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From:   =?UTF-8?B?T25kcmVqIE1vc27DocSNZWs=?= <omosnacek@gmail.com>
Date:   Fri, 16 Aug 2019 09:08:42 +0200
Message-ID: <CAAUqJDuzUPUW=qvhEo6tU==Ycw0aijJM9pQk5W50kw=EgEG3ow@mail.gmail.com>
Subject: Re: crypto: hisilicon - Fix warning on printing %p with dma_addr_t
To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     Zhou Wang <wangzhou1@hisilicon.com>, linux-crypto@vger.kernel.org
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pi 16. 8. 2019 o 9:02 Ondrej Mosn=C3=A1=C4=8Dek <omosnacek@gmail.com> nap=
=C3=ADsal(a):
> Hi Herbert,
>
> pi 16. 8. 2019 o 1:52 Herbert Xu <herbert@gondor.apana.org.au> nap=C3=ADs=
al(a):
> > On Thu, Aug 15, 2019 at 10:17:37PM +0800, Zhou Wang wrote:
> > >
> > > > -   dev_dbg(&qm->pdev->dev, "QM mailbox request to q%u: %u-%pad\n",=
 queue,
> > > > -           cmd, dma_addr);
> > > > +   dev_dbg(&qm->pdev->dev, "QM mailbox request to q%u: %u-%#lxad\n=
",
> > > > +           queue, cmd, (unsigned long)dma_addr);
> > >
> > > Thanks. However, to be honest I can't get why we fix it like this.
> > > Can you give me a clue?
> >
> > dma_addr_t is not a pointer.  It's an integer type and therefore
> > you need to print it out as such.
>
> According to Documentation/core-api/printk-formats.rst, %pad is the
> format specifier intended specifically for dma_addr_t [1], so perhaps
> the kbuild robot warning was in fact bogus?
>
> [1] https://www.kernel.org/doc/html/latest/core-api/printk-formats.html#d=
ma-address-types-dma-addr-t

Oh, wait, in that section it actually says "Passed by reference.", so
Zhou is most likely right that the proper fix is to pass a pointer to
the variable containing the address (I assume this is to make the
generic GCC's format checking pass even if dma_addr_t is not actually
a pointer).

>
> >
> > Actually my patch is buggy too, on some architectures it can be
> > a long long so we need to cast is such.
> >
> > Cheers,
> > --
> > Email: Herbert Xu <herbert@gondor.apana.org.au>
> > Home Page: http://gondor.apana.org.au/~herbert/
> > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt