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
  ...

1 files changed, 203 insertions, 0 deletions

diff --git a/Documentation/driver-api/media/media-committers.rst b/Documentation/driver-api/media/media-committers.rst
new file mode 100644
index 000000000..a905856f6
--- /dev/null
+++ b/Documentation/driver-api/media/media-committers.rst
@@ -0,0 +1,203 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. _Media Committers:
+
+Media Committers
+================
+
+Who is a Media Committer?
+-------------------------
+
+A Media Committer is a Media Maintainer with patchwork access who has been
+granted commit access to push patches from other developers and their own
+patches to the
+`media-committers <https://gitlab.freedesktop.org/linux-media/media-committers>`_
+tree.
+
+These commit rights are granted with expectation of responsibility:
+committers are people who care about the Linux Kernel as a whole and
+about the Linux media subsystem and want to advance its development. It
+is also based on a trust relationship among other committers, maintainers
+and the Linux Media community.
+
+As Media Committer you have the following additional responsibilities:
+
+1. Patches you authored must have a ``Signed-off-by``, ``Reviewed-by``
+   or ``Acked-by`` from another Media Maintainer;
+2. If a patch introduces a regression, then that must be corrected as soon
+   as possible. Typically the patch is either reverted, or an additional
+   patch is committed to fix the regression;
+3. If patches are fixing bugs against already released Kernels, including
+   the reverts mentioned above, the Media Committer shall add the needed
+   tags. Please see :ref:`Media development workflow` for more details.
+4. All Media Committers are responsible for maintaining
+   `Patchwork <https://patchwork.linuxtv.org/project/linux-media/list/>`_,
+   updating the state of the patches they review or merge.
+
+
+Becoming a Media Committer
+--------------------------
+
+Existing Media Committers can nominate a Media Maintainer to be granted
+commit rights. The Media Maintainer must have patchwork access,
+have been reviewing patches from third parties for some time, and has
+demonstrated a good understanding of the maintainer's duties and processes.
+
+The ultimate responsibility for accepting a nominated committer is up to
+the Media Subsystem Maintainers. The nominated committer must have earned a
+trust relationship with all Media Subsystem Maintainers, as, by granting you
+commit rights, part of their responsibilities are handed over to you.
+
+Due to that, to become a Media Committer, a consensus between all Media
+Subsystem Maintainers is required.
+
+.. Note::
+
+   In order to preserve/protect the developers that could have their commit
+   rights granted, denied or removed as well as the subsystem maintainers who
+   have the task to accept or deny commit rights, all communication related to
+   changing commit rights should happen in private as much as possible.
+
+.. _media-committer-agreement:
+
+Media Committer's agreement
+---------------------------
+
+Once a nominated committer is accepted by all Media Subsystem Maintainers,
+they will ask if the developer is interested in the nomination and discuss
+what area(s) of the media subsystem the committer will be responsible for.
+Those areas will typically be the same as the areas that the nominated
+committer is already maintaining.
+
+When the developer accepts being a committer, the new committer shall
+explicitly accept the Kernel development policies described under its
+Documentation/, and in particular to the rules in this document, by writing
+an e-mail to media-committers@linuxtv.org, with a declaration of intent
+following the model below::
+
+   I, John Doe, would like to change my status to: Committer
+
+   As Media Maintainer I accept commit rights for the following areas of
+   the media subsystem:
+
+   ...
+
+   For the purpose of committing patches to the media-committers tree,
+   I'll be using my user https://gitlab.freedesktop.org/users/<username>.
+
+Followed by a formal declaration of agreement with the Kernel development
+rules::
+
+   I agree to follow the Kernel development rules described at:
+
+   https://www.kernel.org/doc/html/latest/driver-api/media/media-committers.rst
+
+   and to the Linux Kernel development process rules.
+
+   I agree to abide by the Code of Conduct as documented in:
+   https://www.kernel.org/doc/html/latest/process/code-of-conduct.rst
+
+   I am aware that I can, at any point of time, retire. In that case, I will
+   send an e-mail to notify the Media Subsystem Maintainers for them to revoke
+   my commit rights.
+
+   I am aware that the Kernel development rules change over time.
+   By doing a new push to media-committers tree, I understand that I agree
+   to follow the rules in effect at the time of the commit.
