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

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Message-ID: <4d60e086-92a3-f692-e7b5-1c75e913709e@samsung.com>
Date:   Wed, 24 Jun 2020 16:48:50 +0200
From:   Andrzej Hajda <a.hajda@...sung.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Jernej Skrabec <jernej.skrabec@...l.net>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-kernel@...r.kernel.org,
        "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Neil Armstrong <narmstrong@...libre.com>,
        Jonas Karlman <jonas@...boo.se>, andy.shevchenko@...il.com,
        Mark Brown <broonie@...nel.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        linux-arm-kernel@...ts.infradead.org,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [RESEND PATCH v5 3/5] drivers core: allow probe_err accept
 integer and pointer types


On 24.06.2020 14:30, Greg Kroah-Hartman wrote:
> On Wed, Jun 24, 2020 at 01:41:25PM +0200, Andrzej Hajda 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>
>> ---
>>   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)
> Shouldn't that be "unsigned long" instead of "long"?  That's what we put
> pointers in last I looked...

Unless we know this is error inside pointer, in such case we follow 
practice from PTR_ERR function.


Regards

Andrzej


>
> thanks,
>
> greg k-h
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