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From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Jes Sorensen <jes.sorensen@gmail.com>, Kalle Valo <kvalo@codeaurora.org>
Cc: Joe Perches <joe@perches.com>,
	Ulrich Kunitz <kune@deine-taler.de>,
	"David S. Miller" <davem@davemloft.net>,
	linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH][next] zd1211rw/zd_usb.h: Replace zero-length array with flexible-array member
Date: Tue, 10 Mar 2020 17:36:39 -0500	[thread overview]
Message-ID: <948ec681-c4ee-3479-8d8b-5aa1e358ec04@embeddedor.com> (raw)
In-Reply-To: <9700b2c9-1029-60b0-c5d2-684bdcede354@gmail.com>



On 3/10/20 5:34 PM, Jes Sorensen wrote:
> On 3/10/20 6:31 PM, Gustavo A. R. Silva wrote:
>>
>>
>> On 3/10/20 5:20 PM, Jes Sorensen wrote:
>>> On 3/10/20 6:13 PM, Gustavo A. R. Silva wrote:
>>>>
>>>>
>>>> On 3/10/20 5:07 PM, Jes Sorensen wrote:
>>>>> As I stated in my previous answer, this seems more code churn than an
>>>>> actual fix. If this is a real problem, shouldn't the work be put into
>>>>> fixing the compiler to handle foo[0] instead? It seems that is where the
>>>>> real value would be.
>>>>
>>>> Yeah. But, unfortunately, I'm not a compiler guy, so I'm not able to fix the
>>>> compiler as you suggest. And I honestly don't see what is so annoying/disturbing
>>>> about applying a patch that removes the 0 from foo[0] when it brings benefit
>>>> to the whole codebase.
>>>
>>> My point is that it adds what seems like unnecessary churn, which is not
>>> a benefit, and it doesn't improve the generated code.
>>>
>>
>> As an example of one of the benefits of this is that the compiler won't trigger
>> a warning in the following case:
>>
>> struct boo {
>> 	int stuff;
>> 	struct foo array[0];
>> 	int morestuff;
>> };
>>
>> The result of the code above is an undefined behavior.
>>
>> On the other hand in the case below, the compiles does trigger a warning:
>>
>> struct boo {
>> 	int stuff;
>> 	struct foo array[];
>> 	int morestuff;
>> };
> 
> Right, this just underlines my prior argument, that this should be fixed
> in the compiler.
> 

In the meantime it's not at all harmful to do something about it in the codebase.

Thanks
--
Gustavo

  reply	other threads:[~2020-03-10 22:37 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-05 11:12 Gustavo A. R. Silva
2020-03-05 14:50 ` Kalle Valo
2020-03-05 15:20   ` Joe Perches
2020-03-05 16:10     ` Kalle Valo
2020-03-05 18:28       ` Gustavo A. R. Silva
2020-03-10 13:56         ` Kalle Valo
2020-03-10 21:52           ` Gustavo A. R. Silva
2020-03-10 22:07             ` Jes Sorensen
2020-03-10 22:13               ` Gustavo A. R. Silva
2020-03-10 22:15                 ` Joe Perches
2020-03-10 22:21                   ` Gustavo A. R. Silva
2020-03-10 22:28                     ` Joe Perches
2020-03-10 22:33                       ` Jes Sorensen
2020-03-10 22:41                         ` Joe Perches
2020-03-10 22:46                           ` Gustavo A. R. Silva
2020-03-10 22:33                       ` Gustavo A. R. Silva
2020-03-10 22:20                 ` Jes Sorensen
2020-03-10 22:31                   ` Gustavo A. R. Silva
2020-03-10 22:34                     ` Jes Sorensen
2020-03-10 22:36                       ` Gustavo A. R. Silva [this message]
2020-03-23 16:46                         ` Kalle Valo
2020-03-23 17:14 ` [PATCH][next] zd1211rw: " Kalle Valo

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