+
+That e-mail shall be signed via the Kernel Web of trust with a PGP key cross
+signed by other Kernel and media developers. As described at
+:ref:`media-developers-gpg`, the PGP signature, together with the gitlab user
+security are fundamental components that ensure the authenticity of the merge
+requests that will happen at the media-committers.git tree.
+
+In case the kernel development process changes, by merging new commits to the
+`media-committers tree <https://gitlab.freedesktop.org/linux-media/media-committers>`_,
+the Media Committer implicitly declares their agreement with the latest
+version of the documented process including the contents of this file.
+
+If a Media Committer decides to retire, it is the committer's duty to
+notify the Media Subsystem Maintainers about that decision.
+
+.. note::
+
+   1. Changes to the kernel media development process shall be announced in
+      the media-committers mailing list with a reasonable review period. All
+      committers are automatically subscribed to that mailing list;
+   2. Due to the distributed nature of the Kernel development, it is
+      possible that kernel development process changes may end being
+      reviewed/merged at the Linux Docs and/or at the Linux Kernel mailing
+      lists, especially for the contents under Documentation/process and for
+      trivial typo fixes.
+
+Media Core Committers
+---------------------
+
+A Media Core Committer is a Media Core Maintainer with commit rights.
+
+As described in Documentation/driver-api/media/maintainer-entry-profile.rst,
+a Media Core Maintainer maintains media core frameworks as well, besides
+just drivers, and so is allowed to change core files and the media subsystem's
+Kernel API. The extent of the core committer's grants will be detailed by the
+Media Subsystem Maintainers when they nominate a Media Core Committer.
+
+Existing Media Committers may become Media Core Committers and vice versa.
+Such decisions will be taken in consensus among the Media Subsystem
+Maintainers.
+
+Media committers rules
+----------------------
+
+Media committers shall do their best efforts to avoid merging patches that
+would break any existing drivers. If it breaks, fixup or revert patches
+shall be merged as soon as possible, aiming to be merged at the same Kernel
+cycle the bug is reported.
+
+Media committers shall behave accordingly to the rights granted by
+the Media Subsystem Maintainers, especially with regards of the scope of changes
+they may apply directly at the media-committers tree. That scope can
+change over time on a mutual agreement between Media Committers and
+Media Subsystem Maintainers.
+
+The Media Committer workflow is described at :ref:`Media development workflow`.
+
+.. _Maintain Media Status:
+
+Maintaining Media Maintainer or Committer status
+------------------------------------------------
+
+A community of maintainers working together to move the Linux Kernel
+forward is essential to creating successful projects that are rewarding
+to work on. If there are problems or disagreements within the community,
+they can usually be solved through healthy discussion and debate.
+
+In the unhappy event that a Media Maintainer or Committer continues to
+disregard good citizenship (or actively disrupts the project), we may need
+to revoke that person's status. In such cases, if someone suggests the
+revocation with a good reason, then after discussing this among the Media
+Maintainers, the final decision is taken by the Media Subsystem Maintainers.
+
+As the decision to become a Media Maintainer or Committer comes from a
+consensus between Media Subsystem Maintainers, a single Media Subsystem
+Maintainer not trusting the Media Maintainer or Committer anymore is enough
+to revoke their maintenance, Patchwork grants and/or commit rights.
+
+Having commit rights revoked doesn't prevent Media Maintainers to keep
+contributing to the subsystem either via the pull request or via email workflow
+as documented at the :ref:`Media development workflow`.
+
+If a maintainer is inactive for more than a couple of Kernel cycles,
+maintainers will try to reach you via e-mail. If not possible, they may
+revoke their maintainer/patchwork and committer rights and update MAINTAINERS
+file entries accordingly. If you wish to resume contributing as maintainer
+later on, then contact the Media Subsystem Maintainers to ask if your
+maintenance, Patchwork grants and commit rights can be restored.
+
+References
+----------
+
+Much of this was inspired by/copied from the committer policies of:
+
+- `Chromium <https://chromium.googlesource.com/chromium/src/+/main/docs/contributing.md>`_;
+- `WebKit <https://webkit.org/commit-and-review-policy/>`_;
+- `Mozilla <https://www.mozilla.org/hacking/committer/>`_.