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 <[email protected]>
---
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
--
2.39.3
On Tue, 2 Apr 2024 07:14:11 -0700
Harshit Mogalapalli <[email protected]> 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
^ pool
> 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")
I would explain that the code was correct, but the documentation didn't
match the function behavior, otherwise it feels a bit weird to have a
Fixes tag here.
> Signed-off-by: Harshit Mogalapalli <[email protected]>
> ---
> 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
On Tue, Apr 02, 2024 at 04:38:38PM +0200, Boris Brezillon wrote:
> On Tue, 2 Apr 2024 07:14:11 -0700
> Harshit Mogalapalli <[email protected]> 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
>
> ^ pool
>
> > 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")
>
> I would explain that the code was correct, but the documentation didn't
> match the function behavior, otherwise it feels a bit weird to have a
> Fixes tag here.
The code wasn't correct, it returned a mix of error pointers and NULL.
So it needs a Fixes tag.
regards,
dan carpenter
On Tue, 2 Apr 2024 17:44:18 +0300
Dan Carpenter <[email protected]> wrote:
> On Tue, Apr 02, 2024 at 04:38:38PM +0200, Boris Brezillon wrote:
> > On Tue, 2 Apr 2024 07:14:11 -0700
> > Harshit Mogalapalli <[email protected]> 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
> >
> > ^ pool
> >
> > > 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")
> >
> > I would explain that the code was correct, but the documentation didn't
> > match the function behavior, otherwise it feels a bit weird to have a
> > Fixes tag here.
>
> The code wasn't correct, it returned a mix of error pointers and NULL.
AFAICT, this is allowed, otherwise why would we have IS_ERR_OR_NULL().
The fact smatch can't see through panthor_vm_get_heap_pool() and detect
that the return value is different for create=false/true doesn't mean
the code was wrong. I'm certainly not saying this is a good thing to
have a function that encodes the error case with two different kind of
return value, but I wouldn't qualify it as a bug either. What's
incorrect though, is the fact the documentation doesn't match the code.
> So it needs a Fixes tag.
I didn't say we should drop the Fixes tag, but the bug being fixed here
is a mismatch between the doc and the implementation, the code itself
was correct, and the behavior is actually unchanged with this patch
applied, it's just done in a less confusing way.
Regards,
Boris
On Tue, Apr 02, 2024 at 05:19:25PM +0200, Boris Brezillon wrote:
> On Tue, 2 Apr 2024 17:44:18 +0300
> Dan Carpenter <[email protected]> wrote:
>
> > On Tue, Apr 02, 2024 at 04:38:38PM +0200, Boris Brezillon wrote:
> > > On Tue, 2 Apr 2024 07:14:11 -0700
> > > Harshit Mogalapalli <[email protected]> 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
> > >
> > > ^ pool
> > >
> > > > 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")
> > >
> > > I would explain that the code was correct, but the documentation didn't
> > > match the function behavior, otherwise it feels a bit weird to have a
> > > Fixes tag here.
> >
> > The code wasn't correct, it returned a mix of error pointers and NULL.
>
> AFAICT, this is allowed, otherwise why would we have IS_ERR_OR_NULL().
Yep. I have written a blog about this:
https://staticthinking.wordpress.com/2022/08/01/mixing-error-pointers-and-null/
> The fact smatch can't see through panthor_vm_get_heap_pool() and detect
> that the return value is different for create=false/true doesn't mean
> the code was wrong. I'm certainly not saying this is a good thing to
> have a function that encodes the error case with two different kind of
> return value, but I wouldn't qualify it as a bug either. What's
> incorrect though, is the fact the documentation doesn't match the code.
>
> > So it needs a Fixes tag.
>
> I didn't say we should drop the Fixes tag, but the bug being fixed here
> is a mismatch between the doc and the implementation, the code itself
> was correct, and the behavior is actually unchanged with this patch
> applied, it's just done in a less confusing way.
Oh. Sorry, I haven't been following this thread closely and I misread
the code as well. You're right that the code works. In this case, I
would say actually that it does not need a Fixes tag because it's not
a bug. It's just a cleanup.
Sorry for the noise.
regards,
dan carpenter
On Tue, 2 Apr 2024 07:14:11 -0700
Harshit Mogalapalli <[email protected]> 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 <[email protected]>
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
Hi Boris,
On 03/04/24 12:47, Boris Brezillon wrote:
> On Tue, 2 Apr 2024 07:14:11 -0700
> Harshit Mogalapalli <[email protected]> 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 <[email protected]>
>
> 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 a lot for making the change!
Regards,
Harshit
> 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
>