On Thu, 2 May 2024 16:52:24 +0100
Steven Price <steven.price@xxxxxxx> wrote:
> On 02/05/2024 16:40, Boris Brezillon wrote:
> > The heap ID is used to index the heap context pool, and allocating
> > in the [1:MAX_HEAPS_PER_POOL] leads to an off-by-one. This was
> > originally to avoid returning a zero heap handle, but given the handle
> > is formed with (vm_id << 16) | heap_id, with vm_id > 0, we already can't
> > end up with a valid heap handle that's zero.
> >
> > v3:
> > - Allocate in the [0:MAX_HEAPS_PER_POOL-1] range
> >
> > v2:
> > - New patch
> >
> > Fixes: 9cca48fa4f89 ("drm/panthor: Add the heap logical block")
> > Reported-by: Eric Smith <eric.smith@xxxxxxxxxxxxx>
> > Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> > Tested-by: Eric Smith <eric.smith@xxxxxxxxxxxxx>
>
> Don't we also need to change the xa_init_flags() in
> panthor_heap_pool_create()?
Uh, we should, indeed.
>
> Steve
>
> > ---
> > drivers/gpu/drm/panthor/panthor_heap.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/panthor/panthor_heap.c b/drivers/gpu/drm/panthor/panthor_heap.c
> > index 683bb94761bc..252332f5390f 100644
> > --- a/drivers/gpu/drm/panthor/panthor_heap.c
> > +++ b/drivers/gpu/drm/panthor/panthor_heap.c
> > @@ -323,7 +323,8 @@ int panthor_heap_create(struct panthor_heap_pool *pool,
> > if (!pool->vm) {
> > ret = -EINVAL;
> > } else {
> > - ret = xa_alloc(&pool->xa, &id, heap, XA_LIMIT(1, MAX_HEAPS_PER_POOL), GFP_KERNEL);
> > + ret = xa_alloc(&pool->xa, &id, heap,
> > + XA_LIMIT(0, MAX_HEAPS_PER_POOL - 1), GFP_KERNEL);
> > if (!ret) {
> > void *gpu_ctx = panthor_get_heap_ctx(pool, id);
> >
>
