This will reduce parameter passing and enable using nbits as part
of future dynamic region parameter parsing.
Cc: Yury Norov <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Suggested-by: Yury Norov <[email protected]>
Signed-off-by: Paul Gortmaker <[email protected]>
---
lib/bitmap.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 75006c4036e9..162e2850c622 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -487,24 +487,24 @@ EXPORT_SYMBOL(bitmap_print_to_pagebuf);
/*
* Region 9-38:4/10 describes the following bitmap structure:
- * 0 9 12 18 38
- * .........****......****......****......
- * ^ ^ ^ ^
- * start off group_len end
+ * 0 9 12 18 38 N
+ * .........****......****......****..................
+ * ^ ^ ^ ^ ^
+ * start off group_len end nbits
*/
struct region {
unsigned int start;
unsigned int off;
unsigned int group_len;
unsigned int end;
+ unsigned int nbits;
};
-static int bitmap_set_region(const struct region *r,
- unsigned long *bitmap, int nbits)
+static int bitmap_set_region(const struct region *r, unsigned long *bitmap)
{
unsigned int start;
- if (r->end >= nbits)
+ if (r->end >= r->nbits)
return -ERANGE;
for (start = r->start; start <= r->end; start += r->group_len)
@@ -640,7 +640,8 @@ int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
struct region r;
long ret;
- bitmap_zero(maskp, nmaskbits);
+ r.nbits = nmaskbits;
+ bitmap_zero(maskp, r.nbits);
while (buf) {
buf = bitmap_find_region(buf);
@@ -655,7 +656,7 @@ int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
if (ret)
return ret;
- ret = bitmap_set_region(&r, maskp, nmaskbits);
+ ret = bitmap_set_region(&r, maskp);
if (ret)
return ret;
}
--
2.17.1
On Tue, Jan 26, 2021 at 12:11:36PM -0500, Paul Gortmaker wrote:
> This will reduce parameter passing and enable using nbits as part
> of future dynamic region parameter parsing.
One nit below, nevertheless
Reviewed-by: Andy Shevchenko <[email protected]>
> Cc: Yury Norov <[email protected]>
> Cc: Rasmus Villemoes <[email protected]>
> Cc: Andy Shevchenko <[email protected]>
> Suggested-by: Yury Norov <[email protected]>
> Signed-off-by: Paul Gortmaker <[email protected]>
> ---
> lib/bitmap.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/lib/bitmap.c b/lib/bitmap.c
> index 75006c4036e9..162e2850c622 100644
> --- a/lib/bitmap.c
> +++ b/lib/bitmap.c
> @@ -487,24 +487,24 @@ EXPORT_SYMBOL(bitmap_print_to_pagebuf);
>
> /*
> * Region 9-38:4/10 describes the following bitmap structure:
> - * 0 9 12 18 38
> - * .........****......****......****......
> - * ^ ^ ^ ^
> - * start off group_len end
> + * 0 9 12 18 38 N
> + * .........****......****......****..................
> + * ^ ^ ^ ^ ^
> + * start off group_len end nbits
> */
> struct region {
> unsigned int start;
> unsigned int off;
> unsigned int group_len;
> unsigned int end;
> + unsigned int nbits;
> };
>
> -static int bitmap_set_region(const struct region *r,
> - unsigned long *bitmap, int nbits)
> +static int bitmap_set_region(const struct region *r, unsigned long *bitmap)
> {
> unsigned int start;
>
> - if (r->end >= nbits)
> + if (r->end >= r->nbits)
> return -ERANGE;
>
> for (start = r->start; start <= r->end; start += r->group_len)
> @@ -640,7 +640,8 @@ int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
> struct region r;
> long ret;
>
> - bitmap_zero(maskp, nmaskbits);
> + r.nbits = nmaskbits;
> + bitmap_zero(maskp, r.nbits);
This sounds not right from style perspective.
You have completely uninitialized r on stack, then you assign only one value
for immediate use here and...
> while (buf) {
> buf = bitmap_find_region(buf);
> @@ -655,7 +656,7 @@ int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
> if (ret)
> return ret;
>
> - ret = bitmap_set_region(&r, maskp, nmaskbits);
> + ret = bitmap_set_region(&r, maskp);
...hiding this fact here. Which I would expect that &r may be rewritten here.
I would leave these unchanged and simple assign the value in
bitmap_set_region().
