The tmp[] member of the gpiochip_fwd structure is used to store both the
temporary values bitmap and the desc pointers for operations on multiple
GPIOs. As both are arrays with sizes unknown at compile-time, accessing
them requires offset calculations, which are currently duplicated in
gpio_fwd_get_multiple() and gpio_fwd_set_multiple().
Introduce (a) accessors for both arrays and (b) a macro to calculate the
needed storage size. This confines the layout of the tmp[] member into
a single spot, to ease maintenance.
Signed-off-by: Geert Uytterhoeven <[email protected]>
---
drivers/gpio/gpio-aggregator.c | 25 +++++++++++--------------
1 file changed, 11 insertions(+), 14 deletions(-)
diff --git a/drivers/gpio/gpio-aggregator.c b/drivers/gpio/gpio-aggregator.c
index 2ff867d2a3630d3b..869dc952cf45218b 100644
--- a/drivers/gpio/gpio-aggregator.c
+++ b/drivers/gpio/gpio-aggregator.c
@@ -247,6 +247,11 @@ struct gpiochip_fwd {
unsigned long tmp[]; /* values and descs for multiple ops */
};
+#define fwd_tmp_values(fwd) &(fwd)->tmp[0]
+#define fwd_tmp_descs(fwd) (void *)&(fwd)->tmp[BITS_TO_LONGS((fwd)->chip.ngpio)]
+
+#define fwd_tmp_size(ngpios) (BITS_TO_LONGS((ngpios)) + (ngpios))
+
static int gpio_fwd_get_direction(struct gpio_chip *chip, unsigned int offset)
{
struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
@@ -279,15 +284,11 @@ static int gpio_fwd_get(struct gpio_chip *chip, unsigned int offset)
static int gpio_fwd_get_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
unsigned long *bits)
{
- struct gpio_desc **descs;
- unsigned long *values;
+ struct gpio_desc **descs = fwd_tmp_descs(fwd);
+ unsigned long *values = fwd_tmp_values(fwd);
unsigned int i, j = 0;
int error;
- /* Both values bitmap and desc pointers are stored in tmp[] */
- values = &fwd->tmp[0];
- descs = (void *)&fwd->tmp[BITS_TO_LONGS(fwd->chip.ngpio)];
-
bitmap_clear(values, 0, fwd->chip.ngpio);
for_each_set_bit(i, mask, fwd->chip.ngpio)
descs[j++] = fwd->descs[i];
@@ -333,14 +334,10 @@ static void gpio_fwd_set(struct gpio_chip *chip, unsigned int offset, int value)
static void gpio_fwd_set_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
unsigned long *bits)
{
- struct gpio_desc **descs;
- unsigned long *values;
+ struct gpio_desc **descs = fwd_tmp_descs(fwd);
+ unsigned long *values = fwd_tmp_values(fwd);
unsigned int i, j = 0;
- /* Both values bitmap and desc pointers are stored in tmp[] */
- values = &fwd->tmp[0];
- descs = (void *)&fwd->tmp[BITS_TO_LONGS(fwd->chip.ngpio)];
-
for_each_set_bit(i, mask, fwd->chip.ngpio) {
__assign_bit(j, values, test_bit(i, bits));
descs[j++] = fwd->descs[i];
@@ -405,8 +402,8 @@ static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev,
unsigned int i;
int error;
- fwd = devm_kzalloc(dev, struct_size(fwd, tmp,
- BITS_TO_LONGS(ngpios) + ngpios), GFP_KERNEL);
+ fwd = devm_kzalloc(dev, struct_size(fwd, tmp, fwd_tmp_size(ngpios)),
+ GFP_KERNEL);
if (!fwd)
return ERR_PTR(-ENOMEM);
--
2.25.1
Hi Andy,
On Mon, Oct 4, 2021 at 3:23 PM Andy Shevchenko
<[email protected]> wrote:
> On Mon, Oct 4, 2021 at 3:47 PM Geert Uytterhoeven
> <[email protected]> wrote:
> > The tmp[] member of the gpiochip_fwd structure is used to store both the
> > temporary values bitmap and the desc pointers for operations on multiple
> > GPIOs. As both are arrays with sizes unknown at compile-time, accessing
> > them requires offset calculations, which are currently duplicated in
> > gpio_fwd_get_multiple() and gpio_fwd_set_multiple().
