[PATCH v3 2/3] drm/etnaviv: allocate unique ID per drm_file

[Lucas Stach <l.stach@pengutronix.de>]

Allows to easily track if several fd are pointing to the same
execution context due to being dup'ed.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
---
v3: use xarray to track the active contexts to avoid issues
    on rollover
---
 drivers/gpu/drm/etnaviv/etnaviv_drv.c | 11 +++++++++++
 drivers/gpu/drm/etnaviv/etnaviv_drv.h |  4 ++++
 2 files changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
index 1d2b4fb4bcf8..31a7f59ccb49 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
@@ -56,6 +56,11 @@ static int etnaviv_open(struct drm_device *dev, struct drm_file *file)
 	if (!ctx)
 		return -ENOMEM;
 
+	ret = xa_alloc_cyclic(&priv->active_contexts, &ctx->id, ctx,
+			      xa_limit_32b, &priv->next_context_id, GFP_KERNEL);
+	if (ret < 0)
+		goto out_free;
+
 	ctx->mmu = etnaviv_iommu_context_init(priv->mmu_global,
 					      priv->cmdbuf_suballoc);
 	if (!ctx->mmu) {
@@ -99,6 +104,8 @@ static void etnaviv_postclose(struct drm_device *dev, struct drm_file *file)
 
 	etnaviv_iommu_context_put(ctx->mmu);
 
+	xa_erase(&priv->active_contexts, ctx->id);
+
 	kfree(ctx);
 }
 
@@ -514,6 +521,8 @@ static int etnaviv_bind(struct device *dev)
 
 	dma_set_max_seg_size(dev, SZ_2G);
 
+	xa_init_flags(&priv->active_contexts, XA_FLAGS_ALLOC);
+
 	mutex_init(&priv->gem_lock);
 	INIT_LIST_HEAD(&priv->gem_list);
 	priv->num_gpus = 0;
@@ -563,6 +572,8 @@ static void etnaviv_unbind(struct device *dev)
 
 	etnaviv_cmdbuf_suballoc_destroy(priv->cmdbuf_suballoc);
 
+	xa_destroy(&priv->active_contexts);
+
 	drm->dev_private = NULL;
 	kfree(priv);
 
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.h b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
index 0b311af04f1d..b3eb1662e90c 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_drv.h
+++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
@@ -29,6 +29,7 @@ struct etnaviv_iommu_global;
 #define ETNAVIV_SOFTPIN_START_ADDRESS	SZ_4M /* must be >= SUBALLOC_SIZE */
 
 struct etnaviv_file_private {
+	int id;
 	struct etnaviv_iommu_context	*mmu;
 	struct drm_sched_entity		sched_entity[ETNA_MAX_PIPES];
 };
@@ -41,6 +42,9 @@ struct etnaviv_drm_private {
 	struct etnaviv_cmdbuf_suballoc *cmdbuf_suballoc;
 	struct etnaviv_iommu_global *mmu_global;
 
+	struct xarray active_contexts;
+	u32 next_context_id;
+
 	/* list of GEM objects: */
 	struct mutex gem_lock;
 	struct list_head gem_list;
-- 
2.39.1