> if (ret)
> return ret;
> }
> --
> 2.17.1
>
--
With Best Regards,
Andy Shevchenko
On Tue, Jan 26, 2021 at 11:16:25PM +0200, Andy Shevchenko wrote:
> On Tue, Jan 26, 2021 at 12:11:36PM -0500, Paul Gortmaker wrote:
> > This will reduce parameter passing and enable using nbits as part
> > of future dynamic region parameter parsing.
...
> > struct region r;
> > long ret;
> >
> > - bitmap_zero(maskp, nmaskbits);
> > + r.nbits = nmaskbits;
Alternatively (though I personally don't prefer it) you can clarify in the
definition block the initial values.
struct region r = { .nbist = nmaskbits };
> > + bitmap_zero(maskp, r.nbits);
>
> This sounds not right from style perspective.
> You have completely uninitialized r on stack, then you assign only one value
> for immediate use here and...
>
> > while (buf) {
> > buf = bitmap_find_region(buf);
> > @@ -655,7 +656,7 @@ int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
> > if (ret)
> > return ret;
> >
> > - ret = bitmap_set_region(&r, maskp, nmaskbits);
> > + ret = bitmap_set_region(&r, maskp);
>
> ...hiding this fact here. Which I would expect that &r may be rewritten here.
>
> I would leave these unchanged and simple assign the value in
> bitmap_set_region().
--
With Best Regards,
Andy Shevchenko
On Tue, Jan 26, 2021 at 9:12 AM Paul Gortmaker
<[email protected]> wrote:
>
> This will reduce parameter passing and enable using nbits as part
> of future dynamic region parameter parsing.
>
> Cc: Yury Norov <[email protected]>
> Cc: Rasmus Villemoes <[email protected]>
> Cc: Andy Shevchenko <[email protected]>
> Suggested-by: Yury Norov <[email protected]>
> Signed-off-by: Paul Gortmaker <[email protected]>
> ---
> lib/bitmap.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/lib/bitmap.c b/lib/bitmap.c
> index 75006c4036e9..162e2850c622 100644
> --- a/lib/bitmap.c
> +++ b/lib/bitmap.c
> @@ -487,24 +487,24 @@ EXPORT_SYMBOL(bitmap_print_to_pagebuf);
>
> /*
> * Region 9-38:4/10 describes the following bitmap structure:
> - * 0 9 12 18 38
> - * .........****......****......****......
> - * ^ ^ ^ ^
> - * start off group_len end
> + * 0 9 12 18 38 N
> + * .........****......****......****..................
> + * ^ ^ ^ ^ ^
> + * start off group_len end nbits
> */
> struct region {
> unsigned int start;
> unsigned int off;
> unsigned int group_len;
> unsigned int end;
> + unsigned int nbits;
> };
>
> -static int bitmap_set_region(const struct region *r,
> - unsigned long *bitmap, int nbits)
> +static int bitmap_set_region(const struct region *r, unsigned long *bitmap)
> {
> unsigned int start;
>
> - if (r->end >= nbits)
> + if (r->end >= r->nbits)
> return -ERANGE;
>
> for (start = r->start; start <= r->end; start += r->group_len)
> @@ -640,7 +640,8 @@ int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
> struct region r;
> long ret;
>
> - bitmap_zero(maskp, nmaskbits);
> + r.nbits = nmaskbits;
> + bitmap_zero(maskp, r.nbits);
>
> while (buf) {
> buf = bitmap_find_region(buf);
> @@ -655,7 +656,7 @@ int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
> if (ret)
> return ret;
>
> - ret = bitmap_set_region(&r, maskp, nmaskbits);
> + ret = bitmap_set_region(&r, maskp);
> if (ret)
> return ret;
> }
> --
> 2.17.1
Acked-by: Yury Norov <[email protected]>
[Re: [PATCH 3/8] lib: bitmap: fold nbits into region struct] On 26/01/2021 (Tue 23:16) Andy Shevchenko wrote:
> On Tue, Jan 26, 2021 at 12:11:36PM -0500, Paul Gortmaker wrote:
> > This will reduce parameter passing and enable using nbits as part
> > of future dynamic region parameter parsing.
>
> One nit below, nevertheless
> Reviewed-by: Andy Shevchenko <[email protected]>
>
> > Cc: Yury Norov <[email protected]>
> > Cc: Rasmus Villemoes <[email protected]>
> > Cc: Andy Shevchenko <[email protected]>
> > Suggested-by: Yury Norov <[email protected]>
> > Signed-off-by: Paul Gortmaker <[email protected]>
> > ---
> > lib/bitmap.c | 19 ++++++++++---------
> > 1 file changed, 10 insertions(+), 9 deletions(-)
> >
> > diff --git a/lib/bitmap.c b/lib/bitmap.c
> > index 75006c4036e9..162e2850c622 100644
> > --- a/lib/bitmap.c
> > +++ b/lib/bitmap.c
> > @@ -487,24 +487,24 @@ EXPORT_SYMBOL(bitmap_print_to_pagebuf);
> >
> > /*
> > * Region 9-38:4/10 describes the following bitmap structure:
> > - * 0 9 12 18 38
> > - * .........****......****......****......