> >
> > Introduce (a) accessors for both arrays and (b) a macro to calculate the
> > needed storage size. This confines the layout of the tmp[] member into
> > a single spot, to ease maintenance.
>
> ...
>
> > +#define fwd_tmp_descs(fwd) (void *)&(fwd)->tmp[BITS_TO_LONGS((fwd)->chip.ngpio)]
> > +
> > +#define fwd_tmp_size(ngpios) (BITS_TO_LONGS((ngpios)) + (ngpios))
>
> ...
>
> > - fwd = devm_kzalloc(dev, struct_size(fwd, tmp,
> > - BITS_TO_LONGS(ngpios) + ngpios), GFP_KERNEL);
> > + fwd = devm_kzalloc(dev, struct_size(fwd, tmp, fwd_tmp_size(ngpios)),
> > + GFP_KERNEL);
>
> Shouldn't we rather use devm_bitmap_zalloc() / bitmap_free()?
That's not sufficient: the bitmap is only one part. There are one
fixed-size and two variable-size objects to allocate.
Yes, they can be allocated separately, at the expense of more
allocations, and more data (pointers) to allocate to keep track of
all those objects.
>
> > if (!fwd)
> > return ERR_PTR(-ENOMEM);
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
On Mon, Oct 4, 2021 at 3:47 PM Geert Uytterhoeven
<[email protected]> wrote:
>
> The tmp[] member of the gpiochip_fwd structure is used to store both the
> temporary values bitmap and the desc pointers for operations on multiple
> GPIOs. As both are arrays with sizes unknown at compile-time, accessing
> them requires offset calculations, which are currently duplicated in
> gpio_fwd_get_multiple() and gpio_fwd_set_multiple().
>
> Introduce (a) accessors for both arrays and (b) a macro to calculate the
> needed storage size. This confines the layout of the tmp[] member into
> a single spot, to ease maintenance.
...
> +#define fwd_tmp_descs(fwd) (void *)&(fwd)->tmp[BITS_TO_LONGS((fwd)->chip.ngpio)]
> +
> +#define fwd_tmp_size(ngpios) (BITS_TO_LONGS((ngpios)) + (ngpios))
...
> - fwd = devm_kzalloc(dev, struct_size(fwd, tmp,
> - BITS_TO_LONGS(ngpios) + ngpios), GFP_KERNEL);
> + fwd = devm_kzalloc(dev, struct_size(fwd, tmp, fwd_tmp_size(ngpios)),
> + GFP_KERNEL);
Shouldn't we rather use devm_bitmap_zalloc() / bitmap_free()?
> if (!fwd)
> return ERR_PTR(-ENOMEM);
--
With Best Regards,
Andy Shevchenko
On Mon, Oct 4, 2021 at 2:45 PM Geert Uytterhoeven
<[email protected]> wrote:
>
> The tmp[] member of the gpiochip_fwd structure is used to store both the
> temporary values bitmap and the desc pointers for operations on multiple
> GPIOs. As both are arrays with sizes unknown at compile-time, accessing
> them requires offset calculations, which are currently duplicated in
> gpio_fwd_get_multiple() and gpio_fwd_set_multiple().
>
> Introduce (a) accessors for both arrays and (b) a macro to calculate the
> needed storage size. This confines the layout of the tmp[] member into
> a single spot, to ease maintenance.
>
> Signed-off-by: Geert Uytterhoeven <[email protected]>
> ---
Applied, thanks!
Bart