct vdo_completion *completion, int result);
+
+void vdo_initialize_completion(struct vdo_completion *completion, struct vdo *vdo,
+			       enum vdo_completion_type type);
+
+/**
+ * vdo_reset_completion() - Reset a completion to a clean state, while keeping the type, vdo and
+ *                          parent information.
+ */
+static inline void vdo_reset_completion(struct vdo_completion *completion)
+{
+	completion->result = VDO_SUCCESS;
+	completion->complete = false;
+}
+
+void vdo_launch_completion_with_priority(struct vdo_completion *completion,
+					 enum vdo_completion_priority priority);
+
+/**
+ * vdo_launch_completion() - Launch a completion with default priority.
+ */
+static inline void vdo_launch_completion(struct vdo_completion *completion)
+{
+	vdo_launch_completion_with_priority(completion, VDO_WORK_Q_DEFAULT_PRIORITY);
+}
+
+/**
+ * vdo_continue_completion() - Continue processing a completion.
+ * @result: The current result (will not mask older errors).
+ *
+ * Continue processing a completion by setting the current result and calling
+ * vdo_launch_completion().
+ */
+static inline void vdo_continue_completion(struct vdo_completion *completion, int result)
+{
+	vdo_set_completion_result(completion, result);
+	vdo_launch_completion(completion);
+}
+
+void vdo_finish_completion(struct vdo_completion *completion);
+
+/**
+ * vdo_fail_completion() - Set the result of a completion if it does not already have an error,
+ *                         then finish it.
+ */
+static inline void vdo_fail_completion(struct vdo_completion *completion, int result)
+{
+	vdo_set_completion_result(completion, result);
+	vdo_finish_completion(completion);
+}
+
+/**
+ * vdo_assert_completion_type() - Assert that a completion is of the correct type.
+ *
+ * Return: VDO_SUCCESS or an error
+ */
+static inline int vdo_assert_completion_type(struct vdo_completion *completion,
+					     enum vdo_completion_type expected)
+{
+	return VDO_ASSERT(expected == completion->type,
+			  "completion type should be %u, not %u", expected,
+			  completion->type);
+}
+
+static inline void vdo_set_completion_callback(struct vdo_completion *completion,
+					       vdo_action_fn callback,
+					       thread_id_t callback_thread_id)
+{
+	completion->callback = callback;
+	completion->callback_thread_id = callback_thread_id;
+}
+
+/**
+ * vdo_launch_completion_callback() - Set the callback for a completion and launch it immediately.
+ */
+static inline void vdo_launch_completion_callback(struct vdo_completion *completion,
+						  vdo_action_fn callback,
+						  thread_id_t callback_thread_id)
+{
+	vdo_set_completion_callback(completion, callback, callback_thread_id);
+	vdo_launch_completion(completion);
+}
+
+/**
+ * vdo_prepare_completion() - Prepare a completion for launch.
+ *
+ * Resets the completion, and then sets its callback, error handler, callback thread, and parent.
+ */
+static inline void vdo_prepare_completion(struct vdo_completion *completion,
+					  vdo_action_fn callback,
+					  vdo_action_fn error_handler,
+					  thread_id_t callback_thread_id, void *parent)
+{
+	vdo_reset_completion(completion);
+	vdo_set_completion_callback(completion, callback, callback_thread_id);
+	completion->error_handler = error_handler;
+	completion->parent = parent;
+}
+
+/**
+ * vdo_prepare_completion_for_requeue() - Prepare a completion for launch ensuring that it will
+ *                                        always be requeued.
+ *
+ * Resets the completion, and then sets its callback, error handler, callback thread, and parent.
+ */
+static inline void vdo_prepare_completion_for_requeue(struct vdo_completion *completion,
+						      vdo_action_fn callback,
+						      vdo_action_fn error_handler,
+						      thread_id_t callback_thread_id,
+						      void *parent)
+{
+	vdo_prepare_completion(completion, callback, error_handler,
+			       callback_thread_id, parent);
+	completion->requeue = true;
+}
+
+void vdo_enqueue_completion(struct vdo_completion *completion,
+			    enum vdo_completion_priority priority);
+
+
+bool vdo_requeue_completion_if_needed(struct vdo_completion *completion,
+				      thread_id_t callback_thread_id);
+
+#endif /* VDO_COMPLETION_H */