> > - * ^ ^ ^ ^
> > - * start off group_len end
> > + * 0 9 12 18 38 N
> > + * .........****......****......****..................
> > + * ^ ^ ^ ^ ^
> > + * start off group_len end nbits
> > */
> > struct region {
> > unsigned int start;
> > unsigned int off;
> > unsigned int group_len;
> > unsigned int end;
> > + unsigned int nbits;
> > };
> >
> > -static int bitmap_set_region(const struct region *r,
> > - unsigned long *bitmap, int nbits)
> > +static int bitmap_set_region(const struct region *r, unsigned long *bitmap)
> > {
> > unsigned int start;
> >
> > - if (r->end >= nbits)
> > + if (r->end >= r->nbits)
> > return -ERANGE;
> >
> > for (start = r->start; start <= r->end; start += r->group_len)
> > @@ -640,7 +640,8 @@ int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
> > struct region r;
> > long ret;
> >
> > - bitmap_zero(maskp, nmaskbits);
> > + r.nbits = nmaskbits;
>
> > + bitmap_zero(maskp, r.nbits);
>
> This sounds not right from style perspective.
> You have completely uninitialized r on stack, then you assign only one value
> for immediate use here and...
So, this change was added because Yury suggested that I "..store
nmaskbits in the struct region, and avoid passing nmaskbits as a
parameter."
To which I originally noted "I considered that and went with the param
so as to not open the door to someone possibly using an uninitialized
struct value later."
https://lore.kernel.org/lkml/[email protected]/
Looking back, I had a similar thought as to yours, it seems...
I am also thinking more and more that nbits doesn't belong in the
region anyway - yes, a region gets validated against a specific nbits
eventually, but it doesn't need an nbits field to be a complete
specification. The region "0-3" is a complete specification for "the
1st four cores" and is as valid on a 4 core machine as it is on a 64 core
machine -- a validation we do when we deploy the region on that machine.
I will set this change aside and get the nbits value to getnum() another
way, and leave the region struct as it was -- without a nbits field.
This will also resolve having the macro handling of region that you were
not really liking.
Paul.
--
> > while (buf) {
> > buf = bitmap_find_region(buf);
> > @@ -655,7 +656,7 @@ int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
> > if (ret)
> > return ret;
> >
> > - ret = bitmap_set_region(&r, maskp, nmaskbits);
> > + ret = bitmap_set_region(&r, maskp);
>
> ...hiding this fact here. Which I would expect that &r may be rewritten here.
>
> I would leave these unchanged and simple assign the value in
> bitmap_set_region().
>
> > if (ret)
> > return ret;
> > }
> > --
> > 2.17.1
> >
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
On Wed, Jan 27, 2021 at 12:02 AM Paul Gortmaker
<[email protected]> wrote:
>
> [Re: [PATCH 3/8] lib: bitmap: fold nbits into region struct] On 26/01/2021 (Tue 23:16) Andy Shevchenko wrote:
>
> > On Tue, Jan 26, 2021 at 12:11:36PM -0500, Paul Gortmaker wrote:
> > > This will reduce parameter passing and enable using nbits as part
> > > of future dynamic region parameter parsing.
> >
> > One nit below, nevertheless
> > Reviewed-by: Andy Shevchenko <[email protected]>
> >
> > > Cc: Yury Norov <[email protected]>
> > > Cc: Rasmus Villemoes <[email protected]>
> > > Cc: Andy Shevchenko <[email protected]>
> > > Suggested-by: Yury Norov <[email protected]>
> > > Signed-off-by: Paul Gortmaker <[email protected]>
> > > ---
> > > lib/bitmap.c | 19 ++++++++++---------
> > > 1 file changed, 10 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/lib/bitmap.c b/lib/bitmap.c
> > > index 75006c4036e9..162e2850c622 100644
> > > --- a/lib/bitmap.c
> > > +++ b/lib/bitmap.c
> > > @@ -487,24 +487,24 @@ EXPORT_SYMBOL(bitmap_print_to_pagebuf);
> > >
> > > /*
> > > * Region 9-38:4/10 describes the following bitmap structure:
> > > - * 0 9 12 18 38
> > > - * .........****......****......****......
