On Tue, 2 Apr 2024 07:14:11 -0700
Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx> wrote:
> Currently panthor_vm_get_heap_pool() returns both ERR_PTR() and
> NULL(when create is false and if there is no poool attached to the
> VM)
> - Change the function to return error pointers, when pool is
> NULL return -ENOENT
> - Also handle the callers to check for IS_ERR() on failure.
>
> Fixes: 4bdca1150792 ("drm/panthor: Add the driver frontend block")
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx>
Queued to drm-misc-next with the following commit message:
"
drm/panthor: Don't return NULL from panthor_vm_get_heap_pool()
The kernel doc says this function returns either a valid pointer
or an ERR_PTR(), but in practice this function can return NULL if
create=false. Fix the function to match the doc (return
ERR_PTR(-ENOENT) instead of NULL) and adjust all call-sites
accordingly.
"
Thanks,
Boris
> ---
> This is spotted by smatch and the patch is only compile tested
>
> v1->v2: Fix the function panthor_vm_get_heap_pool() to only return error
> pointers and handle the caller sites [Suggested by Boris Brezillon]
> - Also merge these IS_ERR() vs NULL bugs into same patch
>
> v2->v3: pull out error checking for devm_drm_dev_alloc() failure.
> ---
> drivers/gpu/drm/panthor/panthor_drv.c | 4 ++--
> drivers/gpu/drm/panthor/panthor_mmu.c | 2 ++
> drivers/gpu/drm/panthor/panthor_sched.c | 2 +-
> 3 files changed, 5 insertions(+), 3 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);
> goto out_put_vm;
> }
>
> 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);
>
> diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
> index 5f7803b6fc48..617df2b980d0 100644
> --- a/drivers/gpu/drm/panthor/panthor_sched.c
> +++ b/drivers/gpu/drm/panthor/panthor_sched.c
> @@ -1343,7 +1343,7 @@ static int group_process_tiler_oom(struct panthor_group *group, u32 cs_id)
> if (unlikely(csg_id < 0))
> return 0;
>
> - if (!heaps || frag_end > vt_end || vt_end >= vt_start) {
> + if (IS_ERR(heaps) || frag_end > vt_end || vt_end >= vt_start) {
> ret = -EINVAL;
> } else {
> /* We do the allocation without holding the scheduler lock to avoid
