[PATCH] bitops: Introduce BITS_PER_TYPE

[PATCH] bitops: Introduce BITS_PER_TYPE

[Chris Wilson]

net_dim.h has a rather useful extension to BITS_PER_BYTE to compute the
number of bits in a type (BITS_PER_BYTE * sizeof(T)), so promote the
macro to bitops.h, alongside BITS_PER_BYTE, for wider usage.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Andy Gospodarek <gospo@broadcom.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
---
 include/linux/bitops.h  | 3 ++-
 include/linux/net_dim.h | 1 -
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 4cac4e1a72ff..091cb17d1a9b 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -11,7 +11,8 @@
 #define BIT_ULL_MASK(nr)	(1ULL << ((nr) % BITS_PER_LONG_LONG))
 #define BIT_ULL_WORD(nr)	((nr) / BITS_PER_LONG_LONG)
 #define BITS_PER_BYTE		8
-#define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
+#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
+#define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
 #endif
 
 /*
diff --git a/include/linux/net_dim.h b/include/linux/net_dim.h
index 29ed8fd6379a..14f1734e740a 100644
--- a/include/linux/net_dim.h
+++ b/include/linux/net_dim.h
@@ -326,7 +326,6 @@ static inline void net_dim_sample(u16 event_ctr,
 }
 
 #define NET_DIM_NEVENTS 64
-#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
 #define BIT_GAP(bits, end, start) ((((end) - (start)) + BIT_ULL(bits)) & (BIT_ULL(bits) - 1))
 
 static inline void net_dim_calc_stats(struct net_dim_sample *start,
-- 
2.18.0

Re: [PATCH] bitops: Introduce BITS_PER_TYPE

[Jani Nikula]

On Fri, 06 Jul 2018, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> net_dim.h has a rather useful extension to BITS_PER_BYTE to compute the
> number of bits in a type (BITS_PER_BYTE * sizeof(T)), so promote the
> macro to bitops.h, alongside BITS_PER_BYTE, for wider usage.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Andy Gospodarek <gospo@broadcom.com>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Ingo Molnar <mingo@kernel.org>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  include/linux/bitops.h  | 3 ++-
>  include/linux/net_dim.h | 1 -
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/bitops.h b/include/linux/bitops.h
> index 4cac4e1a72ff..091cb17d1a9b 100644
> --- a/include/linux/bitops.h
> +++ b/include/linux/bitops.h
> @@ -11,7 +11,8 @@
>  #define BIT_ULL_MASK(nr)	(1ULL << ((nr) % BITS_PER_LONG_LONG))
>  #define BIT_ULL_WORD(nr)	((nr) / BITS_PER_LONG_LONG)
>  #define BITS_PER_BYTE		8
> -#define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
> +#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
> +#define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
>  #endif
>  
>  /*
> diff --git a/include/linux/net_dim.h b/include/linux/net_dim.h
> index 29ed8fd6379a..14f1734e740a 100644
> --- a/include/linux/net_dim.h
> +++ b/include/linux/net_dim.h
> @@ -326,7 +326,6 @@ static inline void net_dim_sample(u16 event_ctr,
>  }
>  
>  #define NET_DIM_NEVENTS 64
> -#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
>  #define BIT_GAP(bits, end, start) ((((end) - (start)) + BIT_ULL(bits)) & (BIT_ULL(bits) - 1))
>  
>  static inline void net_dim_calc_stats(struct net_dim_sample *start,

-- 
Jani Nikula, Intel Open Source Graphics Center

Re: [PATCH] bitops: Introduce BITS_PER_TYPE

[Randy Dunlap]

