[PATCH] device-mapper: use dynamic debug instead of compile-time config option

[PATCH] device-mapper: use dynamic debug instead of compile-time config option

[Hannes Reinecke]

Switch to use dynamic debug to avoid having recompile the kernel
just to enable debugging messages.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 include/linux/device-mapper.h | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index e2d506dd805e..3d4365fd3001 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -556,13 +556,8 @@ void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 #define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
 #define DMINFO_LIMIT(fmt, ...) pr_info_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
 
-#ifdef CONFIG_DM_DEBUG
-#define DMDEBUG(fmt, ...) printk(KERN_DEBUG DM_FMT(fmt), ##__VA_ARGS__)
+#define DMDEBUG(fmt, ...) pr_debug(DM_FMT(fmt), ##__VA_ARGS__)
 #define DMDEBUG_LIMIT(fmt, ...) pr_debug_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
-#else
-#define DMDEBUG(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
-#define DMDEBUG_LIMIT(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
-#endif
 
 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 			  0 : scnprintf(result + sz, maxlen - sz, x))
-- 
2.25.0

Re: [PATCH] device-mapper: use dynamic debug instead of compile-time config option

[Damien Le Moal]

On 2020/05/13 16:10, Hannes Reinecke wrote:
> Switch to use dynamic debug to avoid having recompile the kernel
> just to enable debugging messages.
> 
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---
>  include/linux/device-mapper.h | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> index e2d506dd805e..3d4365fd3001 100644
> --- a/include/linux/device-mapper.h
> +++ b/include/linux/device-mapper.h
> @@ -556,13 +556,8 @@ void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
>  #define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
>  #define DMINFO_LIMIT(fmt, ...) pr_info_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
>  
> -#ifdef CONFIG_DM_DEBUG

Can we remove this from Kconfig as a config option ?

> -#define DMDEBUG(fmt, ...) printk(KERN_DEBUG DM_FMT(fmt), ##__VA_ARGS__)
> +#define DMDEBUG(fmt, ...) pr_debug(DM_FMT(fmt), ##__VA_ARGS__)
>  #define DMDEBUG_LIMIT(fmt, ...) pr_debug_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
> -#else
> -#define DMDEBUG(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
> -#define DMDEBUG_LIMIT(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
> -#endif
>  
>  #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
>  			  0 : scnprintf(result + sz, maxlen - sz, x))
> 

Otherwise, looks good to me.

Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>


-- 
Damien Le Moal
Western Digital Research

Re: [PATCH] device-mapper: use dynamic debug instead of compile-time config option

[Hannes Reinecke]

On 5/13/20 11:41 AM, Damien Le Moal wrote:
> On 2020/05/13 16:10, Hannes Reinecke wrote:
>> Switch to use dynamic debug to avoid having recompile the kernel
>> just to enable debugging messages.
>>
>> Signed-off-by: Hannes Reinecke <hare@suse.de>
>> ---
>>   include/linux/device-mapper.h | 7 +------
>>   1 file changed, 1 insertion(+), 6 deletions(-)
>>
>> diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
>> index e2d506dd805e..3d4365fd3001 100644
>> --- a/include/linux/device-mapper.h
>> +++ b/include/linux/device-mapper.h
>> @@ -556,13 +556,8 @@ void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
>>   #define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
>>   #define DMINFO_LIMIT(fmt, ...) pr_info_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
>>   
>> -#ifdef CONFIG_DM_DEBUG
> 
> Can we remove this from Kconfig as a config option ?
> 
No, we can't, it's being used by dm-snap and dm-integrity.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke            Teamlead Storage & Networking
hare@suse.de                               +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer


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Re: device-mapper: use dynamic debug instead of compile-time config option

[Mike Snitzer]

On Wed, May 13 2020 at  7:10am -0400,
Hannes Reinecke <hare@suse.de> wrote:

