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SubjectRE: [PATCH 3/3] crypto: inside-secure - Remove #ifdef checks
Date
Hi Arnd,

Sorry for not responding earlier, but I've been very busy lately.
So I'm looking at this now for the first time.

> -----Original Message-----
> From: Arnd Bergmann <arnd@arndb.de>
> Sent: Monday, September 30, 2019 2:15 PM
> To: Antoine Tenart <antoine.tenart@bootlin.com>; Herbert Xu <herbert@gondor.apana.org.au>;
> David S. Miller <davem@davemloft.net>; Bjorn Helgaas <bhelgaas@google.com>
> Cc: Arnd Bergmann <arnd@arndb.de>; Pascal Van Leeuwen <pvanleeuwen@verimatrix.com>; Pascal van
> Leeuwen <pascalvanl@gmail.com>; Kelsey Skunberg <skunberg.kelsey@gmail.com>; linux-
> crypto@vger.kernel.org; linux-kernel@vger.kernel.org; linux-pci@vger.kernel.org
> Subject: [PATCH 3/3] crypto: inside-secure - Remove #ifdef checks
>
> When both PCI and OF are disabled, no drivers are registered, and
> we get some unused-function warnings:
>
> drivers/crypto/inside-secure/safexcel.c:1221:13: error: unused function
> 'safexcel_unregister_algorithms' [-Werror,-Wunused-function]
> static void safexcel_unregister_algorithms(struct safexcel_crypto_priv *priv)
> drivers/crypto/inside-secure/safexcel.c:1307:12: error: unused function
> 'safexcel_probe_generic' [-Werror,-Wunused-function]
> static int safexcel_probe_generic(void *pdev,
> drivers/crypto/inside-secure/safexcel.c:1531:13: error: unused function
> 'safexcel_hw_reset_rings' [-Werror,-Wunused-function]
> static void safexcel_hw_reset_rings(struct safexcel_crypto_priv *priv)
>
> It's better to make the compiler see what is going on and remove
> such ifdef checks completely. In case of PCI, this is trivial since
> pci_register_driver() is defined to an empty function that makes the
> compiler subsequently drop all unused code silently.
>
> The global pcireg_rc/ofreg_rc variables are not actually needed here
> since the driver registration does not fail in ways that would make
> it helpful.
>
> For CONFIG_OF, an IS_ENABLED() check is still required, since platform
> drivers can exist both with and without it.
>
> A little change to linux/pci.h is needed to ensure that
> pcim_enable_device() is visible to the driver. Moving the declaration
> outside of ifdef would be sufficient here, but for consistency with the
> rest of the file, adding an inline helper is probably best.
>
> Fixes: 212ef6f29e5b ("crypto: inside-secure - Fix unused variable warning when CONFIG_PCI=n")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/crypto/inside-secure/safexcel.c | 49 ++++++-------------------
> include/linux/pci.h | 1 +
> 2 files changed, 13 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/crypto/inside-secure/safexcel.c b/drivers/crypto/inside-secure/safexcel.c
> index 311bf60df39f..c4e8fd27314c 100644
> --- a/drivers/crypto/inside-secure/safexcel.c
> +++ b/drivers/crypto/inside-secure/safexcel.c
> @@ -1547,7 +1547,6 @@ static void safexcel_hw_reset_rings(struct safexcel_crypto_priv *priv)
> }
> }
>
> -#if IS_ENABLED(CONFIG_OF)
> /* for Device Tree platform driver */
>
> static int safexcel_probe(struct platform_device *pdev)
> @@ -1666,9 +1665,7 @@ static struct platform_driver crypto_safexcel = {
> .of_match_table = safexcel_of_match_table,
> },
> };
> -#endif
>
> -#if IS_ENABLED(CONFIG_PCI)
> /* PCIE devices - i.e. Inside Secure development boards */
>
> static int safexcel_pci_probe(struct pci_dev *pdev,
> @@ -1789,54 +1786,32 @@ static struct pci_driver safexcel_pci_driver = {
> .probe = safexcel_pci_probe,
> .remove = safexcel_pci_remove,
> };
> -#endif
> -
> -/* Unfortunately, we have to resort to global variables here */
> -#if IS_ENABLED(CONFIG_PCI)
> -int pcireg_rc = -EINVAL; /* Default safe value */
> -#endif
> -#if IS_ENABLED(CONFIG_OF)
> -int ofreg_rc = -EINVAL; /* Default safe value */
> -#endif
>
> static int __init safexcel_init(void)
> {
> -#if IS_ENABLED(CONFIG_PCI)
> + int ret;
> +
> /* Register PCI driver */
> - pcireg_rc = pci_register_driver(&safexcel_pci_driver);
> -#endif
> + ret = pci_register_driver(&safexcel_pci_driver);
>
> -#if IS_ENABLED(CONFIG_OF)
> /* Register platform driver */
> - ofreg_rc = platform_driver_register(&crypto_safexcel);
> - #if IS_ENABLED(CONFIG_PCI)
> - /* Return success if either PCI or OF registered OK */
> - return pcireg_rc ? ofreg_rc : 0;
> - #else
> - return ofreg_rc;
> - #endif
> -#else
> - #if IS_ENABLED(CONFIG_PCI)
> - return pcireg_rc;
> - #else
> - return -EINVAL;
> - #endif
> -#endif
> + if (IS_ENABLED(CONFIG_OF) && !ret) {
>
Hmm ... this would make it skip the OF registration if the PCIE
registration failed. Note that the typical embedded system will
have a PCIE subsystem (e.g. Marvell A7K/A8K does) but will have
the EIP embedded on the SoC as an OF device.

So the question is: is it possible somehow that PCIE registration
fails while OF registration does pass? Because in that case, this
code would be wrong ...

Other than that, I don't care much how this code is implemented
as long as it works for both my use cases, being an OF embedded
device (on a SoC _with_ or _without_ PCIE support) and a device
on a PCIE board in a PCI (which has both PCIE and OF support).

> + ret = platform_driver_register(&crypto_safexcel);
> + if (ret)
> + pci_unregister_driver(&safexcel_pci_driver);
> + }
> +
> + return ret;
> }
>
> static void __exit safexcel_exit(void)
> {
> -#if IS_ENABLED(CONFIG_OF)
> /* Unregister platform driver */
> - if (!ofreg_rc)
> + if (IS_ENABLED(CONFIG_OF))
> platform_driver_unregister(&crypto_safexcel);
> -#endif
>
> -#if IS_ENABLED(CONFIG_PCI)
> /* Unregister PCI driver if successfully registered before */
> - if (!pcireg_rc)
> - pci_unregister_driver(&safexcel_pci_driver);
> -#endif
> + pci_unregister_driver(&safexcel_pci_driver);
> }
>
> module_init(safexcel_init);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index f9088c89a534..1a6cf19eac2d 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1686,6 +1686,7 @@ static inline struct pci_dev *pci_get_class(unsigned int class,
> static inline void pci_set_master(struct pci_dev *dev) { }
> static inline int pci_enable_device(struct pci_dev *dev) { return -EIO; }
> static inline void pci_disable_device(struct pci_dev *dev) { }
> +static inline int pcim_enable_device(struct pci_dev *pdev) { return -EIO; }
> static inline int pci_assign_resource(struct pci_dev *dev, int i)
> { return -EBUSY; }
> static inline int __pci_register_driver(struct pci_driver *drv,
> --
> 2.20.0

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

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