On 07/06/18 02:44, Chris Wilson wrote:
> net_dim.h has a rather useful extension to BITS_PER_BYTE to compute the
> number of bits in a type (BITS_PER_BYTE * sizeof(T)), so promote the
> macro to bitops.h, alongside BITS_PER_BYTE, for wider usage.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Andy Gospodarek <gospo@broadcom.com>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Ingo Molnar <mingo@kernel.org>
> ---
>  include/linux/bitops.h  | 3 ++-
>  include/linux/net_dim.h | 1 -
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/bitops.h b/include/linux/bitops.h
> index 4cac4e1a72ff..091cb17d1a9b 100644
> --- a/include/linux/bitops.h
> +++ b/include/linux/bitops.h
> @@ -11,7 +11,8 @@
>  #define BIT_ULL_MASK(nr)	(1ULL << ((nr) % BITS_PER_LONG_LONG))
>  #define BIT_ULL_WORD(nr)	((nr) / BITS_PER_LONG_LONG)
>  #define BITS_PER_BYTE		8
> -#define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
> +#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
> +#define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
>  #endif
>  
>  /*

doesn't <linux/net_dim.h> need to #include <linux/bitops.h> ?


> diff --git a/include/linux/net_dim.h b/include/linux/net_dim.h
> index 29ed8fd6379a..14f1734e740a 100644
> --- a/include/linux/net_dim.h
> +++ b/include/linux/net_dim.h
> @@ -326,7 +326,6 @@ static inline void net_dim_sample(u16 event_ctr,
>  }
>  
>  #define NET_DIM_NEVENTS 64
> -#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
>  #define BIT_GAP(bits, end, start) ((((end) - (start)) + BIT_ULL(bits)) & (BIT_ULL(bits) - 1))
>  
>  static inline void net_dim_calc_stats(struct net_dim_sample *start,
> 


-- 
~Randy

Re: [PATCH] bitops: Introduce BITS_PER_TYPE

[Chris Wilson]

Quoting Randy Dunlap (2018-07-06 18:48:55)
> 
> On 07/06/18 02:44, Chris Wilson wrote:
> > net_dim.h has a rather useful extension to BITS_PER_BYTE to compute the
> > number of bits in a type (BITS_PER_BYTE * sizeof(T)), so promote the
> > macro to bitops.h, alongside BITS_PER_BYTE, for wider usage.
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Jani Nikula <jani.nikula@linux.intel.com>
> > Cc: Andy Gospodarek <gospo@broadcom.com>
> > Cc: David S. Miller <davem@davemloft.net>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Ingo Molnar <mingo@kernel.org>
> > ---
> >  include/linux/bitops.h  | 3 ++-
> >  include/linux/net_dim.h | 1 -
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/include/linux/bitops.h b/include/linux/bitops.h
> > index 4cac4e1a72ff..091cb17d1a9b 100644
> > --- a/include/linux/bitops.h
> > +++ b/include/linux/bitops.h
> > @@ -11,7 +11,8 @@
> >  #define BIT_ULL_MASK(nr)     (1ULL << ((nr) % BITS_PER_LONG_LONG))
> >  #define BIT_ULL_WORD(nr)     ((nr) / BITS_PER_LONG_LONG)
> >  #define BITS_PER_BYTE                8
> > -#define BITS_TO_LONGS(nr)    DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
> > +#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
> > +#define BITS_TO_LONGS(nr)    DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
> >  #endif
> >  
> >  /*
> 
> doesn't <linux/net_dim.h> need to #include <linux/bitops.h> ?

It already has to in order to obtain BITS_PER_BYTE. Just doesn't do so
directly.
-Chris

Re: [PATCH] bitops: Introduce BITS_PER_TYPE

[Randy Dunlap]

