linux-kernel - Re: [RESEND PATCH v5 3/5] drivers core: allow probe

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Date:   Wed, 24 Jun 2020 14:14:11 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Andrzej Hajda <a.hajda@...sung.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Neil Armstrong <narmstrong@...libre.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Daniel Vetter <daniel@...ll.ch>,
        "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>
Subject: Re: [RESEND PATCH v5 3/5] drivers core: allow probe_err accept
 integer and pointer types

On Wed, Jun 24, 2020 at 1:41 PM Andrzej Hajda <a.hajda@...sung.com> wrote:
>
> Many resource acquisition functions return error value encapsulated in
> pointer instead of integer value. To simplify coding we can use macro
> which will accept both types of error.
> With this patch user can use:
>         probe_err(dev, ptr, ...)
> instead of:
>         probe_err(dev, PTR_ERR(ptr), ...)
> Without loosing old functionality:
>         probe_err(dev, err, ...)
>
> Signed-off-by: Andrzej Hajda <a.hajda@...sung.com>

The separation of this change from patch [1/5] looks kind of artificial to me.

You are introducing a new function anyway, so why not to make it what
you want right away?

> ---
>  drivers/base/core.c    | 25 ++-----------------------
>  include/linux/device.h | 25 ++++++++++++++++++++++++-
>  2 files changed, 26 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 2a96954d5460..df283c62d9c0 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -3953,28 +3953,7 @@ define_dev_printk_level(_dev_info, KERN_INFO);
>
>  #endif
>
> -/**
> - * probe_err - probe error check and log helper
> - * @dev: the pointer to the struct device
> - * @err: error value to test
> - * @fmt: printf-style format string
> - * @...: arguments as specified in the format string
> - *
> - * This helper implements common pattern present in probe functions for error
> - * checking: print message if the error is not -EPROBE_DEFER and propagate it.
> - * In case of -EPROBE_DEFER it sets defer probe reason, which can be checked
> - * later by reading devices_deferred debugfs attribute.
> - * It replaces code sequence:
> - *     if (err != -EPROBE_DEFER)
> - *             dev_err(dev, ...);
> - *     return err;
> - * with
> - *     return probe_err(dev, err, ...);
> - *
> - * Returns @err.
> - *
> - */
> -int probe_err(const struct device *dev, int err, const char *fmt, ...)
> +int __probe_err(const struct device *dev, int err, const char *fmt, ...)
>  {
>         struct va_format vaf;
>         va_list args;
> @@ -3992,7 +3971,7 @@ int probe_err(const struct device *dev, int err, const char *fmt, ...)
>
>         return err;
>  }
> -EXPORT_SYMBOL_GPL(probe_err);
> +EXPORT_SYMBOL_GPL(__probe_err);
>
>  static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
>  {
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 40a90d9bf799..22d3c3d4f461 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -965,7 +965,30 @@ void device_links_supplier_sync_state_pause(void);
>  void device_links_supplier_sync_state_resume(void);
>
>  extern __printf(3, 4)
> -int probe_err(const struct device *dev, int err, const char *fmt, ...);
> +int __probe_err(const struct device *dev, int err, const char *fmt, ...);
> +
> +/**
> + * probe_err - probe error check and log helper
> + * @dev: the pointer to the struct device
> + * @err: error value to test, can be integer or pointer type
> + * @fmt: printf-style format string
> + * @...: arguments as specified in the format string
> + *
> + * This helper implements common pattern present in probe functions for error
> + * checking: print message if the error is not -EPROBE_DEFER and propagate it.
> + * In case of -EPROBE_DEFER it sets defer probe reason, which can be checked
> + * later by reading devices_deferred debugfs attribute.
> + * It replaces code sequence:
> + *     if (err != -EPROBE_DEFER)
> + *             dev_err(dev, ...);
> + *     return err;
> + * with
> + *     return probe_err(dev, err, ...);
> + *
> + * Returns @err.
> + *
> + */
> +#define probe_err(dev, err, args...) __probe_err(dev, (long)(err), args)
>
>  /* Create alias, so I can be autoloaded. */
>  #define MODULE_ALIAS_CHARDEV(major,minor) \
> --
> 2.17.1
>