On Wed, 29 May 2019 at 11:18, Boris Brezillon
<boris.brezillon@xxxxxxxxxxxxx> wrote:
>
> mmu_ops->unmap() will fail when called on a BO that has not been
> previously mapped, and the error path in panfrost_ioctl_create_bo()
> can call drm_gem_object_put_unlocked() (which in turn calls
> panfrost_mmu_unmap()) on a BO that has not been mapped yet.
>
> Keep track of the mapped/unmapped state to avoid such issues.
>
> Fixes: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/panfrost/panfrost_gem.h | 1 +
> drivers/gpu/drm/panfrost/panfrost_mmu.c | 8 ++++++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h
> index 045000eb5fcf..6dbcaba020fc 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
> @@ -11,6 +11,7 @@ struct panfrost_gem_object {
> struct drm_gem_shmem_object base;
>
> struct drm_mm_node node;
> + bool is_mapped;
> };
>
> static inline
> diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> index 762b1bd2a8c2..fb556aa89203 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> @@ -156,6 +156,9 @@ int panfrost_mmu_map(struct panfrost_gem_object *bo)
> struct sg_table *sgt;
> int ret;
>
> + if (bo->is_mapped)
> + return 0;
In what circumstances we want to silently go on? I would expect that
for this function to be called when the BO has been mapped already
would mean that we have a bug in the kernel, so why not a WARN?
> +
> sgt = drm_gem_shmem_get_pages_sgt(obj);
> if (WARN_ON(IS_ERR(sgt)))
> return PTR_ERR(sgt);
> @@ -189,6 +192,7 @@ int panfrost_mmu_map(struct panfrost_gem_object *bo)
>
> pm_runtime_mark_last_busy(pfdev->dev);
> pm_runtime_put_autosuspend(pfdev->dev);
> + bo->is_mapped = true;
>
> return 0;
> }
> @@ -203,6 +207,9 @@ void panfrost_mmu_unmap(struct panfrost_gem_object *bo)
> size_t unmapped_len = 0;
> int ret;
>
> + if (!bo->is_mapped)
> + return;
Similarly, I think that what we should do is not to call
panfrost_mmu_unmap when a BO is freed if we know it isn't mapped. And
probably add a WARN here if it still gets called when the BO isn't
mapped.
> +
> dev_dbg(pfdev->dev, "unmap: iova=%llx, len=%zx", iova, len);
>
> ret = pm_runtime_get_sync(pfdev->dev);
> @@ -230,6 +237,7 @@ void panfrost_mmu_unmap(struct panfrost_gem_object *bo)
>
> pm_runtime_mark_last_busy(pfdev->dev);
> pm_runtime_put_autosuspend(pfdev->dev);
> + bo->is_mapped = false;
> }
>
> static void mmu_tlb_inv_context_s1(void *cookie)
> --
> 2.20.1
>
Thanks for taking care of this!
Tomeu
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