From: Chen Gang <gang.chen@asianux.com>
To: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
riel@redhat.com, hughd@google.com, xemul@parallels.com,
Wanpeng Li <liwanp@linux.vnet.ibm.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2] mm/shmem.c: check the return value of mpol_to_str()
Date: Mon, 16 Sep 2013 11:17:21 +0800 [thread overview]
Message-ID: <52367841.1020506@asianux.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1309131413130.31480@chino.kir.corp.google.com>
On 09/14/2013 05:14 AM, David Rientjes wrote:
> On Thu, 12 Sep 2013, Chen Gang wrote:
>
>> Hmm... for extern function, at present, maybe you can guarantee, but may
>> not always in the future. And "Code is mainly for making readers 'happy'
>> (e.g version mergers), not writers".
>>
>> For extern function which more than 50 lines (used by 2 sub-systems), it
>> is strange for readers to find it no return value, also strange to let
>> *BUG_ON() on the extern function's input parameters directly.
>>
>> If one caller wants to treat failure as BUG, can "*BUG_ON(mpol_to_str()
>> < 0)", that will be more clearer to all members (need this patch do like
>> it? :-) ).
>>
>>
>> BTW: in my opinion, within mpol_to_str(), the VM_BUG_ON() need be
>> replaced by returning -EINVAL.
>>
>
> Are you reading my emails?
>
Yes.
> I'm asking for a compile-time error if the maxlen passed to mpol_to_str()
> is too small; it's a constant value and can be evaluated at compile-time.
> Then mpol_to_str() can return void if you simply store "unknown" when it's
> an unknown mode.
>
Are/were you saying: 'gcc' can realize an extern functions' input
parameter whether is a constant??
If so, excuse me, I really did not quite understand what you were
saying, but I am still trying to understand.
As far as I know:
mpol_to_str() is called by 2 areas, which will input different maxlen.
for a none-inline function, compiler treats parameters as variables.
for ANSI C compiler, for function's parameter, "array == pointer".
Hmm... maybe you see 'sizeof()'? if so, we also need notice: "multiple
callers only call one callee with there different 'sizeof()'", callee
has to treat these 'sizeof()' values as variable, not constant.
If I am still misunderstanding, please say more with details, thanks.
> Sheesh.
>
>
Thanks.
--
Chen Gang
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next prev parent reply other threads:[~2013-09-16 3:18 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-20 3:56 [PATCH 0/3] mm: mempolicy: the failure processing about mpol_to_str() Chen Gang
2013-08-20 3:56 ` Chen Gang
2013-08-20 3:57 ` [PATCH 1/3] mm/mempolicy.c: still fill buffer as full as possible when buffer space is not enough in mpol_to_str() Chen Gang
2013-08-20 3:57 ` Chen Gang
2013-08-20 3:58 ` [PATCH 2/3] fs/proc/task_mmu.c: check the return value of mpol_to_str() Chen Gang
2013-08-20 3:58 ` Chen Gang
2013-08-20 3:59 ` [PATCH 3/3] mm/shmem.c: " Chen Gang
2013-08-20 3:59 ` Chen Gang
2013-08-20 5:30 ` [PATCH 0/3] mm: mempolicy: the failure processing about mpol_to_str() Cyrill Gorcunov
2013-08-20 5:30 ` Cyrill Gorcunov
2013-08-20 5:41 ` Chen Gang
2013-08-20 5:41 ` Chen Gang
2013-08-20 6:47 ` Cyrill Gorcunov
2013-08-20 6:47 ` Cyrill Gorcunov
2013-08-20 7:48 ` Chen Gang
2013-08-20 7:48 ` Chen Gang
2013-08-20 7:51 ` Chen Gang
2013-08-20 7:51 ` Chen Gang
2013-08-20 8:09 ` Chen Gang
2013-08-20 8:09 ` Chen Gang
2013-08-20 8:13 ` Chen Gang F T
2013-08-20 8:13 ` Chen Gang F T
2013-08-20 8:20 ` Chen Gang
2013-08-20 8:20 ` Chen Gang
2013-08-20 8:25 ` Cyrill Gorcunov
2013-08-20 8:25 ` Cyrill Gorcunov
2013-08-20 8:31 ` Chen Gang
2013-08-20 8:31 ` Chen Gang
2013-08-21 2:21 ` [PATCH 0/3] mm: shmem: check the return value of mpol_to_str() Chen Gang
2013-08-21 2:21 ` Chen Gang
2013-08-21 2:22 ` [PATCH 1/3] fs/proc/task_mmu.c: " Chen Gang
2013-08-21 2:22 ` Chen Gang
2013-08-21 2:23 ` [PATCH 2/3] mm/shmem.c: let shmem_show_mpol() return value Chen Gang
2013-08-21 2:23 ` Chen Gang
2013-08-21 2:24 ` [PATCH 3/3] mm/shmem.c: check the return value of mpol_to_str() Chen Gang
2013-08-21 2:24 ` Chen Gang
2013-08-21 22:03 ` [PATCH 2/3] mm/shmem.c: let shmem_show_mpol() return value Andrew Morton
2013-08-21 22:03 ` Andrew Morton
2013-08-22 0:52 ` Chen Gang
2013-08-22 0:52 ` Chen Gang
2013-08-22 1:04 ` [PATCH] mm/shmem.c: check the return value of mpol_to_str() Chen Gang
2013-08-22 1:04 ` Chen Gang
2013-09-03 5:32 ` Chen Gang
2013-09-03 5:32 ` Chen Gang
2013-09-05 0:24 ` [PATCH v2] " Chen Gang
2013-09-09 20:30 ` David Rientjes
2013-09-10 0:47 ` Chen Gang
2013-09-10 6:43 ` David Rientjes
2013-09-10 7:01 ` Chen Gang
2013-09-12 0:33 ` David Rientjes
2013-09-12 2:19 ` KOSAKI Motohiro
2013-09-12 3:13 ` Chen Gang
2013-09-13 21:12 ` David Rientjes
2013-09-14 2:51 ` KOSAKI Motohiro
2013-09-16 3:27 ` Chen Gang
2013-09-16 20:13 ` David Rientjes
2013-09-17 0:45 ` Chen Gang
2013-09-17 22:51 ` David Rientjes
2013-09-18 1:20 ` Chen Gang
2013-09-12 3:02 ` Chen Gang
2013-09-12 18:19 ` KOSAKI Motohiro
2013-09-13 2:23 ` Chen Gang
2013-09-13 16:50 ` KOSAKI Motohiro
2013-09-16 2:55 ` Chen Gang
2013-09-16 16:16 ` KOSAKI Motohiro
2013-09-17 1:10 ` Chen Gang
2013-09-17 22:53 ` David Rientjes
2013-09-18 1:37 ` Chen Gang
2013-09-18 22:17 ` David Rientjes
2013-09-13 21:14 ` David Rientjes
2013-09-16 3:17 ` Chen Gang [this message]
2013-09-25 2:58 ` [patch] mm, mempolicy: make mpol_to_str robust and always succeed David Rientjes
2013-09-25 2:58 ` David Rientjes
2013-09-25 3:11 ` Dave Jones
2013-09-25 3:11 ` Dave Jones
2013-09-25 3:18 ` David Rientjes
2013-09-25 3:18 ` David Rientjes
2013-09-25 3:25 ` Dave Jones
2013-09-25 3:25 ` Dave Jones
2013-09-25 17:58 ` David Rientjes
2013-09-25 17:58 ` David Rientjes
2013-09-25 21:30 ` Andrew Morton
2013-09-25 21:30 ` Andrew Morton
2013-09-25 22:06 ` David Rientjes
2013-09-25 22:06 ` David Rientjes
2013-08-21 5:31 ` [PATCH 0/3] mm: shmem: check the return value of mpol_to_str() Cyrill Gorcunov
2013-08-21 5:31 ` Cyrill Gorcunov
2013-08-21 5:48 ` Chen Gang
2013-08-21 5:48 ` Chen Gang
-- strict thread matches above, loose matches on Subject: below --
2013-09-19 0:31 [PATCH v2] mm/shmem.c: " Chen,Gang( 陈刚)
[not found] <20130919003142.B72EC1840296@intranet.asianux.com>
2013-09-23 21:46 ` David Rientjes
2013-09-24 2:28 ` Chen Gang
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