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Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order

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On Fri, May 12, 2017 at 05:34:48PM -0400, Steven Rostedt wrote:
> On Fri, 12 May 2017 21:49:56 +0200

[ . . . ]

> This means that text_mutex, which was taken by the alternative code, no
> longer is taken in cpu hotplug code. That means there's no longer a
> deadlock scenario, as we don't have anyplace(*) that grabs
> get_online_cpus() and takes the text_mutex. Removing that will
> simplify things tremendously!
> 
> (*) with one exception: perf.
> 
> Currently perf does a get_online_cpu() at a high level. Will it be
> possible to move that down, such that we don't have it taken when we do
> any software events?

Can perf get rid of get_online_cpus(), perhaps using the mutexes acquired
by perf_event_init_cpu() or by perf_event_exit_cpu()?

							Thanx, Paul

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[RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order Steven Rostedt <rostedt@goodmis.org> - 2017-05-12 19:30 +0200
  [RFC][PATCH 5/5] perf: Grab event_mutex before taking get_online_cpus() Steven Rostedt <rostedt@goodmis.org> - 2017-05-12 19:30 +0200
  [RFC][PATCH 3/5] kprobes: Take get_online_cpus() before taking jump_label_lock() Steven Rostedt <rostedt@goodmis.org> - 2017-05-12 19:30 +0200
    Re: [RFC][PATCH 3/5] kprobes: Take get_online_cpus() before taking  jump_label_lock() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-05-12 20:40 +0200
      Re: [RFC][PATCH 3/5] kprobes: Take get_online_cpus() before taking  jump_label_lock() Steven Rostedt <rostedt@goodmis.org> - 2017-05-12 20:50 +0200
    Re: [RFC][PATCH 3/5] kprobes: Take get_online_cpus() before taking  jump_label_lock() Masami Hiramatsu <mhiramat@kernel.org> - 2017-05-17 20:00 +0200
  Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-05-12 20:20 +0200
  Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order Peter Zijlstra <peterz@infradead.org> - 2017-05-12 22:00 +0200
    Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order Steven Rostedt <rostedt@goodmis.org> - 2017-05-12 22:20 +0200
    Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order Steven Rostedt <rostedt@goodmis.org> - 2017-05-12 23:40 +0200
      Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-05-13 15:50 +0200
        Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order Peter Zijlstra <peterz@infradead.org> - 2017-05-15 11:10 +0200
          Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-05-15 20:50 +0200
            Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order Peter Zijlstra <peterz@infradead.org> - 2017-05-16 10:20 +0200
              Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-05-16 14:50 +0200
                Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-05-16 16:30 +0200
                Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order Peter Zijlstra <peterz@infradead.org> - 2017-05-17 12:50 +0200
                Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-05-17 17:00 +0200
                Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-05-18 06:00 +0200
    Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order Steven Rostedt <rostedt@goodmis.org> - 2017-05-15 21:10 +0200

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