linux-kernel - Re: [RFC PATCH 1/3] perf probe: Init symbol as kprobe if any pev is kprobe

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Date:	Sat, 27 Jun 2015 15:34:38 +0800
From:	"Wangnan (F)" <wangnan0@...wei.com>
To:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	<acme@...nel.org>, <ast@...mgrid.com>, <brendan.d.gregg@...il.com>,
	<daniel@...earbox.net>, <namhyung@...nel.org>, <paulus@...ba.org>,
	<a.p.zijlstra@...llo.nl>, <mingo@...hat.com>, <jolsa@...nel.org>,
	<dsahern@...il.com>
CC:	<linux-kernel@...r.kernel.org>, <lizefan@...wei.com>,
	<hekuang@...wei.com>, <xiakaixu@...wei.com>, <pi3orama@....com>
Subject: Re: [RFC PATCH 1/3] perf probe: Init symbol as kprobe if any pev
 is kprobe



On 2015/6/27 15:29, Masami Hiramatsu wrote:
> On 2015/06/25 19:37, Wang Nan wrote:
>> Before this patch, add_perf_probe_events() init symbol maps only for
>> uprobe if the first pev passed to it is a uprobe event. However, with
>> the incoming BPF uprobe support, now it will be possible to pass an
>> array with combined kprobe and uprobe events to add_perf_probe_events().
> This description is not correct. Actually, add_perf_probe_events already
> supports mix of uprobes and kprobes. However, from the command line syntax
> constrains the first elements of the probe_event arrays must be kprobes.
> So, if the array starts with uprobes, no kprobes should be there.
>
>> This patch check all pevs instead of the first one, and init kernel
>> symbol if any events is not uprobe.
> Anyway, I prefer to call init_symbol_maps() with "false" :)

I also prefer "false", so I try to find whether all events are uprobe 
instead
of init_symbol_maps(true).

So for this patch only commit message needs to be corrected, the code is
no problem, right?

Thank you.

> Thank you,
>
>> Signed-off-by: Wang Nan <wangnan0@...wei.com>
>> ---
>>   tools/perf/util/probe-event.c | 15 ++++++++++++++-
>>   1 file changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
>> index b386d2f..a2b3026 100644
>> --- a/tools/perf/util/probe-event.c
>> +++ b/tools/perf/util/probe-event.c
>> @@ -2802,8 +2802,21 @@ int cleanup_perf_probe_event(struct perf_probe_event *pev)
>>   int add_perf_probe_events(struct perf_probe_event *pevs, int npevs, bool cleanup)
>>   {
>>   	int i, ret;
>> +	bool user_only = true;
>>   
>> -	ret = init_symbol_maps(pevs->uprobes);
>> +	/* If any pev is kprobe, init kernel symbols. */
>> +	for (i = 0; i < npevs; i++) {
>> +		if (!pevs[i].uprobes) {
>> +			user_only = false;
>> +			break;
>> +		}
>> +	}
>> +
>> +	/*
>> +	 * Compiler can drop user_only:
>> +	 *  ret = init_symbol_maps(i >= npevs);
>> +	 */
>> +	ret = init_symbol_maps(user_only);
>>   	if (ret < 0)
>>   		return ret;
>>   
>>
>


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