> > > - * ^ ^ ^ ^
> > > - * start off group_len end
> > > + * 0 9 12 18 38 N
> > > + * .........****......****......****..................
> > > + * ^ ^ ^ ^ ^
> > > + * start off group_len end nbits
> > > */
> > > struct region {
> > > unsigned int start;
> > > unsigned int off;
> > > unsigned int group_len;
> > > unsigned int end;
> > > + unsigned int nbits;
> > > };
> > >
> > > -static int bitmap_set_region(const struct region *r,
> > > - unsigned long *bitmap, int nbits)
> > > +static int bitmap_set_region(const struct region *r, unsigned long *bitmap)
> > > {
> > > unsigned int start;
> > >
> > > - if (r->end >= nbits)
> > > + if (r->end >= r->nbits)
> > > return -ERANGE;
> > >
> > > for (start = r->start; start <= r->end; start += r->group_len)
> > > @@ -640,7 +640,8 @@ int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
> > > struct region r;
> > > long ret;
> > >
> > > - bitmap_zero(maskp, nmaskbits);
> > > + r.nbits = nmaskbits;
> >
> > > + bitmap_zero(maskp, r.nbits);
> >
> > This sounds not right from style perspective.
> > You have completely uninitialized r on stack, then you assign only one value
> > for immediate use here and...
>
> So, this change was added because Yury suggested that I "..store
> nmaskbits in the struct region, and avoid passing nmaskbits as a
> parameter."
>
> To which I originally noted "I considered that and went with the param
> so as to not open the door to someone possibly using an uninitialized
> struct value later."
struct region is purely internal structure. It's declared on stack and filled
field-by-field using helpers. 'Someone' misusing the structure doesn't exist
because the structure doesn't exist out of the scope.
> https://lore.kernel.org/lkml/[email protected]/
>
> Looking back, I had a similar thought as to yours, it seems...
>
> I am also thinking more and more that nbits doesn't belong in the
> region anyway - yes, a region gets validated against a specific nbits
> eventually, but it doesn't need an nbits field to be a complete
> specification. The region "0-3" is a complete specification for "the
> 1st four cores" and is as valid on a 4 core machine as it is on a 64 core
> machine -- a validation we do when we deploy the region on that machine.
>
> I will set this change aside and get the nbits value to getnum() another
> way, and leave the region struct as it was -- without a nbits field.
>
> This will also resolve having the macro handling of region that you were
> not really liking.
>
> Paul.
Region is a convenient structure. Adding nbits into it helps to remove
validation
logic from bitmap_set_region(), so it's worth doing this.
Can you please have it unchanged?
Thanks,
Yury
On Thu, Jan 28, 2021 at 2:52 AM Yury Norov <[email protected]> wrote:
> On Wed, Jan 27, 2021 at 12:02 AM Paul Gortmaker
> <[email protected]> wrote:
...
> > So, this change was added because Yury suggested that I "..store
> > nmaskbits in the struct region, and avoid passing nmaskbits as a
> > parameter."
> >
> > To which I originally noted "I considered that and went with the param
> > so as to not open the door to someone possibly using an uninitialized
> > struct value later."
>
> struct region is purely internal structure. It's declared on stack and filled
> field-by-field using helpers. 'Someone' misusing the structure doesn't exist
> because the structure doesn't exist out of the scope.
>
> > https://lore.kernel.org/lkml/[email protected]/
> >
> > Looking back, I had a similar thought as to yours, it seems...
> >
> > I am also thinking more and more that nbits doesn't belong in the
> > region anyway - yes, a region gets validated against a specific nbits
> > eventually, but it doesn't need an nbits field to be a complete
> > specification. The region "0-3" is a complete specification for "the
> > 1st four cores" and is as valid on a 4 core machine as it is on a 64 core
> > machine -- a validation we do when we deploy the region on that machine.
> >
> > I will set this change aside and get the nbits value to getnum() another
> > way, and leave the region struct as it was -- without a nbits field.
> >
> > This will also resolve having the macro handling of region that you were
> > not really liking.
> Region is a convenient structure. Adding nbits into it helps to remove
> validation
> logic from bitmap_set_region(), so it's worth doing this.
>
> Can you please have it unchanged?
I have a compromise proposal here, i.e. why not to create a wrapper
structure like
struct bitmap_region {
unsigned int nbits;
struct region r;
};
?
At least it will solve my concern and still be a local structure on
the stack without adding new parameters to called functions.
--
With Best Regards,
Andy Shevchenko