linux-kernel - Re: [PATCH 4/6] uprobes/tracing: Introduce is_trace_uprobe

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Date:	Mon, 4 Feb 2013 21:42:27 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>,
	Anton Arapov <anton@...hat.com>,
	Frank Eigler <fche@...hat.com>,
	Josh Stone <jistone@...hat.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	"Suzuki K. Poulose" <suzuki@...ibm.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] uprobes/tracing: Introduce
 is_trace_uprobe_enabled()

* Oleg Nesterov <oleg@...hat.com> [2013-01-31 20:18:25]:

> probe_event_enable/disable() check tu->consumer != NULL to avoid the
> wrong uprobe_register/unregister().
> 
> We are going to kill this pointer and "struct uprobe_trace_consumer",
> so we add the new helper, is_trace_uprobe_enabled(), which can rely
> on TP_FLAG_TRACE/TP_FLAG_PROFILE instead.
> 
> Note: the current logic doesn't look optimal, it is not clear why
> TP_FLAG_TRACE/TP_FLAG_PROFILE are mutually exclusive, we will probably
> change this later.
> 
> Also kill the unused TP_FLAG_UPROBE.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>


Acked-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>

> ---
>  kernel/trace/trace_probe.h  |    1 -
>  kernel/trace/trace_uprobe.c |    9 +++++++--
>  2 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 9337086..5c7e09d 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -66,7 +66,6 @@
>  #define TP_FLAG_TRACE		1
>  #define TP_FLAG_PROFILE		2
>  #define TP_FLAG_REGISTERED	4
> -#define TP_FLAG_UPROBE		8
> 
> 
>  /* data_rloc: data relative location, compatible with u32 */
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index f02bbec..947379a 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -536,12 +536,17 @@ partial:
>  	return TRACE_TYPE_PARTIAL_LINE;
>  }
> 
> +static inline bool is_trace_uprobe_enabled(struct trace_uprobe *tu)
> +{
> +	return tu->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE);
> +}
> +
>  static int probe_event_enable(struct trace_uprobe *tu, int flag)
>  {
>  	struct uprobe_trace_consumer *utc;
>  	int ret = 0;
> 
> -	if (tu->consumer)
> +	if (is_trace_uprobe_enabled(tu))
>  		return -EINTR;
> 
>  	utc = kzalloc(sizeof(struct uprobe_trace_consumer), GFP_KERNEL);
> @@ -565,7 +570,7 @@ static int probe_event_enable(struct trace_uprobe *tu, int flag)
> 
>  static void probe_event_disable(struct trace_uprobe *tu, int flag)
>  {
> -	if (!tu->consumer)
> +	if (!is_trace_uprobe_enabled(tu))
>  		return;
> 
>  	uprobe_unregister(tu->inode, tu->offset, &tu->consumer->cons);
> -- 
> 1.5.5.1
> 

-- 
Thanks and Regards
Srikar Dronamraju

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