> On 5/13/20 11:41 AM, Damien Le Moal wrote:
> >On 2020/05/13 16:10, Hannes Reinecke wrote:
> >>Switch to use dynamic debug to avoid having recompile the kernel
> >>just to enable debugging messages.
> >>
> >>Signed-off-by: Hannes Reinecke <hare@suse.de>
> >>---
> >>  include/linux/device-mapper.h | 7 +------
> >>  1 file changed, 1 insertion(+), 6 deletions(-)
> >>
> >>diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> >>index e2d506dd805e..3d4365fd3001 100644
> >>--- a/include/linux/device-mapper.h
> >>+++ b/include/linux/device-mapper.h
> >>@@ -556,13 +556,8 @@ void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
> >>  #define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
> >>  #define DMINFO_LIMIT(fmt, ...) pr_info_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
> >>-#ifdef CONFIG_DM_DEBUG
> >
> >Can we remove this from Kconfig as a config option ?
> >
> No, we can't, it's being used by dm-snap and dm-integrity.

Yeah, they provide additional debugging if its set.

But shouldn't we preserve old-style DMDEBUG if CONFIG_DM_DEBUG is set
(compile time printing of debugging) but if not set, use dynamic
debugging?

Think I'd prefer that as the incremental improvement... thoughts?

Mike

Re: device-mapper: use dynamic debug instead of compile-time config option

[Hannes Reinecke]

On 5/13/20 6:25 PM, Mike Snitzer wrote:
> On Wed, May 13 2020 at  7:10am -0400,
> Hannes Reinecke <hare@suse.de> wrote:
> 
>> On 5/13/20 11:41 AM, Damien Le Moal wrote:
>>> On 2020/05/13 16:10, Hannes Reinecke wrote:
>>>> Switch to use dynamic debug to avoid having recompile the kernel
>>>> just to enable debugging messages.
>>>>
>>>> Signed-off-by: Hannes Reinecke <hare@suse.de>
>>>> ---
>>>>   include/linux/device-mapper.h | 7 +------
>>>>   1 file changed, 1 insertion(+), 6 deletions(-)
>>>>
>>>> diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
>>>> index e2d506dd805e..3d4365fd3001 100644
>>>> --- a/include/linux/device-mapper.h
>>>> +++ b/include/linux/device-mapper.h
>>>> @@ -556,13 +556,8 @@ void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
>>>>   #define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
>>>>   #define DMINFO_LIMIT(fmt, ...) pr_info_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
>>>> -#ifdef CONFIG_DM_DEBUG
>>>
>>> Can we remove this from Kconfig as a config option ?
>>>
>> No, we can't, it's being used by dm-snap and dm-integrity.
> 
> Yeah, they provide additional debugging if its set.
> 
> But shouldn't we preserve old-style DMDEBUG if CONFIG_DM_DEBUG is set
> (compile time printing of debugging) but if not set, use dynamic
> debugging?
> 
> Think I'd prefer that as the incremental improvement... thoughts?
> 
Works for me; I just don't want to recompile the kernel anytime I need 
to debug device-mapper stuff.

Will be resending.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke            Teamlead Storage & Networking
hare@suse.de                               +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer


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Re: device-mapper: use dynamic debug instead of compile-time config option

[Mike Snitzer]

On Wed, May 13 2020 at  1:01pm -0400,
Hannes Reinecke <hare@suse.de> wrote:

