linux-kernel - [PATCH 0/7] perf: Untangle aux refcounting

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Message-Id: <1449138762-15194-1-git-send-email-alexander.shishkin@linux.intel.com>
Date:	Thu,  3 Dec 2015 12:32:35 +0200
From:	Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
	vince@...ter.net, eranian@...gle.com, johannes@...solutions.net,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Subject: [PATCH 0/7] perf: Untangle aux refcounting

Hi Peter,

As we discussed, here's a patchset that tweaks aux refcounting so that
freeing stuff in NMI context is no longer possible. Also, as
discussed, I tried to generalize the unlock context -
task_function_call - lock context - check stuff - repeat sequence into
a helper and converted the existing offenders to use that instead.

I'm not very happy with the way perf_mmap_close turned out, but I
figured it's an unmap path and it's at least a start. At some point, a
better way of doing things to events on rb::event_list may have to be
devised.

For bisectability purposes, it *may* make sense to bring the last two
patches forward as they should work just fine with or without the
perf_event_stop() trick in mmap_close.

I may have gone slightly over the top with the verbal explanations
around what's happening, but at least we won't have to dig up old irc
conversations next time it blows up (which it won't do).

Alexander Shishkin (7):
  perf: Refuse to begin aux transaction after aux_mmap_count drops
  perf: Generalize task_function_call()ers
  perf: Add a helper to stop running events
  perf: Free aux pages in unmap path
  perf: Document aux api usage
  perf/x86/intel/pt: Move transaction start/stop to pmu start/stop
    callbacks
  perf/x86/intel/bts: Move transaction start/stop to start/stop
    callbacks

 arch/x86/kernel/cpu/perf_event_intel_bts.c | 105 +++++------
 arch/x86/kernel/cpu/perf_event_intel_pt.c  |  85 +++------
 include/linux/perf_event.h                 |   1 +
 kernel/events/core.c                       | 287 ++++++++++++++++-------------
 kernel/events/internal.h                   |   1 -
 kernel/events/ring_buffer.c                |  52 +++---
 6 files changed, 262 insertions(+), 269 deletions(-)

-- 
2.6.2

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