On 07/06/18 10:51, Chris Wilson wrote:
> Quoting Randy Dunlap (2018-07-06 18:48:55)
>>
>> On 07/06/18 02:44, Chris Wilson wrote:
>>> net_dim.h has a rather useful extension to BITS_PER_BYTE to compute the
>>> number of bits in a type (BITS_PER_BYTE * sizeof(T)), so promote the
>>> macro to bitops.h, alongside BITS_PER_BYTE, for wider usage.
>>>
>>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>>> Cc: Jani Nikula <jani.nikula@linux.intel.com>
>>> Cc: Andy Gospodarek <gospo@broadcom.com>
>>> Cc: David S. Miller <davem@davemloft.net>
>>> Cc: Thomas Gleixner <tglx@linutronix.de>
>>> Cc: Andrew Morton <akpm@linux-foundation.org>
>>> Cc: Ingo Molnar <mingo@kernel.org>
>>> ---
>>>  include/linux/bitops.h  | 3 ++-
>>>  include/linux/net_dim.h | 1 -
>>>  2 files changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/include/linux/bitops.h b/include/linux/bitops.h
>>> index 4cac4e1a72ff..091cb17d1a9b 100644
>>> --- a/include/linux/bitops.h
>>> +++ b/include/linux/bitops.h
>>> @@ -11,7 +11,8 @@
>>>  #define BIT_ULL_MASK(nr)     (1ULL << ((nr) % BITS_PER_LONG_LONG))
>>>  #define BIT_ULL_WORD(nr)     ((nr) / BITS_PER_LONG_LONG)
>>>  #define BITS_PER_BYTE                8
>>> -#define BITS_TO_LONGS(nr)    DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
>>> +#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
>>> +#define BITS_TO_LONGS(nr)    DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
>>>  #endif
>>>  
>>>  /*
>>
>> doesn't <linux/net_dim.h> need to #include <linux/bitops.h> ?
> 
> It already has to in order to obtain BITS_PER_BYTE. Just doesn't do so
> directly.

Right.  and does that work on all $ARCHes?

Please see Documentation/process/submit-checklist.rst, rule #1:
1) If you use a facility then #include the file that defines/declares
   that facility.  Don't depend on other header files pulling in ones
   that you use.


thanks,
-- 
~Randy

Re: [PATCH] bitops: Introduce BITS_PER_TYPE

[Chris Wilson]

Quoting Randy Dunlap (2018-07-06 18:55:57)
> On 07/06/18 10:51, Chris Wilson wrote:
> > Quoting Randy Dunlap (2018-07-06 18:48:55)
> >>
> >> On 07/06/18 02:44, Chris Wilson wrote:
> >>> net_dim.h has a rather useful extension to BITS_PER_BYTE to compute the
> >>> number of bits in a type (BITS_PER_BYTE * sizeof(T)), so promote the
> >>> macro to bitops.h, alongside BITS_PER_BYTE, for wider usage.
> >>>
> >>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> >>> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> >>> Cc: Andy Gospodarek <gospo@broadcom.com>
> >>> Cc: David S. Miller <davem@davemloft.net>
> >>> Cc: Thomas Gleixner <tglx@linutronix.de>
> >>> Cc: Andrew Morton <akpm@linux-foundation.org>
> >>> Cc: Ingo Molnar <mingo@kernel.org>
> >>> ---
> >>>  include/linux/bitops.h  | 3 ++-
> >>>  include/linux/net_dim.h | 1 -
> >>>  2 files changed, 2 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/include/linux/bitops.h b/include/linux/bitops.h
> >>> index 4cac4e1a72ff..091cb17d1a9b 100644
> >>> --- a/include/linux/bitops.h
> >>> +++ b/include/linux/bitops.h
> >>> @@ -11,7 +11,8 @@
> >>>  #define BIT_ULL_MASK(nr)     (1ULL << ((nr) % BITS_PER_LONG_LONG))
> >>>  #define BIT_ULL_WORD(nr)     ((nr) / BITS_PER_LONG_LONG)
> >>>  #define BITS_PER_BYTE                8
> >>> -#define BITS_TO_LONGS(nr)    DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
> >>> +#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
> >>> +#define BITS_TO_LONGS(nr)    DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
> >>>  #endif
> >>>  
> >>>  /*
> >>
> >> doesn't <linux/net_dim.h> need to #include <linux/bitops.h> ?
> > 
> > It already has to in order to obtain BITS_PER_BYTE. Just doesn't do so
> > directly.
> 
> Right.  and does that work on all $ARCHes?

