linux-kernel - RE: [PATCH v2 -next] crypto: inside-secure

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Message-ID: <MN2PR20MB297342698B98343D49FC2C82CAB80@MN2PR20MB2973.namprd20.prod.outlook.com>
Date:   Wed, 4 Sep 2019 12:25:39 +0000
From:   Pascal Van Leeuwen <pvanleeuwen@...imatrix.com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
CC:     YueHaibing <yuehaibing@...wei.com>,
        "antoine.tenart@...tlin.com" <antoine.tenart@...tlin.com>,
        "herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "pvanleeuwen@...idesecure.com" <pvanleeuwen@...idesecure.com>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 -next] crypto: inside-secure - Fix build error without
 CONFIG_PCI

> -----Original Message-----
> From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> Sent: Wednesday, September 4, 2019 2:11 PM
> To: Pascal Van Leeuwen <pvanleeuwen@...imatrix.com>
> Cc: YueHaibing <yuehaibing@...wei.com>; antoine.tenart@...tlin.com;
> herbert@...dor.apana.org.au; davem@...emloft.net; pvanleeuwen@...idesecure.com; linux-
> crypto@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH v2 -next] crypto: inside-secure - Fix build error without CONFIG_PCI
> 
> On Wed, 4 Sep 2019 at 04:57, Pascal Van Leeuwen
> <pvanleeuwen@...imatrix.com> wrote:
> >
> >
> > > -----Original Message-----
> > > From: linux-crypto-owner@...r.kernel.org <linux-crypto-owner@...r.kernel.org> On
> Behalf Of
> > > YueHaibing
> > > Sent: Tuesday, September 3, 2019 3:45 AM
> > > To: antoine.tenart@...tlin.com; herbert@...dor.apana.org.au; davem@...emloft.net;
> > > pvanleeuwen@...idesecure.com
> > > Cc: linux-crypto@...r.kernel.org; linux-kernel@...r.kernel.org; YueHaibing
> > > <yuehaibing@...wei.com>
> > > Subject: [PATCH v2 -next] crypto: inside-secure - Fix build error without CONFIG_PCI
> > >
> > > If CONFIG_PCI is not set, building fails:
> > >
> > > rivers/crypto/inside-secure/safexcel.c: In function safexcel_request_ring_irq:
> > > drivers/crypto/inside-secure/safexcel.c:944:9: error: implicit declaration of function
> > > pci_irq_vector;
> > >  did you mean rcu_irq_enter? [-Werror=implicit-function-declaration]
> > >    irq = pci_irq_vector(pci_pdev, irqid);
> > >          ^~~~~~~~~~~~~~
> > >
> > > Use #ifdef block to guard this.
> > >
> > Actually, this is interesting. My *original* implementation was using
> > straight #ifdefs, but then I got review feedback stating that I should not
> > do that, as it's not compile testable, suggesting to use regular C if's
> > instead. Then there was quite some back-and-forth on the actual
> > implementation and I ended up with this.
> >
> > So now it turns out that doesn't work and I'm suggested to go full-circle
> > back to straight #ifdef's? Or is there some other way to make this work?
> > Because I don't know where to go from here ...
> >
> 
> 
> C conditionals are preferred over preprocessor conditional, but if the
> conditional code refers to symbols that are not declared when the
> Kconfig symbol is not defined, preprocessor conditionals are the only
> option.
> 
Sure, I get that. But I *had* the #ifdef's and then other people told me
to get rid of them. How is one supposed to know when which symbols are
declared exactly? Moreover, I feel that if #ifdef's are sometimes the
only way, then you should be careful providing feedback on the subject.

> This is the reason we have so many empty static inline functions in
> header files - it ensures that the symbols are declared even if the
> only invocations are from dead code.
> 
This ties back into my previous question: how am I supposed to know whether
stuff is nicely covered by these empty static inlines or not? If this
happens to be a hit-and-miss affair.

Note that I tested the code with the 2 platforms at my disposal - actually
the only 2 relevant platforms for this driver, if you ask me - and they
both compiled just fine, so I had no way of finding this "problem" myself.

> 
> > > Fixes: 625f269a5a7a ("crypto: inside-secure - add support for PCI based FPGA
> development
> > > board")
> > > Signed-off-by: YueHaibing <yuehaibing@...wei.com>
> > > ---
> > > v2: use 'ifdef' instead of 'IS_ENABLED'
> > > ---
> > >  drivers/crypto/inside-secure/safexcel.c | 13 ++++++++++---
> > >  1 file changed, 10 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/crypto/inside-secure/safexcel.c b/drivers/crypto/inside-
> > > secure/safexcel.c
> > > index e12a2a3..5253900 100644
> > > --- a/drivers/crypto/inside-secure/safexcel.c
> > > +++ b/drivers/crypto/inside-secure/safexcel.c
> > > @@ -937,7 +937,8 @@ static int safexcel_request_ring_irq(void *pdev, int irqid,
> > >       int ret, irq;
> > >       struct device *dev;
> > >
> > > -     if (IS_ENABLED(CONFIG_PCI) && is_pci_dev) {
> > > +#ifdef CONFIG_PCI
> > > +     if (is_pci_dev) {
> > >               struct pci_dev *pci_pdev = pdev;
> > >
> > >               dev = &pci_pdev->dev;
> > > @@ -947,7 +948,10 @@ static int safexcel_request_ring_irq(void *pdev, int irqid,
> > >                               irqid, irq);
> > >                       return irq;
> > >               }
> > > -     } else if (IS_ENABLED(CONFIG_OF)) {
> > > +     } else
> > > +#endif
> > > +     {
> > > +#ifdef CONFIG_OF
> > >               struct platform_device *plf_pdev = pdev;
> > >               char irq_name[6] = {0}; /* "ringX\0" */
> > >
> > > @@ -960,6 +964,7 @@ static int safexcel_request_ring_irq(void *pdev, int irqid,
> > >                               irq_name, irq);
> > >                       return irq;
> > >               }
> > > +#endif
> > >       }
> > >
> > >       ret = devm_request_threaded_irq(dev, irq, handler,
> > > @@ -1137,7 +1142,8 @@ static int safexcel_probe_generic(void *pdev,
> > >
> > >       safexcel_configure(priv);
> > >
> > > -     if (IS_ENABLED(CONFIG_PCI) && priv->version == EIP197_DEVBRD) {
> > > +#ifdef CONFIG_PCI
> > > +     if (priv->version == EIP197_DEVBRD) {
> > >               /*
> > >                * Request MSI vectors for global + 1 per ring -
> > >                * or just 1 for older dev images
> > > @@ -1153,6 +1159,7 @@ static int safexcel_probe_generic(void *pdev,
> > >                       return ret;
> > >               }
> > >       }
> > > +#endif
> > >
> > >       /* Register the ring IRQ handlers and configure the rings */
> > >       priv->ring = devm_kcalloc(dev, priv->config.rings,
> > > --
> > > 2.7.4
> > >
> >
> > Regards,
> > Pascal van Leeuwen
> > Silicon IP Architect, Multi-Protocol Engines @ Verimatrix
> > www.insidesecure.com

Regards,
Pascal van Leeuwen
Silicon IP Architect, Multi-Protocol Engines @ Verimatrix
www.insidesecure.com