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

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From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [RFC][PATCH 0/5] perf/tracing/cpuhotplug: Fix locking order
Date	Fri, 12 May 2017 22:00:01 +0200
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X-Original-To	Steven Rostedt <rostedt@goodmis.org>
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On Fri, May 12, 2017 at 01:15:44PM -0400, Steven Rostedt wrote:
>  2) Allow for get_online_cpus() to nest

So Thomas and me have been avoiding doing this.

In general we avoid nested locking in the kernel. Nested locking makes
an absolute mockery of locking rules and what all gets protected.

Yes, its much easier.. But we managed to kill the BKL, so surely we can
fix the hotplug lock too, right ;-)

Thread

[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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