by Rob Clark

[permalink] [raw]

Subject: Re: [PATCH 6/7] drm/exec: Pass in initial # of objects

On Mon, Oct 30, 2023 at 9:01 AM Christian König
<[email protected]> wrote:
>
> Am 30.10.23 um 14:38 schrieb Rob Clark:
> > On Mon, Oct 30, 2023 at 1:05 AM Christian König
> > <[email protected]> wrote:
> >> Am 27.10.23 um 18:58 schrieb Rob Clark:
> >>> From: Rob Clark <[email protected]>
> >>>
> >>> In cases where the # is known ahead of time, it is silly to do the table
> >>> resize dance.
> >> Ah, yes that was my initial implementation as well, but I ditched that
> >> because nobody actually used it.
> >>
> >> One comment below.
> >>
> >>> Signed-off-by: Rob Clark <[email protected]>
> >>> ---
> >>> drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 2 +-
> >>> drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c | 4 ++--
> >>> drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 4 ++--
> >>> drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c | 4 ++--
> >>> drivers/gpu/drm/drm_exec.c | 15 ++++++++++++---
> >>> drivers/gpu/drm/nouveau/nouveau_exec.c | 2 +-
> >>> drivers/gpu/drm/nouveau/nouveau_uvmm.c | 2 +-
> >>> include/drm/drm_exec.h | 2 +-
> >>> 8 files changed, 22 insertions(+), 13 deletions(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> >>> index efdb1c48f431..d27ca8f61929 100644
> >>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> >>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> >>> @@ -65,7 +65,7 @@ static int amdgpu_cs_parser_init(struct amdgpu_cs_parser *p,
> >>> }
> >>>
> >>> amdgpu_sync_create(&p->sync);
> >>> - drm_exec_init(&p->exec, DRM_EXEC_INTERRUPTIBLE_WAIT);
> >>> + drm_exec_init(&p->exec, DRM_EXEC_INTERRUPTIBLE_WAIT, 0);
> >>> return 0;
> >>> }
> >>>
> >>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c
> >>> index 720011019741..796fa6f1420b 100644
> >>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c
> >>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c
> >>> @@ -70,7 +70,7 @@ int amdgpu_map_static_csa(struct amdgpu_device *adev, struct amdgpu_vm *vm,
> >>> struct drm_exec exec;
> >>> int r;
> >>>
> >>> - drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT);
> >>> + drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT, 0);
> >>> drm_exec_until_all_locked(&exec) {
> >>> r = amdgpu_vm_lock_pd(vm, &exec, 0);
> >>> if (likely(!r))
> >>> @@ -110,7 +110,7 @@ int amdgpu_unmap_static_csa(struct amdgpu_device *adev, struct amdgpu_vm *vm,
> >>> struct drm_exec exec;
> >>> int r;
> >>>
> >>> - drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT);
> >>> + drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT, 0);
> >>> drm_exec_until_all_locked(&exec) {
> >>> r = amdgpu_vm_lock_pd(vm, &exec, 0);
> >>> if (likely(!r))
> >>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> >>> index ca4d2d430e28..16f1715148ad 100644
> >>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> >>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> >>> @@ -203,7 +203,7 @@ static void amdgpu_gem_object_close(struct drm_gem_object *obj,
> >>> struct drm_exec exec;
> >>> long r;
> >>>
> >>> - drm_exec_init(&exec, DRM_EXEC_IGNORE_DUPLICATES);
> >>> + drm_exec_init(&exec, DRM_EXEC_IGNORE_DUPLICATES, 0);
> >>> drm_exec_until_all_locked(&exec) {
> >>> r = drm_exec_prepare_obj(&exec, &bo->tbo.base, 1);
> >>> drm_exec_retry_on_contention(&exec);
> >>> @@ -739,7 +739,7 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
> >>> }
> >>>
> >>> drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT |
> >>> - DRM_EXEC_IGNORE_DUPLICATES);
> >>> + DRM_EXEC_IGNORE_DUPLICATES, 0);
> >>> drm_exec_until_all_locked(&exec) {
> >>> if (gobj) {
> >>> r = drm_exec_lock_obj(&exec, gobj);
> >>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> >>> index b6015157763a..3c351941701e 100644
> >>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> >>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> >>> @@ -1105,7 +1105,7 @@ int amdgpu_mes_ctx_map_meta_data(struct amdgpu_device *adev,
> >>>
> >>> amdgpu_sync_create(&sync);
> >>>
> >>> - drm_exec_init(&exec, 0);
> >>> + drm_exec_init(&exec, 0, 0);
> >>> drm_exec_until_all_locked(&exec) {
> >>> r = drm_exec_lock_obj(&exec,
> >>> &ctx_data->meta_data_obj->tbo.base);
> >>> @@ -1176,7 +1176,7 @@ int amdgpu_mes_ctx_unmap_meta_data(struct amdgpu_device *adev,
> >>> struct drm_exec exec;
> >>> long r;
> >>>
> >>> - drm_exec_init(&exec, 0);
> >>> + drm_exec_init(&exec, 0, 0);
> >>> drm_exec_until_all_locked(&exec) {
> >>> r = drm_exec_lock_obj(&exec,
> >>> &ctx_data->meta_data_obj->tbo.base);
> >>> diff --git a/drivers/gpu/drm/drm_exec.c b/drivers/gpu/drm/drm_exec.c
> >>> index 5d2809de4517..27d11c20d148 100644
> >>> --- a/drivers/gpu/drm/drm_exec.c
> >>> +++ b/drivers/gpu/drm/drm_exec.c
> >>> @@ -69,16 +69,25 @@ static void drm_exec_unlock_all(struct drm_exec *exec)
> >>> * drm_exec_init - initialize a drm_exec object
> >>> * @exec: the drm_exec object to initialize
> >>> * @flags: controls locking behavior, see DRM_EXEC_* defines
> >>> + * @nr: the initial # of objects
> >>> *
> >>> * Initialize the object and make sure that we can track locked objects.
> >>> + *
> >>> + * If nr is non-zero then it is used as the initial objects table size.
> >>> + * In either case, the table will grow (be re-allocated) on demand.
> >>> */
> >>> -void drm_exec_init(struct drm_exec *exec, uint32_t flags)
> >>> +void drm_exec_init(struct drm_exec *exec, uint32_t flags, unsigned nr)
> >>> {
> >>> + size_t sz = PAGE_SIZE;
> >>> +
> >>> + if (nr)
> >>> + sz = (size_t)nr * sizeof(void *);
> >>> +
> >>> exec->flags = flags;
> >>> - exec->objects = kmalloc(PAGE_SIZE, GFP_KERNEL);
> >>> + exec->objects = kmalloc(sz, GFP_KERNEL);
> >> Please use k*v*malloc() here since we can't predict how large that will be.
> > or __GFP_NOWARN? If userspace (or kasan) is cheeky and asks for ~0
> > objects, we should probably just fail?
>
> Oh, good point! If this value is controlled by userspace we must be much
> more careful.
>
> Instead of __GFP_NOWARN or any other workaround we should use
> kvmalloc_array() here.
>
> Maybe turn the code upside down, in other words something like this here:
>
> if (!nr)
> nr = PAGE_SIZE / sizeof(void *);
>
> exec->objects = kvmalloc_array(nr, sizeof(void *), GFP_KERNEL);
> exec->max_objects = exec->objects ? nr : 0;