> On 5/13/20 6:25 PM, Mike Snitzer wrote:
> >On Wed, May 13 2020 at  7:10am -0400,
> >Hannes Reinecke <hare@suse.de> wrote:
> >
> >>On 5/13/20 11:41 AM, Damien Le Moal wrote:
> >>>On 2020/05/13 16:10, Hannes Reinecke wrote:
> >>>>Switch to use dynamic debug to avoid having recompile the kernel
> >>>>just to enable debugging messages.
> >>>>
> >>>>Signed-off-by: Hannes Reinecke <hare@suse.de>
> >>>>---
> >>>>  include/linux/device-mapper.h | 7 +------
> >>>>  1 file changed, 1 insertion(+), 6 deletions(-)
> >>>>
> >>>>diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> >>>>index e2d506dd805e..3d4365fd3001 100644
> >>>>--- a/include/linux/device-mapper.h
> >>>>+++ b/include/linux/device-mapper.h
> >>>>@@ -556,13 +556,8 @@ void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
> >>>>  #define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
> >>>>  #define DMINFO_LIMIT(fmt, ...) pr_info_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
> >>>>-#ifdef CONFIG_DM_DEBUG
> >>>
> >>>Can we remove this from Kconfig as a config option ?
> >>>
> >>No, we can't, it's being used by dm-snap and dm-integrity.
> >
> >Yeah, they provide additional debugging if its set.
> >
> >But shouldn't we preserve old-style DMDEBUG if CONFIG_DM_DEBUG is set
> >(compile time printing of debugging) but if not set, use dynamic
> >debugging?
> >
> >Think I'd prefer that as the incremental improvement... thoughts?
> >
> Works for me; I just don't want to recompile the kernel anytime I
> need to debug device-mapper stuff.
> 
> Will be resending.

Does the use of pr_debug() cause missing newlines (with your patch)?

Only thought to ask this because I'm chasing another DM issue at the
moment and happened to see __dm_suspend()'s use of pr_debug() includes
an explicit extra \n.

Mike

Re: device-mapper: use dynamic debug instead of compile-time config option

[Hannes Reinecke]

On 5/13/20 7:10 PM, Mike Snitzer wrote:
> On Wed, May 13 2020 at  1:01pm -0400,
> Hannes Reinecke <hare@suse.de> wrote:
> 
>> On 5/13/20 6:25 PM, Mike Snitzer wrote:
>>> On Wed, May 13 2020 at  7:10am -0400,
>>> Hannes Reinecke <hare@suse.de> wrote:
>>>
>>>> On 5/13/20 11:41 AM, Damien Le Moal wrote:
>>>>> On 2020/05/13 16:10, Hannes Reinecke wrote:
>>>>>> Switch to use dynamic debug to avoid having recompile the kernel
>>>>>> just to enable debugging messages.
>>>>>>
>>>>>> Signed-off-by: Hannes Reinecke <hare@suse.de>
>>>>>> ---
>>>>>>   include/linux/device-mapper.h | 7 +------
>>>>>>   1 file changed, 1 insertion(+), 6 deletions(-)
>>>>>>
>>>>>> diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
>>>>>> index e2d506dd805e..3d4365fd3001 100644
>>>>>> --- a/include/linux/device-mapper.h
>>>>>> +++ b/include/linux/device-mapper.h
>>>>>> @@ -556,13 +556,8 @@ void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
>>>>>>   #define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
>>>>>>   #define DMINFO_LIMIT(fmt, ...) pr_info_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
>>>>>> -#ifdef CONFIG_DM_DEBUG
>>>>>
>>>>> Can we remove this from Kconfig as a config option ?
>>>>>
>>>> No, we can't, it's being used by dm-snap and dm-integrity.
>>>
>>> Yeah, they provide additional debugging if its set.
>>>
>>> But shouldn't we preserve old-style DMDEBUG if CONFIG_DM_DEBUG is set
>>> (compile time printing of debugging) but if not set, use dynamic
>>> debugging?
>>>
>>> Think I'd prefer that as the incremental improvement... thoughts?
>>>
>> Works for me; I just don't want to recompile the kernel anytime I
>> need to debug device-mapper stuff.
>>
>> Will be resending.
> 
> Does the use of pr_debug() cause missing newlines (with your patch)?
> 
> Only thought to ask this because I'm chasing another DM issue at the
> moment and happened to see __dm_suspend()'s use of pr_debug() includes
> an explicit extra \n.
> 
Hmm. Not that I've noticed; but yeah, typically one would have to add 
'\n' to any of the pr_XXX calls. But then it depends on the wrapper 
being used. I'll check.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke            Teamlead Storage & Networking
hare@suse.de                               +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer


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