linux-kernel - Re: [PATCH 02/11] [BUGFIX] ftrace, kprobes: Fix a deadlock on ftrace_regex

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Date:	Thu, 09 May 2013 12:27:40 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc:	linux-kernel@...r.kernel.org,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	yrl.pp-manager.tt@...achi.com, Oleg Nesterov <oleg@...hat.com>,
	Ingo Molnar <mingo@...hat.com>,
	Tom Zanussi <tom.zanussi@...el.com>
Subject: Re: [PATCH 02/11] [BUGFIX] ftrace, kprobes: Fix a deadlock on
 ftrace_regex_lock

On Thu, 2013-05-09 at 14:44 +0900, Masami Hiramatsu wrote:

> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 8a5c017..3f29b3d 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -64,9 +64,17 @@
>  
>  #define FL_GLOBAL_CONTROL_MASK (FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_CONTROL)
>  
> +#ifdef CONFIG_DYNAMIC_FTRACE
> +#define INIT_REGEX_LOCK(opsname)	\
> +	.regex_lock	= __MUTEX_INITIALIZER(opsname.regex_lock),
> +#else
> +#define INIT_REGEX_LOCK(opsname)
> +#endif
> +
>  static struct ftrace_ops ftrace_list_end __read_mostly = {
>  	.func		= ftrace_stub,
>  	.flags		= FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_STUB,
> +	INIT_REGEX_LOCK(ftrace_list_end)
>  };
>  

We probably should have a better way to initialize this. As there are 26
ftrace_ops currently in the kernel (and this patch doesn't cover all of
them). Maybe have the first time its registered to initialize it.

I think adding the INIT_REGEX_LOCK() all over the place is rather ugly.

-- Steve


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