oh, good point

BR,
-R

>
> Regards,
> Christian.
>
> >
> > BR,
> > -R
> >
> >> With that fixed the patch is Reviewed-by: Christian König
> >> <[email protected]>.
> >>
> >> Regards,
> >> Christian.
> >>
> >>> /* If allocation here fails, just delay that till the first use */
> >>> - exec->max_objects = exec->objects ? PAGE_SIZE / sizeof(void *) : 0;
> >>> + exec->max_objects = exec->objects ? sz / sizeof(void *) : 0;
> >>> exec->num_objects = 0;
> >>> exec->contended = DRM_EXEC_DUMMY;
> >>> exec->prelocked = NULL;
> >>> diff --git a/drivers/gpu/drm/nouveau/nouveau_exec.c b/drivers/gpu/drm/nouveau/nouveau_exec.c
> >>> index 19024ce21fbb..f5930cc0b3fb 100644
> >>> --- a/drivers/gpu/drm/nouveau/nouveau_exec.c
> >>> +++ b/drivers/gpu/drm/nouveau/nouveau_exec.c
> >>> @@ -103,7 +103,7 @@ nouveau_exec_job_submit(struct nouveau_job *job)
> >>>
> >>> nouveau_uvmm_lock(uvmm);
> >>> drm_exec_init(exec, DRM_EXEC_INTERRUPTIBLE_WAIT |
> >>> - DRM_EXEC_IGNORE_DUPLICATES);
> >>> + DRM_EXEC_IGNORE_DUPLICATES, 0);
> >>> drm_exec_until_all_locked(exec) {
> >>> struct drm_gpuva *va;
> >>>
> >>> diff --git a/drivers/gpu/drm/nouveau/nouveau_uvmm.c b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> >>> index aae780e4a4aa..3a9331a1c830 100644
> >>> --- a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> >>> +++ b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> >>> @@ -1288,7 +1288,7 @@ nouveau_uvmm_bind_job_submit(struct nouveau_job *job)
> >>> }
> >>>
> >>> drm_exec_init(exec, DRM_EXEC_INTERRUPTIBLE_WAIT |
> >>> - DRM_EXEC_IGNORE_DUPLICATES);
> >>> + DRM_EXEC_IGNORE_DUPLICATES, 0);
> >>> drm_exec_until_all_locked(exec) {
> >>> list_for_each_op(op, &bind_job->ops) {
> >>> struct drm_gpuva_op *va_op;
> >>> diff --git a/include/drm/drm_exec.h b/include/drm/drm_exec.h
> >>> index b5bf0b6da791..f1a66c048721 100644
> >>> --- a/include/drm/drm_exec.h
> >>> +++ b/include/drm/drm_exec.h
> >>> @@ -135,7 +135,7 @@ static inline bool drm_exec_is_contended(struct drm_exec *exec)
> >>> return !!exec->contended;
> >>> }
> >>>
> >>> -void drm_exec_init(struct drm_exec *exec, uint32_t flags);
> >>> +void drm_exec_init(struct drm_exec *exec, uint32_t flags, unsigned nr);
> >>> void drm_exec_fini(struct drm_exec *exec);
> >>> bool drm_exec_cleanup(struct drm_exec *exec);
> >>> int drm_exec_lock_obj(struct drm_exec *exec, struct drm_gem_object *obj);
>