linux-kernel - Re: [PATCH v2] arch/x86/tools/gen-insn-attr-x86.awk: remove duplicate const

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Date:	Mon, 10 Dec 2012 10:27:51 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Cong Ding <dinggnu@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org,
	"yrl.pp-manager.tt@...achi.com" <yrl.pp-manager.tt@...achi.com>
Subject: Re: [PATCH v2] arch/x86/tools/gen-insn-attr-x86.awk: remove duplicate
 const

(2012/12/10 10:03), H. Peter Anvin wrote:
> Yes, if you add a * it becomes an array of pointers.

Right, I would like to make each pointer in the array read-only.

And, of course, the data itself which pointed by the pointer
is already protected.
You can see this in (builddir)/arch/x86/lib/inat_table.c
----
/* Table: 2-byte opcode (0x0f) */
const insn_attr_t inat_escape_table_1[INAT_OPCODE_TABLE_SIZE] = {
[...]
/* Escape opcode map array */
const insn_attr_t * const inat_escape_tables[INAT_ESC_MAX + 1][INAT_LSTPFX_MAX +
 1] = {
        [1][0] = inat_escape_table_1,
----

So I think Cong's v3 is good :)

Thank you,

> 
> Masami Hiramatsu <masami.hiramatsu.pt@...achi.com> wrote:
> 
>> (2012/12/10 0:50), H. Peter Anvin wrote:
>>> No, that would really be wrong - changing the type.
>>
>> What would be wrong? IMHO, this is just a fix to add a fool
>> proof 'const' to array instance itself.
>> ...Or, am I missed anything?
>>
>> Thank you,
>>
>>> Masami Hiramatsu <masami.hiramatsu.pt@...achi.com> wrote:
>>>
>>>> (2012/12/08 8:17), Cong Ding wrote:
>>>>>>>>>> Patch description please?
>>>>>>>>> there are 2 consts in the definition of one variable
>>>>>>>>>
>>>>>>>>
>>>>>>>> Please put in an actual patch description.  The first line
>>>> (subject
>>>>>>>> line) is a title; the patch should make sense without it.
>>>>>>> sorry for that. so like this is fine?
>>>>>>>
>>>>>>
>>>>>> Well, except that typically you should explain which variable it
>> is.
>>>>>> Yes, it is obvious if you look at the patch, but you're making the
>>>>>> reader spend a few more moments than necessary.
>>>>>>
>>>>>> Also, you should explain what the harm is -- if it breaks anything
>>>>>> or is just a cosmetic issue.
>>>>> sorry again for lacking of experience...
>>>>> and I missed another same error, so send version 2.
>>>>
>>>> Ah, sorry for my mistake. I would like to make both the value
>>>> pointed by the pointers and the pointers itself read-only.
>>>> Thus the right way of the patch should be;
>>>>
>>>> -	print "const insn_attr_t const *inat_escape_tables[INAT_ESC_MAX +
>> 1]"
>>>> \
>>>> +	print "const insn_attr_t * const inat_escape_tables[INAT_ESC_MAX +
>>>> 1]" \
>>>>
>>>> Cong, could you update your patch? then I can Ack that.
>>>>
>>>> Thank you,
>>>>
>>>>>
>>>>> - cong
>>>>> ---
>>>>> From 6cf729b913287a6fc06325ca75ccf0efff9274e8 Mon Sep 17 00:00:00
>>>> 2001
>>>>> From: Cong Ding <dinggnu@...il.com>
>>>>> Date: Fri, 7 Dec 2012 23:14:32 +0000
>>>>> Subject: [PATCH] arch/x86/tools/gen-insn-attr-x86.awk: remove
>>>> duplicate const
>>>>>
>>>>> fix the following sparse warning:
>>>>> arch/x86/lib/inat-tables.c:1080:25: warning: duplicate const
>>>>> arch/x86/lib/inat-tables.c:1095:25: warning: duplicate const
>>>>> arch/x86/lib/inat-tables.c:1118:25: warning: duplicate const
>>>>>
>>>>> for variable inat_escape_tables, inat_group_tables, and
>>>> inat_avx_tables
>>>>>
>>>>> Signed-off-by: Cong Ding <dinggnu@...il.com>
>>>>> ---
>>>>>  arch/x86/tools/gen-insn-attr-x86.awk |    6 +++---
>>>>>  1 files changed, 3 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/arch/x86/tools/gen-insn-attr-x86.awk
>>>> b/arch/x86/tools/gen-insn-attr-x86.awk
>>>>> index ddcf39b..987c7b2 100644
>>>>> --- a/arch/x86/tools/gen-insn-attr-x86.awk
>>>>> +++ b/arch/x86/tools/gen-insn-attr-x86.awk
>>>>> @@ -356,7 +356,7 @@ END {
>>>>>  		exit 1
>>>>>  	# print escape opcode map's array
>>>>>  	print "/* Escape opcode map array */"
>>>>> -	print "const insn_attr_t const *inat_escape_tables[INAT_ESC_MAX +
>>>> 1]" \
>>>>> +	print "const insn_attr_t *inat_escape_tables[INAT_ESC_MAX + 1]" \
>>>>>  	      "[INAT_LSTPFX_MAX + 1] = {"
>>>>>  	for (i = 0; i < geid; i++)
>>>>>  		for (j = 0; j < max_lprefix; j++)
>>>>> @@ -365,7 +365,7 @@ END {
>>>>>  	print "};\n"
>>>>>  	# print group opcode map's array
>>>>>  	print "/* Group opcode map array */"
>>>>> -	print "const insn_attr_t const *inat_group_tables[INAT_GRP_MAX +
>>>> 1]"\
>>>>> +	print "const insn_attr_t *inat_group_tables[INAT_GRP_MAX + 1]"\
>>>>>  	      "[INAT_LSTPFX_MAX + 1] = {"
>>>>>  	for (i = 0; i < ggid; i++)
>>>>>  		for (j = 0; j < max_lprefix; j++)
>>>>> @@ -374,7 +374,7 @@ END {
>>>>>  	print "};\n"
>>>>>  	# print AVX opcode map's array
>>>>>  	print "/* AVX opcode map array */"
>>>>> -	print "const insn_attr_t const *inat_avx_tables[X86_VEX_M_MAX +
>>>> 1]"\
>>>>> +	print "const insn_attr_t *inat_avx_tables[X86_VEX_M_MAX + 1]"\
>>>>>  	      "[INAT_LSTPFX_MAX + 1] = {"
>>>>>  	for (i = 0; i < gaid; i++)
>>>>>  		for (j = 0; j < max_lprefix; j++)
>>>>>
>>>
> 


-- 
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com


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