Re: [PATCH drm-misc-next] drm/nouveau: fence: fix undefined fence state after emit
From: Dave Airlie
Date: Tue Aug 29 2023 - 18:48:24 EST
On Wed, 30 Aug 2023 at 08:38, Danilo Krummrich <dakr@xxxxxxxxxx> wrote:
>
> nouveau_fence_emit() can fail before and after initializing the
> dma-fence and hence before and after initializing the dma-fence' kref.
>
> In order to avoid nouveau_fence_emit() potentially failing before
> dma-fence initialization pass the channel to nouveau_fence_new() already
> and perform the required check before even allocating the fence.
>
> While at it, restore the original behavior of nouveau_fence_new() and
> add nouveau_fence_create() for separate (pre-)allocation instead. Always
> splitting up allocation end emit wasn't a good idea in the first place.
> Hence, limit it to the places where we actually need to pre-allocate.
>
> Fixes: 7f2a0b50b2b2 ("drm/nouveau: fence: separate fence alloc and emit")
> Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
nice find,
Reviewed-by: Dave Airlie <airlied@xxxxxxxxxx>
> ---
> drivers/gpu/drm/nouveau/dispnv04/crtc.c | 9 +------
> drivers/gpu/drm/nouveau/nouveau_bo.c | 8 +------
> drivers/gpu/drm/nouveau/nouveau_chan.c | 6 ++---
> drivers/gpu/drm/nouveau/nouveau_dmem.c | 9 +++----
> drivers/gpu/drm/nouveau/nouveau_exec.c | 11 ++++++---
> drivers/gpu/drm/nouveau/nouveau_fence.c | 32 ++++++++++++++++++++-----
> drivers/gpu/drm/nouveau/nouveau_fence.h | 5 ++--
> drivers/gpu/drm/nouveau/nouveau_gem.c | 5 +---
> 8 files changed, 45 insertions(+), 40 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/dispnv04/crtc.c b/drivers/gpu/drm/nouveau/dispnv04/crtc.c
> index a34924523133..a34917b048f9 100644
> --- a/drivers/gpu/drm/nouveau/dispnv04/crtc.c
> +++ b/drivers/gpu/drm/nouveau/dispnv04/crtc.c
> @@ -1122,18 +1122,11 @@ nv04_page_flip_emit(struct nouveau_channel *chan,
> PUSH_NVSQ(push, NV_SW, NV_SW_PAGE_FLIP, 0x00000000);
> PUSH_KICK(push);
>
> - ret = nouveau_fence_new(pfence);
> + ret = nouveau_fence_new(pfence, chan);
> if (ret)
> goto fail;
>
> - ret = nouveau_fence_emit(*pfence, chan);
> - if (ret)
> - goto fail_fence_unref;
> -
> return 0;
> -
> -fail_fence_unref:
> - nouveau_fence_unref(pfence);
> fail:
> spin_lock_irqsave(&dev->event_lock, flags);
> list_del(&s->head);
> diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
> index 64f50adb2856..56427b6a00a4 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_bo.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
> @@ -875,16 +875,10 @@ nouveau_bo_move_m2mf(struct ttm_buffer_object *bo, int evict,
> if (ret)
> goto out_unlock;
>
> - ret = nouveau_fence_new(&fence);
> + ret = nouveau_fence_new(&fence, chan);
> if (ret)
> goto out_unlock;
>
> - ret = nouveau_fence_emit(fence, chan);
> - if (ret) {
> - nouveau_fence_unref(&fence);
> - goto out_unlock;
> - }
> -
> /* TODO: figure out a better solution here
> *
> * wait on the fence here explicitly as going through
> diff --git a/drivers/gpu/drm/nouveau/nouveau_chan.c b/drivers/gpu/drm/nouveau/nouveau_chan.c
> index 1fd5ccf41128..bb3d6e5c122f 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_chan.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_chan.c
> @@ -70,11 +70,9 @@ nouveau_channel_idle(struct nouveau_channel *chan)
> struct nouveau_fence *fence = NULL;
> int ret;
>
> - ret = nouveau_fence_new(&fence);
> + ret = nouveau_fence_new(&fence, chan);
> if (!ret) {
> - ret = nouveau_fence_emit(fence, chan);
> - if (!ret)
> - ret = nouveau_fence_wait(fence, false, false);
> + ret = nouveau_fence_wait(fence, false, false);
> nouveau_fence_unref(&fence);
> }
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
> index 61e84562094a..12feecf71e75 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
> @@ -209,8 +209,7 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf)
> goto done;
> }
>
> - if (!nouveau_fence_new(&fence))
> - nouveau_fence_emit(fence, dmem->migrate.chan);
> + nouveau_fence_new(&fence, dmem->migrate.chan);
> migrate_vma_pages(&args);
> nouveau_dmem_fence_done(&fence);
> dma_unmap_page(drm->dev->dev, dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
> @@ -403,8 +402,7 @@ nouveau_dmem_evict_chunk(struct nouveau_dmem_chunk *chunk)
> }
> }
>
> - if (!nouveau_fence_new(&fence))
> - nouveau_fence_emit(fence, chunk->drm->dmem->migrate.chan);
> + nouveau_fence_new(&fence, chunk->drm->dmem->migrate.chan);
> migrate_device_pages(src_pfns, dst_pfns, npages);
> nouveau_dmem_fence_done(&fence);
> migrate_device_finalize(src_pfns, dst_pfns, npages);
> @@ -677,8 +675,7 @@ static void nouveau_dmem_migrate_chunk(struct nouveau_drm *drm,
> addr += PAGE_SIZE;
> }
>
> - if (!nouveau_fence_new(&fence))
> - nouveau_fence_emit(fence, drm->dmem->migrate.chan);
> + nouveau_fence_new(&fence, drm->dmem->migrate.chan);
> migrate_vma_pages(args);
> nouveau_dmem_fence_done(&fence);
> nouveau_pfns_map(svmm, args->vma->vm_mm, args->start, pfns, i);
> diff --git a/drivers/gpu/drm/nouveau/nouveau_exec.c b/drivers/gpu/drm/nouveau/nouveau_exec.c
> index 98a7a94cec5a..72f6543a0790 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_exec.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_exec.c
> @@ -91,7 +91,8 @@ nouveau_exec_job_submit(struct nouveau_job *job)
> struct nouveau_uvmm *uvmm = nouveau_cli_uvmm(cli);
> int ret;
>
> - ret = nouveau_fence_new(&exec_job->fence);
> + /* Create a new fence, but do not emit yet. */
> + ret = nouveau_fence_create(&exec_job->fence, exec_job->chan);
> if (ret)
> return ret;
>
> @@ -143,13 +144,17 @@ nouveau_exec_job_run(struct nouveau_job *job)
> nv50_dma_push(chan, p->va, p->va_len, no_prefetch);
> }
>
> - ret = nouveau_fence_emit(fence, chan);
> + ret = nouveau_fence_emit(fence);
> if (ret) {
> + nouveau_fence_unref(&exec_job->fence);
> NV_PRINTK(err, job->cli, "error fencing pushbuf: %d\n", ret);
> WIND_RING(chan);
> return ERR_PTR(ret);
> }
>
> + /* The fence was emitted successfully, set the job's fence pointer to
> + * NULL in order to avoid freeing it up when the job is cleaned up.
