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SubjectRe: [PATCH 1/3] driver core: add probe_err log helper
On Tue, Oct 16, 2018 at 10:22 AM Andrzej Hajda <a.hajda@samsung.com> wrote:
>
> During probe every time driver gets resource it should usually check for error
> printk some message if it is not -EPROBE_DEFER and return the error. This
> pattern is simple but requires adding few lines after any resource acquisition
> code, as a result it is often omited or implemented only partially.
> probe_err helps to replace such code seqences with simple call, so code:
> if (err != -EPROBE_DEFER)
> dev_err(dev, ...);
> return err;
> becomes:
> return probe_err(dev, err, ...);
>
> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
> ---
> drivers/base/core.c | 37 +++++++++++++++++++++++++++++++++++++
> include/linux/device.h | 2 ++
> 2 files changed, 39 insertions(+)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 04bbcd779e11..23fabefb217a 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -3067,6 +3067,43 @@ 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.
> + * 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, ...)
> +{
> + struct va_format vaf;
> + va_list args;
> +

> + if (err != -EPROBE_DEFER) {

Why not

if (err == ...)
return err;

...
return err;

?

Better to read, better to maintain. No?

> + va_start(args, fmt);
> +
> + vaf.fmt = fmt;
> + vaf.va = &args;
> +

> + __dev_printk(KERN_ERR, dev, &vaf);

It would be nice to print an error code as well, wouldn't it?

> + va_end(args);
> + }
> +
> + return err;
> +}
> +
> static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
> {
> return fwnode && !IS_ERR(fwnode->secondary);
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 90224e75ade4..06c2c797d132 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -1577,6 +1577,8 @@ do { \
> WARN_ONCE(condition, "%s %s: " format, \
> dev_driver_string(dev), dev_name(dev), ## arg)
>
> +int probe_err(const struct device *dev, int err, const char *fmt, ...);
> +
> /* Create alias, so I can be autoloaded. */
> #define MODULE_ALIAS_CHARDEV(major,minor) \
> MODULE_ALIAS("char-major-" __stringify(major) "-" __stringify(minor))
> --
> 2.18.0
>


--
With Best Regards,
Andy Shevchenko

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