drm/etnaviv: convert user fence tracking to XArray

This simplifies the driver code a bit, as XArray already provides
internal locking. IDRs are implemented using XArrays anyways, so
this drops one level of unneeded abstraction.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>

Author: lynxeye-dev

drivers/gpu/drm/etnaviv/etnaviv_drv.h

@@ -12,6 +12,7 @@
 #include <linux/sizes.h>
 #include <linux/time64.h>
 #include <linux/types.h>
+#include <linux/xarray.h>
 
 #include <drm/drm_drv.h>
 #include <drm/drm_gem.h>

drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c

@@ -393,10 +393,11 @@ static void submit_cleanup(struct kref *kref)
 	wake_up_all(&submit->gpu->fence_event);
 
 	if (submit->out_fence) {
-		/* first remove from IDR, so fence can not be found anymore */
-		mutex_lock(&submit->gpu->idr_lock);
-		idr_remove(&submit->gpu->fence_idr, submit->out_fence_id);
-		mutex_unlock(&submit->gpu->idr_lock);
+		/*
+		 * Remove from user fence array before dropping the reference,
+		 * so fence can not be found in lookup anymore.
+		 */
+		xa_erase(&submit->gpu->user_fences, submit->out_fence_id);
 		dma_fence_put(submit->out_fence);
 	}
 

drivers/gpu/drm/etnaviv/etnaviv_gpu.c

@@ -1244,7 +1244,7 @@ int etnaviv_gpu_wait_fence_interruptible(struct etnaviv_gpu *gpu,
 	 * pretends we didn't find a fence in that case.
 	 */
 	rcu_read_lock();
-	fence = idr_find(&gpu->fence_idr, id);
+	fence = xa_load(&gpu->user_fences, id);
 	if (fence)
 		fence = dma_fence_get_rcu(fence);
 	rcu_read_unlock();
@@ -1744,7 +1744,7 @@ static int etnaviv_gpu_bind(struct device *dev, struct device *master,
 
 	gpu->drm = drm;
 	gpu->fence_context = dma_fence_context_alloc(1);
-	idr_init(&gpu->fence_idr);
+	xa_init_flags(&gpu->user_fences, XA_FLAGS_ALLOC);
 	spin_lock_init(&gpu->fence_spinlock);
 
 	INIT_WORK(&gpu->sync_point_work, sync_point_worker);
@@ -1798,7 +1798,7 @@ static void etnaviv_gpu_unbind(struct device *dev, struct device *master,
 	}
 
 	gpu->drm = NULL;
-	idr_destroy(&gpu->fence_idr);
+	xa_destroy(&gpu->user_fences);
 
 	if (IS_ENABLED(CONFIG_DRM_ETNAVIV_THERMAL))
 		thermal_cooling_device_unregister(gpu->cooling);
@@ -1831,7 +1831,6 @@ static int etnaviv_gpu_platform_probe(struct platform_device *pdev)
 	gpu->dev = &pdev->dev;
 	mutex_init(&gpu->lock);
 	mutex_init(&gpu->sched_lock);
-	mutex_init(&gpu->idr_lock);
 
 	/* Map registers: */
 	gpu->mmio = devm_platform_ioremap_resource(pdev, 0);

drivers/gpu/drm/etnaviv/etnaviv_gpu.h

@@ -121,8 +121,8 @@ struct etnaviv_gpu {
 	u32 idle_mask;
 
 	/* Fencing support */
-	struct mutex idr_lock;
-	struct idr fence_idr;
+	struct xarray user_fences;
+	u32 next_user_fence;
 	u32 next_fence;
 	u32 completed_fence;
 	wait_queue_head_t fence_event;

drivers/gpu/drm/etnaviv/etnaviv_sched.c

@@ -98,7 +98,7 @@ static const struct drm_sched_backend_ops etnaviv_sched_ops = {
 int etnaviv_sched_push_job(struct etnaviv_gem_submit *submit)
 {
 	struct etnaviv_gpu *gpu = submit->gpu;
-	int ret = 0;
+	int ret;
 
 	/*
 	 * Hold the sched lock across the whole operation to avoid jobs being
@@ -110,14 +110,11 @@ int etnaviv_sched_push_job(struct etnaviv_gem_submit *submit)
 	drm_sched_job_arm(&submit->sched_job);
 
 	submit->out_fence = dma_fence_get(&submit->sched_job.s_fence->finished);
-	mutex_lock(&gpu->idr_lock);
-	submit->out_fence_id = idr_alloc_cyclic(&gpu->fence_idr,
-						submit->out_fence, 0,
-						INT_MAX, GFP_KERNEL);
-	mutex_unlock(&gpu->idr_lock);
-	if (submit->out_fence_id < 0) {
+	ret = xa_alloc_cyclic(&gpu->user_fences, &submit->out_fence_id,
+			      submit->out_fence, xa_limit_32b,
+			      &gpu->next_user_fence, GFP_KERNEL);
+	if (ret < 0) {
 		drm_sched_job_cleanup(&submit->sched_job);
-		ret = -ENOMEM;
 		goto out_unlock;
 	}