On Tue, 2 Apr 2024 18:52:12 +0530
Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx> wrote:
> Hello Boris,
>
> On 02/04/24 18:03, Boris Brezillon wrote:
> > Hello Harshit,
> >
> > On Tue, 2 Apr 2024 03:33:58 -0700
> > Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx> wrote:
> >
> >> panthor_vm_get_heap_pool() returns ERR_PTR on failure.
> >>
> >> Fixes: 4bdca1150792 ("drm/panthor: Add the driver frontend block")
> >> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx>
> >> ---
> >> This is spotted by smatch and the patch is only compile tested
> >> ---
> >> drivers/gpu/drm/panthor/panthor_drv.c | 4 ++--
> >> 1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
> >> index 11b3ccd58f85..050b905b0453 100644
> >> --- a/drivers/gpu/drm/panthor/panthor_drv.c
> >> +++ b/drivers/gpu/drm/panthor/panthor_drv.c
> >> @@ -1090,8 +1090,8 @@ static int panthor_ioctl_tiler_heap_destroy(struct drm_device *ddev, void *data,
> >> return -EINVAL;
> >>
> >> pool = panthor_vm_get_heap_pool(vm, false);
> >> - if (!pool) {
> >> - ret = -EINVAL;
> >> + if (IS_ERR(pool)) {
> >> + ret = PTR_ERR(pool);
> >
> > Actually, panthor_vm_get_heap_pool() will return NULL if there's no
> > heap pool attached to this VM and create=false, so this was correct.
> > This being said, I'm fine making that consistent by returning
> > ERR_PTR(-ENOENT) instead of NULL in that case. This way we don't have
> > two different semantics based on the 'create' value.
> >
>
> Thanks for explaining. I missed the case where create is false and there
> is no heap pool attached, so panthor_vm_get_heap_pool() can return NULL.
>
> 1878 *
> 1879 * Return: A valid pointer on success, an ERR_PTR() otherwise.
> 1880 */
> 1881 struct panthor_heap_pool *panthor_vm_get_heap_pool(struct
> panthor_vm *vm, bool create)
>
> The documentation says it returns ERR_PTR() on failure, so is it worth
> doing something like:
>
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c
> b/drivers/gpu/drm/panthor/panthor_mmu.c
> index fdd35249169f..e1285cdb09ff 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -1893,6 +1893,8 @@ struct panthor_heap_pool
> *panthor_vm_get_heap_pool(struct panthor_vm *vm, bool c
> vm->heaps.pool = panthor_heap_pool_get(pool);
> } else {
> pool = panthor_heap_pool_get(vm->heaps.pool);
> + if (!pool)
> + pool = ERR_PTR(-ENOENT);
> }
> mutex_unlock(&vm->heaps.lock);
>
>
> and change all callers of panthor_vm_get_heap_pool() to only check for
> IS_ERR() ?
Yep, that's what I had in mind.
>
>
> > Oh, and please merge everything into a single patch instead of one patch
> > per call-site.
> >
>
> Sure, I noticed one after the other. I will fix them together in v2.
Great!
Thanks,
Boris
