linux-kernel - Re: [PATCHv2 1/2] dev-core: fix build break when DEBUG is enabled

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Message-ID: <521CE2C9.1010002@akamai.com>
Date:	Tue, 27 Aug 2013 13:32:57 -0400
From:	Jason Baron <jbaron@...mai.com>
To:	Joe Perches <joe@...ches.com>
CC:	Dmitry Kasatkin <d.kasatkin@...sung.com>,
	Hiroshi Doyu <hdoyu@...dia.com>,
	"sarah.a.sharp@...ux.intel.com" <sarah.a.sharp@...ux.intel.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"dmitry.kasatkin@...il.com" <dmitry.kasatkin@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv2 1/2] dev-core: fix build break when DEBUG is enabled

On 08/27/2013 12:20 PM, Joe Perches wrote:
> On Tue, 2013-08-27 at 17:47 +0300, Dmitry Kasatkin wrote:
>> When DEBUG is defined, dev_dbg_ratelimited uses dynamic debug data
>> structures even when CONFIG_DYNAMIC_DEBUG is not defined.
>> It leads to build break.
>> For example, when I try to use dev_dbg_ratelimited in USB code and
>> CONFIG_USB_DEBUG is enabled, but CONFIG_DYNAMIC_DEBUG is not, I get:
> Jason?
>
> Seems mostly sensible to me but I think the first check
> needs to be
>
> #if defined(CONFIG_DYNAMIC_DEBUG) && defined(DEBUG)

Why? All the other call-sites, do it the way Dmitry has done it.

> Also, it's curious why it was ever using __dynamic_pr_debug
> instead of __dynamic_dev_dbg

Not sure.

> Maybe for completeness there should be a
> dev_vdbg_ratelimited too.

I could also see the rate limiting being pushed further down, such that
dynamic debug could control how and whether or not its enabled.


Thanks,

-Jason

> Additional bit below...
>
>>   CC [M]  drivers/usb/host/xhci-ring.o
>>   drivers/usb/host/xhci-ring.c: In function ‘xhci_queue_intr_tx’:
>>   drivers/usb/host/xhci-ring.c:3059:3: error: implicit declaration of function ‘DEFINE_DYNAMIC_DEBUG_METADATA’ [-Werror=implicit-function-declaration]
>>   drivers/usb/host/xhci-ring.c:3059:3: error: ‘descriptor’ undeclared (first use in this function)
>>   drivers/usb/host/xhci-ring.c:3059:3: note: each undeclared identifier is reported only once for each function it appears in
>>   drivers/usb/host/xhci-ring.c:3059:3: error: implicit declaration of function ‘__dynamic_pr_debug’ [-Werror=implicit-function-declaration]
>>   drivers/usb/host/xhci-ring.c: In function ‘xhci_queue_isoc_tx_prepare’:
>>   drivers/usb/host/xhci-ring.c:3847:3: error: ‘descriptor’ undeclared (first use in this function)
>>   cc1: some warnings being treated as errors
>>   make[2]: *** [drivers/usb/host/xhci-ring.o] Error 1
>>   make[1]: *** [drivers/usb/host] Error 2
>>   make: *** [drivers/usb/] Error 2
>>
>> This patch separates definition for CONFIG_DYNAMIC_DEBUG and DEBUG cases.
>>
>> Signed-off-by: Dmitry Kasatkin <d.kasatkin@...sung.com>
>> ---
>>  include/linux/device.h | 17 ++++++++++++++---
>>  1 file changed, 14 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/linux/device.h b/include/linux/device.h
>> index 22b546a..d336beb 100644
>> --- a/include/linux/device.h
>> +++ b/include/linux/device.h
>> @@ -1099,17 +1099,28 @@ do {									\
>>  	dev_level_ratelimited(dev_notice, dev, fmt, ##__VA_ARGS__)
>>  #define dev_info_ratelimited(dev, fmt, ...)				\
>>  	dev_level_ratelimited(dev_info, dev, fmt, ##__VA_ARGS__)
>> -#if defined(CONFIG_DYNAMIC_DEBUG) || defined(DEBUG)
>> +#if defined(CONFIG_DYNAMIC_DEBUG)
> I think this needs to be
>
> #if defined(CONFIG_DYNAMIC_DEBUG) && defined(DEBUG)
>
>>  #define dev_dbg_ratelimited(dev, fmt, ...)				\
>>  do {									\
>>  	static DEFINE_RATELIMIT_STATE(_rs,				\
>>  				      DEFAULT_RATELIMIT_INTERVAL,	\
>>  				      DEFAULT_RATELIMIT_BURST);		\
>>  	DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);			\
>> +	/* descriptor check is first to prevent flooding with		\
>> +	   "callbacks suppressed" */					\
>>  	if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT) &&	\
>>  	    __ratelimit(&_rs))						\
>> -		__dynamic_pr_debug(&descriptor, pr_fmt(fmt),		\
>> -				   ##__VA_ARGS__);			\
>> +		__dynamic_dev_dbg(&descriptor, dev, fmt,		\
>> +				  ##__VA_ARGS__);			\
>> +} while (0)
>> +#elif defined(DEBUG)
>> +#define dev_dbg_ratelimited(dev, fmt, ...)				\
>> +do {									\
>> +	static DEFINE_RATELIMIT_STATE(_rs,				\
>> +				      DEFAULT_RATELIMIT_INTERVAL,	\
>> +				      DEFAULT_RATELIMIT_BURST);		\
>> +	if (__ratelimit(&_rs))						\
>> +		dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__);	\
>>  } while (0)
>>  #else
>>  #define dev_dbg_ratelimited(dev, fmt, ...)			\
>
>

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