> + */
> exec_job->fence = NULL;
>
> return &fence->base;
> @@ -162,7 +167,7 @@ nouveau_exec_job_free(struct nouveau_job *job)
>
> nouveau_job_free(job);
>
> - nouveau_fence_unref(&exec_job->fence);
> + kfree(exec_job->fence);
> kfree(exec_job->push.s);
> kfree(exec_job);
> }
> diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
> index 77c739a55b19..61d9e70da9fd 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_fence.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
> @@ -205,16 +205,13 @@ nouveau_fence_context_new(struct nouveau_channel *chan, struct nouveau_fence_cha
> }
>
> int
> -nouveau_fence_emit(struct nouveau_fence *fence, struct nouveau_channel *chan)
> +nouveau_fence_emit(struct nouveau_fence *fence)
> {
> + struct nouveau_channel *chan = fence->channel;
> struct nouveau_fence_chan *fctx = chan->fence;
> struct nouveau_fence_priv *priv = (void*)chan->drm->fence;
> int ret;
>
> - if (unlikely(!chan->fence))
> - return -ENODEV;
> -
> - fence->channel = chan;
> fence->timeout = jiffies + (15 * HZ);
>
> if (priv->uevent)
> @@ -406,18 +403,41 @@ nouveau_fence_unref(struct nouveau_fence **pfence)
> }
>
> int
> -nouveau_fence_new(struct nouveau_fence **pfence)
> +nouveau_fence_create(struct nouveau_fence **pfence,
> + struct nouveau_channel *chan)
> {
> struct nouveau_fence *fence;
>
> + if (unlikely(!chan->fence))
> + return -ENODEV;
> +
> fence = kzalloc(sizeof(*fence), GFP_KERNEL);
> if (!fence)
> return -ENOMEM;
>
> + fence->channel = chan;
> +
> *pfence = fence;
> return 0;
> }
>
> +int
> +nouveau_fence_new(struct nouveau_fence **pfence,
> + struct nouveau_channel *chan)
> +{
> + int ret = 0;
> +
> + ret = nouveau_fence_create(pfence, chan);
> + if (ret)
> + return ret;
> +
> + ret = nouveau_fence_emit(*pfence);
> + if (ret)
> + nouveau_fence_unref(pfence);
> +
> + return ret;
> +}
> +
> static const char *nouveau_fence_get_get_driver_name(struct dma_fence *fence)
> {
> return "nouveau";
> diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.h b/drivers/gpu/drm/nouveau/nouveau_fence.h
> index 2c72d96ef17d..64d33ae7f356 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_fence.h
> +++ b/drivers/gpu/drm/nouveau/nouveau_fence.h
> @@ -17,10 +17,11 @@ struct nouveau_fence {
> unsigned long timeout;
> };
>
> -int nouveau_fence_new(struct nouveau_fence **);
> +int nouveau_fence_create(struct nouveau_fence **, struct nouveau_channel *);
> +int nouveau_fence_new(struct nouveau_fence **, struct nouveau_channel *);
> void nouveau_fence_unref(struct nouveau_fence **);
>
> -int nouveau_fence_emit(struct nouveau_fence *, struct nouveau_channel *);
> +int nouveau_fence_emit(struct nouveau_fence *);
> bool nouveau_fence_done(struct nouveau_fence *);
> int nouveau_fence_wait(struct nouveau_fence *, bool lazy, bool intr);
> int nouveau_fence_sync(struct nouveau_bo *, struct nouveau_channel *, bool exclusive, bool intr);
> diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
> index a03fe3e92059..254524fee4fb 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_gem.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
> @@ -914,11 +914,8 @@ nouveau_gem_ioctl_pushbuf(struct drm_device *dev, void *data,
> }
> }
>
> - ret = nouveau_fence_new(&fence);
> - if (!ret)
> - ret = nouveau_fence_emit(fence, chan);
> + ret = nouveau_fence_new(&fence, chan);
> if (ret) {
> - nouveau_fence_unref(&fence);
> NV_PRINTK(err, cli, "error fencing pushbuf: %d\n", ret);
> WIND_RING(chan);
> goto out;
> --
> 2.41.0
>