Re: [PATCH] x86: avoid calling arch_trigger_all_cpu_backtrace() atthe same time on SMP

[Ingo Molnar]

* Dongdong Deng <dongdong.deng@xxxxxxxxxxxxx> wrote:

> +static int backtrace_flag;

> +	if (cmpxchg(&backtrace_flag, 0, 1) != 0)

Sorry to be a PITA, but i asked for test_and_set() because that's the simplest 
primitive. cmpxchg() semantics is not nearly as obvious and people regularly get it 
wrong :-/

Also, variables that cmpxchg or test_and_set operates on need to be long, not int.

	Ingo
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