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, 189 insertions, 0 deletions

diff --git a/include/drm/drm_exec.h b/include/drm/drm_exec.h
new file mode 100644
index 000000000..cc2937185
--- /dev/null
+++ b/include/drm/drm_exec.h
@@ -0,0 +1,189 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+
+#ifndef __DRM_EXEC_H__
+#define __DRM_EXEC_H__
+
+#include <linux/compiler.h>
+#include <linux/ww_mutex.h>
+
+#define DRM_EXEC_INTERRUPTIBLE_WAIT	BIT(0)
+#define DRM_EXEC_IGNORE_DUPLICATES	BIT(1)
+
+/*
+ * Dummy value used to initially enter the retry loop.
+ * internal use only.
+ */
+#define DRM_EXEC_DUMMY ((void *)~0)
+
+struct drm_gem_object;
+
+/**
+ * struct drm_exec - Execution context
+ */
+struct drm_exec {
+	/**
+	 * @flags: Flags to control locking behavior
+	 */
+	u32                     flags;
+
+	/**
+	 * @ticket: WW ticket used for acquiring locks
+	 */
+	struct ww_acquire_ctx	ticket;
+
+	/**
+	 * @num_objects: number of objects locked
+	 */
+	unsigned int		num_objects;
+
+	/**
+	 * @max_objects: maximum objects in array
+	 */
+	unsigned int		max_objects;
+
+	/**
+	 * @objects: array of the locked objects
+	 */
+	struct drm_gem_object	**objects;
+
+	/**
+	 * @contended: contended GEM object we backed off for
+	 */
+	struct drm_gem_object	*contended;
+
+	/**
+	 * @prelocked: already locked GEM object due to contention
+	 */
+	struct drm_gem_object *prelocked;
+};
+
+/**
+ * drm_exec_obj() - Return the object for a give drm_exec index
+ * @exec: Pointer to the drm_exec context
+ * @index: The index.
+ *
+ * Return: Pointer to the locked object corresponding to @index if
+ * index is within the number of locked objects. NULL otherwise.
+ */
+static inline struct drm_gem_object *
+drm_exec_obj(struct drm_exec *exec, unsigned long index)
+{
+	return index < exec->num_objects ? exec->objects[index] : NULL;
+}
+
+/* Helper for drm_exec_for_each_locked_object(). Internal use only. */
+#define __drm_exec_for_each_locked_object(exec, obj, __index)		\
+	for (unsigned long __index = 0; ((obj) = drm_exec_obj(exec, __index)); ++__index)
+/**
+ * drm_exec_for_each_locked_object - iterate over all the locked objects
+ * @exec: drm_exec object
+ * @obj: the current GEM object
+ *
+ * Iterate over all the locked GEM objects inside the drm_exec object.
+ */
+#define drm_exec_for_each_locked_object(exec, obj)			\
+	__drm_exec_for_each_locked_object(exec, obj, __UNIQUE_ID(drm_exec))
+
+/* Helper for drm_exec_for_each_locked_object_reverse(). Internal use only. */
+#define __drm_exec_for_each_locked_object_reverse(exec, obj, __index)	\
+	for (unsigned long __index = (exec)->num_objects - 1;		\
+	     ((obj) = drm_exec_obj(exec, __index)); --__index)
+/**
+ * drm_exec_for_each_locked_object_reverse - iterate over all the locked
+ * objects in reverse locking order
+ * @exec: drm_exec object
+ * @obj: the current GEM object
+ *
+ * Iterate over all the locked GEM objects inside the drm_exec object in
+ * reverse locking order. Note that the internal index may wrap around,
+ * but that will be caught by drm_exec_obj(), returning a NULL object.
+ */
+#define drm_exec_for_each_locked_object_reverse(exec, obj)		\
+	__drm_exec_for_each_locked_object_reverse(exec, obj, __UNIQUE_ID(drm_exec))
+
+/**
+ * drm_exec_until_all_locked - loop until all GEM objects are locked
+ * @exec: drm_exec object
+ *
+ * Core functionality of the drm_exec object. Loops until all GEM objects are
+ * locked and no more contention exists. At the beginning of the loop it is
+ * guaranteed that no GEM object is locked.
+ *
+ * A global label name drm_exec_retry is used, if you need to use more than one
+ * instance of this macro in the same function the label needs to be made local
+ * to the block with the __label__ keyword.
+ */
+#define drm_exec_until_all_locked(exec)					\
+	for (bool const __maybe_unused __drm_exec_loop = false;		\
+	     drm_exec_cleanup(exec);)					\
+		if (false) {						\
+drm_exec_retry: __maybe_unused;						\
+			continue;					\
+		} else
+
+/**
+ * drm_exec_retry_on_contention - restart the loop to grap all locks
+ * @exec: drm_exec object
+ *
+ * Control flow helper to continue when a contention was detected and we need to
+ * clean up and re-start the loop to prepare all GEM objects.
+ * The __drm_exec_loop check exists to prevent usage outside of an
+ * drm_exec_until_all_locked() loop.
+ */
+#define drm_exec_retry_on_contention(exec)			\
+	do {							\
+		if (unlikely(drm_exec_is_contended(exec)))	\
+			goto drm_exec_retry;			\
+	} while (__drm_exec_loop)
+
+/**
+ * drm_exec_is_contended - check for contention
+ * @exec: drm_exec object
+ *
+ * Returns true if the drm_exec object has run into some contention while
+ * locking a GEM object and needs to clean up.
+ */
+static inline bool drm_exec_is_contended(struct drm_exec *exec)
+{
+	return !!exec->contended;
+}
+
+/**
+ * drm_exec_retry() - Unconditionally restart the loop to grab all locks.
+ * @exec: drm_exec object
+ *
+ * Unconditionally retry the loop to lock all objects. For consistency,
+ * the exec object needs to be newly initialized.
+ * The __drm_exec_loop check exists to prevent usage outside of an
+ * drm_exec_until_all_locked() loop.
+ */
+#define drm_exec_retry(_exec)					\
+	do {							\
+		WARN_ON((_exec)->contended != DRM_EXEC_DUMMY);	\
+		goto drm_exec_retry;				\
+	} while (__drm_exec_loop)
+
+/**
+ * drm_exec_ticket - return the ww_acquire_ctx for this exec context
+ * @exec: drm_exec object
+ *
+ * Return: Pointer to the ww_acquire_ctx embedded in @exec.
+ */
+static inline struct ww_acquire_ctx *drm_exec_ticket(struct drm_exec *exec)
+{
+	return &exec->ticket;
+}
+
+void drm_exec_init(struct drm_exec *exec, u32 flags, unsigned nr);
+void drm_exec_fini(struct drm_exec *exec);
+bool drm_exec_cleanup(struct drm_exec *exec);
+int drm_exec_lock_obj(struct drm_exec *exec, struct drm_gem_object *obj);
+void drm_exec_unlock_obj(struct drm_exec *exec, struct drm_gem_object *obj);
+int drm_exec_prepare_obj(struct drm_exec *exec, struct drm_gem_object *obj,
+			 unsigned int num_fences);
+int drm_exec_prepare_array(struct drm_exec *exec,
+			   struct drm_gem_object **objects,
+			   unsigned int num_objects,
+			   unsigned int num_fences);
+
+#endif