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Date: Wed, 7 Jan 2015 18:34:00 +0800
From: Wang Nan <wangnan0@huawei.com>
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To: Hillf Danton <hillf.zj@alibaba-inc.com>
CC: <linux@arm.linux.org.uk>, "'Ingo Molnar'" <mingo@redhat.com>,
        <masami.hiramatsu.pt@hitachi.com>, <anil.s.keshavamurthy@intel.com>,
        <davem@davemloft.net>, <ananth@in.ibm.com>, <dave.long@linaro.org>,
        <tixy@linaro.org>, <lizefan@huawei.com>,
        "'linux-kernel'" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 09/11] kprobes: core logic of eraly kprobes
References: <043a01d02a5b$44ec45f0$cec4d1d0$@alibaba-inc.com> <54ACFFB6.3040102@huawei.com> <045301d02a60$ff36e8c0$fda4ba40$@alibaba-inc.com>
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On 2015/1/7 18:02, Hillf Danton wrote:
>>>>
>>>> +struct early_kprobe_slot {
>>>> +	struct optimized_kprobe op;
>>>> +};
>>>> +
>>> [...]
>>>>
>>>>  /* Free optimized instructions and optimized_kprobe */
>>>> +static int ek_free_early_kprobe(struct early_kprobe_slot *slot);
>>>
>>> [2] How is it implemented? In subsequent patches?
>>>
>>
>> It is implemented using macro. Please see patch 7/11 and
>>
>> DEFINE_EKPROBE_ALLOC_OPS(struct early_kprobe_slot, early_kprobe, static);
>>
> What is the reason that it is listed in C file, given that it is done in H already?
> 

This macro defines an array and a bitmap, not only declare them. In addition,
the functions defined by it are used only in this specific .c file.

If there are not only one .c files use it, I think patch 7 can be improved:

#define DEFINE_EKPROBE_AREA(__t, __static)				\
__static __t __ek_##__name##_slots[NR_EARLY_KPROBES_SLOTS];		\
__static unsigned long __ek_##__name##_bitmap[EARLY_KPROBES_BITMAP_SZ];

#define DEFINE_EKPROBE_ALLOC_OPS(__t, __name, __static)			\
DEFINE_EKPROBE_AREA(__t, __static)					\
__DEFINE_EKPROBE_ALLOC_OPS(__t, __name)					\
static inline __t *ek_alloc_##__name(void)				\
{									\
...

In .h file(s):
DEFINE_EKPROBE_ALLOC_OPS(struct early_kprobe_slot, early_kprobe, extern)

In .c file:
DEFINE_EKPROBE_AREA(__t, )

What do you think?