From: Melissa Wen Date: Tue, 16 Sep 2025 17:18:28 +0000 (-0300) Subject: drm/v3d: create a dedicated lock for dma fence X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=adefb2ccea1e96b452cbbc39150bc0ccf1688b99;p=users%2Fhch%2Fmisc.git drm/v3d: create a dedicated lock for dma fence Don't mix dma fence lock with the active_job lock. Use fence_lock to protect the dma fence used by drm scheduler when signalling a job completion and queue_lock to protect concurrent access to active bin job in OOM and stats collection for a given file priv. The issue was uncovered when PREEMPT_RT on with a system freeze when opening multiple Chromium tabs on Raspberry Pi 5. Link: https://github.com/raspberrypi/linux/issues/7035 Fixes: fa6a20c87470 ("drm/v3d: Address race-condition between per-fd GPU stats and fd release") Signed-off-by: Melissa Wen Acked-by: Iago Toral Quiroga Reviewed-by: Maíra Canal Signed-off-by: Melissa Wen Link: https://lore.kernel.org/r/20250916172022.2779837-1-mwen@igalia.com --- diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h index 0317f3d7452a..1884686985b8 100644 --- a/drivers/gpu/drm/v3d/v3d_drv.h +++ b/drivers/gpu/drm/v3d/v3d_drv.h @@ -62,6 +62,8 @@ struct v3d_queue_state { /* Currently active job for this queue */ struct v3d_job *active_job; spinlock_t queue_lock; + /* Protect dma fence for signalling job completion */ + spinlock_t fence_lock; }; /* Performance monitor object. The perform lifetime is controlled by userspace diff --git a/drivers/gpu/drm/v3d/v3d_fence.c b/drivers/gpu/drm/v3d/v3d_fence.c index 8f8471adae34..c82500a1df73 100644 --- a/drivers/gpu/drm/v3d/v3d_fence.c +++ b/drivers/gpu/drm/v3d/v3d_fence.c @@ -15,7 +15,7 @@ struct dma_fence *v3d_fence_create(struct v3d_dev *v3d, enum v3d_queue q) fence->dev = &v3d->drm; fence->queue = q; fence->seqno = ++queue->emit_seqno; - dma_fence_init(&fence->base, &v3d_fence_ops, &queue->queue_lock, + dma_fence_init(&fence->base, &v3d_fence_ops, &queue->fence_lock, queue->fence_context, fence->seqno); return &fence->base; diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c index c77d90aa9b82..bb110d35f749 100644 --- a/drivers/gpu/drm/v3d/v3d_gem.c +++ b/drivers/gpu/drm/v3d/v3d_gem.c @@ -273,6 +273,7 @@ v3d_gem_init(struct drm_device *dev) seqcount_init(&queue->stats.lock); spin_lock_init(&queue->queue_lock); + spin_lock_init(&queue->fence_lock); } spin_lock_init(&v3d->mm_lock);