Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

7 files changed, 275 insertions, 0 deletions

diff --git a/Documentation/dev-tools/kunit/api/clk.rst b/Documentation/dev-tools/kunit/api/clk.rst
new file mode 100644
index 000000000..eeaa50089
--- /dev/null
+++ b/Documentation/dev-tools/kunit/api/clk.rst
@@ -0,0 +1,10 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+========
+Clk API
+========
+
+The KUnit clk API is used to test clk providers and clk consumers.
+
+.. kernel-doc:: drivers/clk/clk_kunit_helpers.c
+   :export:
diff --git a/Documentation/dev-tools/kunit/api/functionredirection.rst b/Documentation/dev-tools/kunit/api/functionredirection.rst
new file mode 100644
index 000000000..3791efc2f
--- /dev/null
+++ b/Documentation/dev-tools/kunit/api/functionredirection.rst
@@ -0,0 +1,162 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+========================
+Function Redirection API
+========================
+
+Overview
+========
+
+When writing unit tests, it's important to be able to isolate the code being
+tested from other parts of the kernel. This ensures the reliability of the test
+(it won't be affected by external factors), reduces dependencies on specific
+hardware or config options (making the test easier to run), and protects the
+stability of the rest of the system (making it less likely for test-specific
+state to interfere with the rest of the system).
+
+While for some code (typically generic data structures, helpers, and other
+"pure functions") this is trivial, for others (like device drivers,
+filesystems, core subsystems) the code is heavily coupled with other parts of
+the kernel.
+
+This coupling is often due to global state in some way: be it a global list of
+devices, the filesystem, or some hardware state. Tests need to either carefully
+manage, isolate, and restore state, or they can avoid it altogether by
+replacing access to and mutation of this state with a "fake" or "mock" variant.
+
+By refactoring access to such state, such as by introducing a layer of
+indirection which can use or emulate a separate set of test state. However,
+such refactoring comes with its own costs (and undertaking significant
+refactoring before being able to write tests is suboptimal).
+
+A simpler way to intercept and replace some of the function calls is to use
+function redirection via static stubs.
+
+
+Static Stubs
+============
+
+Static stubs are a way of redirecting calls to one function (the "real"
+function) to another function (the "replacement" function).
+
+It works by adding a macro to the "real" function which checks to see if a test
+is running, and if a replacement function is available. If so, that function is
+called in place of the original.
+
+Using static stubs is pretty straightforward:
+
+1. Add the KUNIT_STATIC_STUB_REDIRECT() macro to the start of the "real"
+   function.
+
+   This should be the first statement in the function, after any variable
+   declarations. KUNIT_STATIC_STUB_REDIRECT() takes the name of the
+   function, followed by all of the arguments passed to the real function.
+
+   For example:
+
+   .. code-block:: c
+
+	void send_data_to_hardware(const char *str)
+	{
+		KUNIT_STATIC_STUB_REDIRECT(send_data_to_hardware, str);
+		/* real implementation */
+	}
+
+2. Write one or more replacement functions.
+
+   These functions should have the same function signature as the real function.
+   In the event they need to access or modify test-specific state, they can use
+   kunit_get_current_test() to get a struct kunit pointer. This can then
+   be passed to the expectation/assertion macros, or used to look up KUnit
+   resources.
+
+   For example:
+
+   .. code-block:: c
+
+	void fake_send_data_to_hardware(const char *str)
+	{
+		struct kunit *test = kunit_get_current_test();
+		KUNIT_EXPECT_STREQ(test, str, "Hello World!");
+	}
+
+3. Activate the static stub from your test.
+
+   From within a test, the redirection can be enabled with
+   kunit_activate_static_stub(), which accepts a struct kunit pointer,
+   the real function, and the replacement function. You can call this several
+   times with different replacement functions to swap out implementations of the
+   function.
+
+   In our example, this would be
+
+   .. code-block:: c
+
+	kunit_activate_static_stub(test,
+				   send_data_to_hardware,
+				   fake_send_data_to_hardware);
+
+4. Call (perhaps indirectly) the real function.
+
+   Once the redirection is activated, any call to the real function will call
+   the replacement function instead. Such calls may be buried deep in the
+   implementation of another function, but must occur from the test's kthread.
+
+   For example:
+
+   .. code-block:: c
+
+	send_data_to_hardware("Hello World!"); /* Succeeds */
+	send_data_to_hardware("Something else"); /* Fails the test. */
+
+5. (Optionally) disable the stub.
+
+   When you no longer need it, disable the redirection (and hence resume the
+   original behaviour of the 'real' function) using
+   kunit_deactivate_static_stub(). Otherwise, it will be automatically disabled
+   when the test exits.
