From: Bartosz Golaszewski <[email protected]>
We now have devm_krealloc() in the kernel Use it indstead of calling
kfree() and kcalloc() separately.
Signed-off-by: Bartosz Golaszewski <[email protected]>
---
drivers/iio/adc/xilinx-xadc-core.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c
index 8494eb424b33..b516280ccbd4 100644
--- a/drivers/iio/adc/xilinx-xadc-core.c
+++ b/drivers/iio/adc/xilinx-xadc-core.c
@@ -589,8 +589,9 @@ static int xadc_update_scan_mode(struct iio_dev *indio_dev,
n = bitmap_weight(mask, indio_dev->masklength);
- kfree(xadc->data);
- xadc->data = kcalloc(n, sizeof(*xadc->data), GFP_KERNEL);
+ xadc->data = devm_krealloc(indio_dev->dev.parent, xadc->data,
+ n * sizeof(*xadc->data),
+ GFP_KERNEL | __GFP_ZERO);
if (!xadc->data)
return -ENOMEM;
@@ -1372,7 +1373,6 @@ static int xadc_remove(struct platform_device *pdev)
free_irq(xadc->irq, indio_dev);
cancel_delayed_work_sync(&xadc->zynq_unmask_work);
clk_disable_unprepare(xadc->clk);
- kfree(xadc->data);
return 0;
}
--
2.29.1
On Mon, Oct 26, 2020 at 4:03 PM Bartosz Golaszewski <[email protected]> wrote:
>
> From: Bartosz Golaszewski <[email protected]>
>
> We now have devm_krealloc() in the kernel Use it indstead of calling
> kfree() and kcalloc() separately.
Which is completely lawful when size > previous_size (I mean, the
additional patch you sent previously seems not related to this).
> - kfree(xadc->data);
> - xadc->data = kcalloc(n, sizeof(*xadc->data), GFP_KERNEL);
> + xadc->data = devm_krealloc(indio_dev->dev.parent, xadc->data,
> + n * sizeof(*xadc->data),
I think you need to use something from overflow.h instead of explicit
multiplication here.
> + GFP_KERNEL | __GFP_ZERO);
--
With Best Regards,
Andy Shevchenko
On Tue, Oct 27, 2020 at 10:33 AM Andy Shevchenko
<[email protected]> wrote:
>
> On Mon, Oct 26, 2020 at 4:03 PM Bartosz Golaszewski <[email protected]> wrote:
> >
> > From: Bartosz Golaszewski <[email protected]>
> >
> > We now have devm_krealloc() in the kernel Use it indstead of calling
> > kfree() and kcalloc() separately.
>
> Which is completely lawful when size > previous_size (I mean, the
> additional patch you sent previously seems not related to this).
>
Sure but devm_krealloc() is cleaner and adds the benefit of resource management.
> > - kfree(xadc->data);
> > - xadc->data = kcalloc(n, sizeof(*xadc->data), GFP_KERNEL);
> > + xadc->data = devm_krealloc(indio_dev->dev.parent, xadc->data,
> > + n * sizeof(*xadc->data),
>
> I think you need to use something from overflow.h instead of explicit
> multiplication here.
>
Or maybe add devm_krealloc_array() which would perform the checks
behind the scenes?
> > + GFP_KERNEL | __GFP_ZERO);
>
> --
> With Best Regards,
> Andy Shevchenko
Bartosz
On Tue, Oct 27, 2020 at 12:04 PM Bartosz Golaszewski <[email protected]> wrote:
> On Tue, Oct 27, 2020 at 10:33 AM Andy Shevchenko
> <[email protected]> wrote:
> >
> > On Mon, Oct 26, 2020 at 4:03 PM Bartosz Golaszewski <[email protected]> wrote:
> > >
> > > From: Bartosz Golaszewski <[email protected]>
> > >
> > > We now have devm_krealloc() in the kernel Use it indstead of calling
> > > kfree() and kcalloc() separately.
> >
> > Which is completely lawful when size > previous_size (I mean, the
> > additional patch you sent previously seems not related to this).
> >
>
> Sure but devm_krealloc() is cleaner and adds the benefit of resource management.
I meant devm_krealloc(). It should work in this case without your
additional "fix" patch.
> > > - kfree(xadc->data);
> > > - xadc->data = kcalloc(n, sizeof(*xadc->data), GFP_KERNEL);
> > > + xadc->data = devm_krealloc(indio_dev->dev.parent, xadc->data,
> > > + n * sizeof(*xadc->data),
> >
> > I think you need to use something from overflow.h instead of explicit
> > multiplication here.
> >
>
> Or maybe add devm_krealloc_array() which would perform the checks
> behind the scenes?
Maybe. But what to do in the cases when you have struct with flexible
arrays, like
struct foo {
...
type bar[];
};
?
And you do kzalloc(sizeof(foo)) followed by krealloc(). The above name
(krealloc_array) may be a bit ambiguous.
> > > + GFP_KERNEL | __GFP_ZERO);
--
With Best Regards,
Andy Shevchenko
On Tue, Oct 27, 2020 at 11:29 AM Andy Shevchenko
<[email protected]> wrote:
>
> On Tue, Oct 27, 2020 at 12:04 PM Bartosz Golaszewski <[email protected]> wrote:
> > On Tue, Oct 27, 2020 at 10:33 AM Andy Shevchenko
> > <[email protected]> wrote:
> > >
> > > On Mon, Oct 26, 2020 at 4:03 PM Bartosz Golaszewski <[email protected]> wrote:
> > > >
> > > > From: Bartosz Golaszewski <[email protected]>
> > > >
> > > > We now have devm_krealloc() in the kernel Use it indstead of calling
> > > > kfree() and kcalloc() separately.
> > >
> > > Which is completely lawful when size > previous_size (I mean, the
> > > additional patch you sent previously seems not related to this).
> > >
> >
> > Sure but devm_krealloc() is cleaner and adds the benefit of resource management.
>
> I meant devm_krealloc(). It should work in this case without your
> additional "fix" patch.
>
I know, this is why I sent the fix separately. The fix is still
correct on its own.
> > > > - kfree(xadc->data);
> > > > - xadc->data = kcalloc(n, sizeof(*xadc->data), GFP_KERNEL);
> > > > + xadc->data = devm_krealloc(indio_dev->dev.parent, xadc->data,
> > > > + n * sizeof(*xadc->data),
> > >
> > > I think you need to use something from overflow.h instead of explicit
> > > multiplication here.
> > >
> >
> > Or maybe add devm_krealloc_array() which would perform the checks
> > behind the scenes?
>
> Maybe. But what to do in the cases when you have struct with flexible
> arrays, like
> struct foo {
> ...
> type bar[];
> };
>
> ?
Just use regular devm_krealloc() with struct_size()?
>
> And you do kzalloc(sizeof(foo)) followed by krealloc(). The above name
> (krealloc_array) may be a bit ambiguous.
But devm_krealloc_array() would only be useful for memory allocated by
kmalloc_array() or kcalloc(). I don't see what's your point.
Bartosz
On Tue, Oct 27, 2020 at 12:40 PM Bartosz Golaszewski
<[email protected]> wrote:
> On Tue, Oct 27, 2020 at 11:29 AM Andy Shevchenko
> <[email protected]> wrote:
> > On Tue, Oct 27, 2020 at 12:04 PM Bartosz Golaszewski <[email protected]> wrote:
> > > On Tue, Oct 27, 2020 at 10:33 AM Andy Shevchenko
> > > <[email protected]> wrote:
...
> > I meant devm_krealloc(). It should work in this case without your
> > additional "fix" patch.
> I know, this is why I sent the fix separately. The fix is still
> correct on its own.
My point is it's not needed. At all.
It will actually make a regression. But this is for discussion in that thread.
...
> > > Or maybe add devm_krealloc_array() which would perform the checks
> > > behind the scenes?
> >
> > Maybe. But what to do in the cases when you have struct with flexible
> > arrays, like
> > struct foo {
> > ...
> > type bar[];
> > };
> >
> > ?
>
> Just use regular devm_krealloc() with struct_size()?
>
> >
> > And you do kzalloc(sizeof(foo)) followed by krealloc(). The above name
> > (krealloc_array) may be a bit ambiguous.
>
> But devm_krealloc_array() would only be useful for memory allocated by
> kmalloc_array() or kcalloc(). I don't see what's your point.
Naming ambiguity.
Here I'm not against it. If you think it's a good idea, go for it!
--
With Best Regards,
Andy Shevchenko