It's a pre-existing dependency in the header, net_dim.h cannot
compile unless BITS_PER_BYTE is defined i.e. bitops.h is included.
The patch does not affect that.
-Chris

Re: [PATCH] bitops: Introduce BITS_PER_TYPE

[Randy Dunlap]

On 07/06/18 11:00, Chris Wilson wrote:
> Quoting Randy Dunlap (2018-07-06 18:55:57)
>> On 07/06/18 10:51, Chris Wilson wrote:
>>> Quoting Randy Dunlap (2018-07-06 18:48:55)
>>>>
>>>> On 07/06/18 02:44, Chris Wilson wrote:
>>>>> net_dim.h has a rather useful extension to BITS_PER_BYTE to compute the
>>>>> number of bits in a type (BITS_PER_BYTE * sizeof(T)), so promote the
>>>>> macro to bitops.h, alongside BITS_PER_BYTE, for wider usage.
>>>>>
>>>>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>>>>> Cc: Jani Nikula <jani.nikula@linux.intel.com>
>>>>> Cc: Andy Gospodarek <gospo@broadcom.com>
>>>>> Cc: David S. Miller <davem@davemloft.net>
>>>>> Cc: Thomas Gleixner <tglx@linutronix.de>
>>>>> Cc: Andrew Morton <akpm@linux-foundation.org>
>>>>> Cc: Ingo Molnar <mingo@kernel.org>
>>>>> ---
>>>>>  include/linux/bitops.h  | 3 ++-
>>>>>  include/linux/net_dim.h | 1 -
>>>>>  2 files changed, 2 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/include/linux/bitops.h b/include/linux/bitops.h
>>>>> index 4cac4e1a72ff..091cb17d1a9b 100644
>>>>> --- a/include/linux/bitops.h
>>>>> +++ b/include/linux/bitops.h
>>>>> @@ -11,7 +11,8 @@
>>>>>  #define BIT_ULL_MASK(nr)     (1ULL << ((nr) % BITS_PER_LONG_LONG))
>>>>>  #define BIT_ULL_WORD(nr)     ((nr) / BITS_PER_LONG_LONG)
>>>>>  #define BITS_PER_BYTE                8
>>>>> -#define BITS_TO_LONGS(nr)    DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
>>>>> +#define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE)
>>>>> +#define BITS_TO_LONGS(nr)    DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
>>>>>  #endif
>>>>>  
>>>>>  /*
>>>>
>>>> doesn't <linux/net_dim.h> need to #include <linux/bitops.h> ?
>>>
>>> It already has to in order to obtain BITS_PER_BYTE. Just doesn't do so
>>> directly.
>>
>> Right.  and does that work on all $ARCHes?
> 
> It's a pre-existing dependency in the header, net_dim.h cannot
> compile unless BITS_PER_BYTE is defined i.e. bitops.h is included.
> The patch does not affect that.

Yes, I see.  net_dim.h should have #included bits.h and/or bitops.h previously.

thanks,
-- 
~Randy

Re: [PATCH] bitops: Introduce BITS_PER_TYPE

[Andrew Morton]

On Fri,  6 Jul 2018 10:44:58 +0100 Chris Wilson <chris@chris-wilson.co.uk> wrote:

> net_dim.h has a rather useful extension to BITS_PER_BYTE to compute the
> number of bits in a type (BITS_PER_BYTE * sizeof(T)), so promote the
> macro to bitops.h, alongside BITS_PER_BYTE, for wider usage.

A bit of grepping shows that there's quite a lot of code which does
sizeof(blah)*BITS_PER_BYTE.  Fun newbie project.