From: Stephen Rothwell <sfr@canb.auug.org.au>
To: Richard Yang <weiyang@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-next@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: linux-next: build warnings after merge of the akpm tree
Date: Fri, 26 Oct 2012 01:16:45 +1100 [thread overview]
Message-ID: <20121026011645.5a4e6adac51cf0bdc44e48bc@canb.auug.org.au> (raw)
In-Reply-To: <20121025141232.GB4730@richard.(null)>
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Hi Richard,
On Thu, 25 Oct 2012 22:12:32 +0800 Richard Yang <weiyang@linux.vnet.ibm.com> wrote:
>
> I did a quick check.
>
> The root reason is,
> 1. kfifo_in() second parameter should be type "const void *"
> 2. kfifo_out_locked() second parameter should be type "void *"
> 3. kfifo_in_locked() second parameter should be type "const void *"
>
> And I am curious about why the original code couldn't detect this type
> mismatch.
>
> The reason is: the original code use = not ==.
> so when a const void * is assigned another pointer type, there is no warning.
>
> While I write this test code, there is still no warning.
> int main()
> {
> int *a;
> void* b;
> b = a; // this should be ok.
> a = b; // this should need the type transfer, but still no warning.
> return 0;
> }
>
> Hmm... not understand. Any error in my test code?
Yes, any pointer can be assigned to a void pointer and a void pointer can
be assigned to any pointer, so neither of the above should complain.
--
Cheers,
Stephen Rothwell sfr@canb.auug.org.au
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next prev parent reply other threads:[~2012-10-25 14:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-25 3:28 linux-next: build warnings after merge of the akpm tree Stephen Rothwell
2012-10-25 3:30 ` Stephen Rothwell
[not found] ` <20121025141232.GB4730@richard.(null)>
2012-10-25 14:16 ` Stephen Rothwell [this message]
[not found] ` <508948de.01dc440a.58ed.ffffff17SMTPIN_ADDED@mx.google.com>
2012-10-25 22:23 ` Andrew Morton
2012-10-25 23:50 ` Stephen Rothwell
[not found] ` <20121025223656.GA3805@richard.(null)>
2012-10-26 5:44 ` Stefani Seibold
[not found] ` <20121025130952.GA4730@richard.(null)>
2012-10-25 14:20 ` Stephen Rothwell
2012-11-29 6:19 Stephen Rothwell
2012-11-29 7:24 ` Lars Ellenberg
2016-11-24 5:20 Stephen Rothwell
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