lkml.org 
[lkml]   [2017]   [Feb]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [Outreachy kernel] [PATCH v2 2/7] staging: most: Using macro DIV_ROUND_UP


On Wed, 22 Feb 2017, SIMRAN SINGHAL wrote:

>
>
> On Wednesday, February 22, 2017 at 2:57:17 PM UTC+5:30, Julia Lawall wrote:
> > @@ -117,7 +118,7 @@ static int alloc_dbr(u16 size)
> >                  return DBR_SIZE; /* out of memory */
> >
> >          for (i = 0; i < DBR_MAP_SIZE; i++) {
> > -                u32 const blocks = (size + DBR_BLOCK_SIZE -
> 1) / DBR_BLOCK_SIZE;
> > +                u32 const blocks = DIV_ROUND_UP(size,
> DBR_BLOCK_SIZE);
> >                  u32 mask = ~((~(u32)0) << blocks);
>
> Totally unrelated to DIV_ROUND_UP, would this code be a
> candidate for
> GENMASK?
>
>  
> Not sure, what you are trying to say.

There was a discussion on the list recently about GENMASK, which allows to
create a mask containing a sequence of 1s, like 000011110000. It looks
like that is what is being done here, because ~0 is 11111111 and then it
ie being shifted left and all the bits inverted. But Joe had another
suggestion. One could double check that his suggestion gives the right
result.

julia

>
>  
>
> julia
>
> >
> >                  do {
> > @@ -137,7 +138,7 @@ static int alloc_dbr(u16 size)
> >  static void free_dbr(int offs, int size)
> >  {
> >          int block_idx = offs / DBR_BLOCK_SIZE;
> > -        u32 const blocks = (size + DBR_BLOCK_SIZE - 1) /
> DBR_BLOCK_SIZE;
> > +        u32 const blocks = DIV_ROUND_UP(size,
> DBR_BLOCK_SIZE);
> >          u32 mask = ~((~(u32)0) << blocks);
> >
> >          mask <<= block_idx % 32;
> > --
> > 2.7.4
> >
> > --
> > You received this message because you are subscribed to the
> Google Groups "outreachy-kernel" group.
> > To unsubscribe from this group and stop receiving emails from
> it, send an email to outreachy-kern...@googlegroups.com.
> > To post to this group, send email to
> outreach...@googlegroups.com.
> > To view this discussion on the web visithttps://groups.google.com/d/msgid/outreachy-kernel/20170222091015.GA11058%4
> 0singhal-Inspiron-5558.
> > For more options, visit https://groups.google.com/d/optout.
> >
>
> --
> You received this message because you are subscribed to the Google Groups
> "outreachy-kernel" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to outreachy-kernel+unsubscribe@googlegroups.com.
> To post to this group, send email to outreachy-kernel@googlegroups.com.
> To view this discussion on the web visithttps://groups.google.com/d/msgid/outreachy-kernel/d1716b00-a408-4f3c-8c17-
> 04a70acca4dd%40googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.
>
>
\
 
 \ /
  Last update: 2017-02-22 12:38    [W:0.052 / U:0.256 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site