linux.git/kernel/events, branch v4.5-rc2

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-01-31T23:38:27+00:00

Pull perf fixes from Thomas Gleixner:
 "This is much bigger than typical fixes, but Peter found a category of
  races that spurred more fixes and more debugging enhancements.  Work
  started before the merge window, but got finished only now.

  Aside of that this contains the usual small fixes to perf and tools.
  Nothing particular exciting"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (43 commits)
  perf: Remove/simplify lockdep annotation
  perf: Synchronously clean up child events
  perf: Untangle 'owner' confusion
  perf: Add flags argument to perf_remove_from_context()
  perf: Clean up sync_child_event()
  perf: Robustify event->owner usage and SMP ordering
  perf: Fix STATE_EXIT usage
  perf: Update locking order
  perf: Remove __free_event()
  perf/bpf: Convert perf_event_array to use struct file
  perf: Fix NULL deref
  perf/x86: De-obfuscate code
  perf/x86: Fix uninitialized value usage
  perf: Fix race in perf_event_exit_task_context()
  perf: Fix orphan hole
  perf stat: Do not clean event's private stats
  perf hists: Fix HISTC_MEM_DCACHELINE width setting
  perf annotate browser: Fix behaviour of Shift-Tab with nothing focussed
  perf tests: Remove wrong semicolon in while loop in CQM test
  perf: Synchronously free aux pages in case of allocation failure
  ...

perf: Remove/simplify lockdep annotation

2016-01-29T07:35:36+00:00

Now that the perf_event_ctx_lock_nested() call has moved from
put_event() into perf_event_release_kernel() the first reason is no
longer valid as that can no longer happen.

The second reason seems to have been invalidated when Al Viro made fput()
unconditionally async in the following commit:

  4a9d4b024a31 ("switch fput to task_work_add")

such that munmap()->fput()->release()->perf_release() would no longer happen.

Therefore, remove the annotation. This should increase the efficiency
of lockdep coverage of perf locking.

Suggested-by: Alexander Shishkin 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Signed-off-by: Ingo Molnar

perf: Synchronously clean up child events

2016-01-29T07:35:35+00:00

The orphan cleanup workqueue doesn't always catch orphans, for example,
if they never schedule after they are orphaned. IOW, the event leak is
still very real. It also wouldn't work for kernel counters.

Doing it synchonously is a little hairy due to lock inversion issues,
but is made to work.

Patch based on work by Alexander Shishkin.

Suggested-by: Alexander Shishkin 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Cc: vince@deater.net
Signed-off-by: Ingo Molnar

perf: Untangle 'owner' confusion

2016-01-29T07:35:34+00:00

There are two concepts of owner wrt an event and they are conflated:

 - event::owner / event::owner_list,
   used by prctl(.option = PR_TASK_PERF_EVENTS_{EN,DIS}ABLE).

 - the 'owner' of the event object, typically the file descriptor.

Currently these two concepts are conflated, which gives trouble with
scm_rights passing of file descriptors. Passing the event and then
closing the creating task would render the event 'orphan' and would
have it cleared out. Unlikely what is expectd.

This patch untangles these two concepts by using PERF_EVENT_STATE_EXIT
to denote the second type.

Reported-by: Alexei Starovoitov 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Signed-off-by: Ingo Molnar

perf: Add flags argument to perf_remove_from_context()

2016-01-29T07:35:33+00:00

In preparation to adding more options, convert the boolean argument
into a flags word.

Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Signed-off-by: Ingo Molnar

perf: Clean up sync_child_event()

2016-01-29T07:35:32+00:00

sync_child_event() has outgrown its purpose, it does far too much.
Bring it back to its named purpose.

Rename __perf_event_exit_task() to perf_event_exit_event() to better
reflect what it does and move the event->state assignment under the
ctx->lock, like state changes ought to be.

Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Signed-off-by: Ingo Molnar

perf: Robustify event->owner usage and SMP ordering

2016-01-29T07:35:31+00:00

Use smp_store_release() to clear event->owner and
lockless_dereference() to observe it. Further use READ_ONCE() for all
lockless reads.

This changes perf_remove_from_owner() to leave event->owner cleared.

Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Signed-off-by: Ingo Molnar

perf: Fix STATE_EXIT usage

2016-01-29T07:35:30+00:00

We should never attempt to enable a STATE_EXIT event.

Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Signed-off-by: Ingo Molnar

perf: Update locking order

2016-01-29T07:35:29+00:00

Update the locking order to note that ctx::lock nests inside of
child_mutex, as per:

  perf_ioctl():                ctx::mutex
  -> perf_event_for_each():    event::child_mutex
    -> _perf_event_enable():   ctx::lock

Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Signed-off-by: Ingo Molnar

perf: Remove __free_event()

2016-01-29T07:35:25+00:00

There is but a single caller, remove the function - we already have
_free_event(), the extra indirection is nonsensical..

Signed-off-by: Peter Zijlstra (Intel) 
Cc: Arnaldo Carvalho de Melo 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: Vince Weaver 
Signed-off-by: Ingo Molnar