• Peter Zijlstra's avatar
    perf/core: Fix another perf,trace,cpuhp lock inversion · 43fa87f7
    Peter Zijlstra authored
    
    
    Lockdep noticed the following 3-way lockup race:
    
            perf_trace_init()
     #0       mutex_lock(&event_mutex)
              perf_trace_event_init()
                perf_trace_event_reg()
                  tp_event->class->reg() := tracepoint_probe_register
     #1              mutex_lock(&tracepoints_mutex)
                      trace_point_add_func()
     #2                  static_key_enable()
    
     #2	do_cpu_up()
    	  perf_event_init_cpu()
     #3	    mutex_lock(&pmus_lock)
     #4	    mutex_lock(&ctx->mutex)
    
    	perf_ioctl()
     #4	  ctx = perf_event_ctx_lock()
    	  _perf_iotcl()
    	    ftrace_profile_set_filter()
     #0	      mutex_lock(&event_mutex)
    
    Fudge it for now by noting that the tracepoint state does not depend
    on the event <-> context relation. Ugly though :/
    Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    43fa87f7
core.c 266 KB