+
+   For example:
+
+   .. code-block:: c
+
+	kunit_deactivate_static_stub(test, send_data_to_hardware);
+
+
+It's also possible to use these replacement functions to test to see if a
+function is called at all, for example:
+
+.. code-block:: c
+
+	void send_data_to_hardware(const char *str)
+	{
+		KUNIT_STATIC_STUB_REDIRECT(send_data_to_hardware, str);
+		/* real implementation */
+	}
+
+	/* In test file */
+	int times_called = 0;
+	void fake_send_data_to_hardware(const char *str)
+	{
+		times_called++;
+	}
+	...
+	/* In the test case, redirect calls for the duration of the test */
+	kunit_activate_static_stub(test, send_data_to_hardware, fake_send_data_to_hardware);
+
+	send_data_to_hardware("hello");
+	KUNIT_EXPECT_EQ(test, times_called, 1);
+
+	/* Can also deactivate the stub early, if wanted */
+	kunit_deactivate_static_stub(test, send_data_to_hardware);
+
+	send_data_to_hardware("hello again");
+	KUNIT_EXPECT_EQ(test, times_called, 1);
+
+
+
+API Reference
+=============
+
+.. kernel-doc:: include/kunit/static_stub.h
+   :internal:
diff --git a/Documentation/dev-tools/kunit/api/index.rst b/Documentation/dev-tools/kunit/api/index.rst
new file mode 100644
index 000000000..5cdb552a0
--- /dev/null
+++ b/Documentation/dev-tools/kunit/api/index.rst
@@ -0,0 +1,48 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+API Reference
+=============
+.. toctree::
+	:hidden:
+
+	test
+	resource
+	functionredirection
+	clk
+	of
+	platformdevice
+
+
+This page documents the KUnit kernel testing API. It is divided into the
+following sections:
+
+Core KUnit API
+==============
+
+Documentation/dev-tools/kunit/api/test.rst
+
+ - Documents all of the standard testing API
+
+Documentation/dev-tools/kunit/api/resource.rst
+
+ - Documents the KUnit resource API
+
+Documentation/dev-tools/kunit/api/functionredirection.rst
+
+ - Documents the KUnit Function Redirection API
+
+Driver KUnit API
+================
+
+Documentation/dev-tools/kunit/api/clk.rst
+
+ - Documents the KUnit clk API
+
+Documentation/dev-tools/kunit/api/of.rst
+
+ - Documents the KUnit device tree (OF) API
+
+Documentation/dev-tools/kunit/api/platformdevice.rst
+
+ - Documents the KUnit platform device API
diff --git a/Documentation/dev-tools/kunit/api/of.rst b/Documentation/dev-tools/kunit/api/of.rst
new file mode 100644
index 000000000..cb4193dcd
--- /dev/null
+++ b/Documentation/dev-tools/kunit/api/of.rst
@@ -0,0 +1,13 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====================
+Device Tree (OF) API
+====================
+
+The KUnit device tree API is used to test device tree (of_*) dependent code.
+
+.. kernel-doc:: include/kunit/of.h
+   :internal:
+
+.. kernel-doc:: drivers/of/of_kunit_helpers.c
+   :export:
diff --git a/Documentation/dev-tools/kunit/api/platformdevice.rst b/Documentation/dev-tools/kunit/api/platformdevice.rst
new file mode 100644
index 000000000..49ddd5729
--- /dev/null
+++ b/Documentation/dev-tools/kunit/api/platformdevice.rst
@@ -0,0 +1,10 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===================
+Platform Device API
+===================
+
+The KUnit platform device API is used to test platform devices.
+
+.. kernel-doc:: lib/kunit/platform.c
+   :export:
diff --git a/Documentation/dev-tools/kunit/api/resource.rst b/Documentation/dev-tools/kunit/api/resource.rst
new file mode 100644
index 000000000..ec6002a6b
--- /dev/null
+++ b/Documentation/dev-tools/kunit/api/resource.rst
@@ -0,0 +1,22 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============
+Resource API
+============
+
+This file documents the KUnit resource API.
+
+Most users won't need to use this API directly, power users can use it to store
+state on a per-test basis, register custom cleanup actions, and more.
+
+.. kernel-doc:: include/kunit/resource.h
+   :internal:
+
+Managed Devices
+---------------
+
+Functions for using KUnit-managed struct device and struct device_driver.
+Include ``kunit/device.h`` to use these.
+
+.. kernel-doc:: include/kunit/device.h
+   :internal:
diff --git a/Documentation/dev-tools/kunit/api/test.rst b/Documentation/dev-tools/kunit/api/test.rst
new file mode 100644
index 000000000..c5eca423e
--- /dev/null
+++ b/Documentation/dev-tools/kunit/api/test.rst
@@ -0,0 +1,10 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+========
+Test API
+========
+
+This file documents all of the standard testing API.
+
+.. kernel-doc:: include/kunit/test.h
+   :internal: