On Wed, May 20, 2020 at 02:05:19PM +0200, Christian König wrote:
> Am 20.05.20 um 14:00 schrieb Dan Carpenter:
> > This loop in the error handling code should start a "i - 1" and end at
> > "i == 0". Currently it starts a "i" and ends at "i == 1". The result
> > is that it removes one attribute that wasn't created yet, and leaks the
> > zeroeth attribute.
> >
> > Fixes: 4e01847c38f7 ("drm/amdgpu: optimize amdgpu device attribute code")
> > Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > ---
> > drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
> > index b75362bf0742..ee4a8e44fbeb 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
> > @@ -1931,7 +1931,7 @@ static int amdgpu_device_attr_create_groups(struct amdgpu_device *adev,
> > uint32_t mask)
> > {
> > int ret = 0;
> > - uint32_t i = 0;
> > + int i;
> > for (i = 0; i < counts; i++) {
> > ret = amdgpu_device_attr_create(adev, &attrs[i], mask);
> > @@ -1942,9 +1942,8 @@ static int amdgpu_device_attr_create_groups(struct amdgpu_device *adev,
> > return 0;
> > failed:
> > - for (; i > 0; i--) {
> > + while (--i >= 0)
>
> As far as I know the common idiom for this is while (i--) which even works
> without changing the type of i to signed.
It's about 50/50, one way or the other. To me --i >= 0 seems far more
readable.
I've been trying to figure out which tool tells people to make iterators
unsigned so I can help them avoid it. :/ I understand how in theory
iterators could go above INT_MAX but if we're going above INT_MAX then
probably we should use a 64 bit type. There are very few times where 2
billion iterations is not enough but in those situations probably 4
billion is not enough either. So unsigned int iterators never or seldom
solve real life bugs but they regularly cause them.
regards,
dan carpenter
