linux-kernel - [PATCH 1/1] drm/lima: implement the file flush callback

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Message-ID: <20250408154637.1637082-2-nunes.erico@gmail.com>
Date: Tue,  8 Apr 2025 17:46:37 +0200
From: Erico Nunes <nunes.erico@...il.com>
To: Qiang Yu <yuq825@...il.com>
Cc: christian.koenig@....com,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	dri-devel@...ts.freedesktop.org,
	lima@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Erico Nunes <nunes.erico@...il.com>
Subject: [PATCH 1/1] drm/lima: implement the file flush callback

With this callback implemented, a terminating application will wait for
the sched entity to be flushed out to the hardware and cancel all other
pending jobs before destroying its context.
This prevents applications with multiple contexts from running into a
race condition between running tasks and context destroy when
terminating.

Signed-off-by: Erico Nunes <nunes.erico@...il.com>
---
 drivers/gpu/drm/lima/lima_ctx.c | 18 ++++++++++++++++++
 drivers/gpu/drm/lima/lima_ctx.h |  1 +
 drivers/gpu/drm/lima/lima_drv.c | 17 ++++++++++++++++-
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/lima/lima_ctx.c b/drivers/gpu/drm/lima/lima_ctx.c
index 0e668fc1e0f9..e8fb5788ca69 100644
--- a/drivers/gpu/drm/lima/lima_ctx.c
+++ b/drivers/gpu/drm/lima/lima_ctx.c
@@ -100,3 +100,21 @@ void lima_ctx_mgr_fini(struct lima_ctx_mgr *mgr)
 	xa_destroy(&mgr->handles);
 	mutex_destroy(&mgr->lock);
 }
+
+long lima_ctx_mgr_flush(struct lima_ctx_mgr *mgr, long timeout)
+{
+	struct lima_ctx *ctx;
+	unsigned long id;
+
+	mutex_lock(&mgr->lock);
+	xa_for_each(&mgr->handles, id, ctx) {
+		for (int i = 0; i < lima_pipe_num; i++) {
+			struct lima_sched_context *context = &ctx->context[i];
+			struct drm_sched_entity *entity = &context->base;
+
+			timeout = drm_sched_entity_flush(entity, timeout);
+		}
+	}
+	mutex_unlock(&mgr->lock);
+	return timeout;
+}
diff --git a/drivers/gpu/drm/lima/lima_ctx.h b/drivers/gpu/drm/lima/lima_ctx.h
index 5b1063ce968b..ff133db6ae4c 100644
--- a/drivers/gpu/drm/lima/lima_ctx.h
+++ b/drivers/gpu/drm/lima/lima_ctx.h
@@ -30,5 +30,6 @@ struct lima_ctx *lima_ctx_get(struct lima_ctx_mgr *mgr, u32 id);
 void lima_ctx_put(struct lima_ctx *ctx);
 void lima_ctx_mgr_init(struct lima_ctx_mgr *mgr);
 void lima_ctx_mgr_fini(struct lima_ctx_mgr *mgr);
+long lima_ctx_mgr_flush(struct lima_ctx_mgr *mgr, long timeout);
 
 #endif
diff --git a/drivers/gpu/drm/lima/lima_drv.c b/drivers/gpu/drm/lima/lima_drv.c
index 11ace5cebf4c..08169b0d9c28 100644
--- a/drivers/gpu/drm/lima/lima_drv.c
+++ b/drivers/gpu/drm/lima/lima_drv.c
@@ -254,7 +254,22 @@ static const struct drm_ioctl_desc lima_drm_driver_ioctls[] = {
 	DRM_IOCTL_DEF_DRV(LIMA_CTX_FREE, lima_ioctl_ctx_free, DRM_RENDER_ALLOW),
 };
 
-DEFINE_DRM_GEM_FOPS(lima_drm_driver_fops);
+static int lima_drm_driver_flush(struct file *filp, fl_owner_t id)
+{
+	struct drm_file *file = filp->private_data;
+	struct lima_drm_priv *priv = file->driver_priv;
+	long timeout = MAX_WAIT_SCHED_ENTITY_Q_EMPTY;
+
+	timeout = lima_ctx_mgr_flush(&priv->ctx_mgr, timeout);
+
+	return timeout >= 0 ? 0 : timeout;
+}
+
+static const struct file_operations lima_drm_driver_fops = {
+	.owner = THIS_MODULE,
+	.flush = lima_drm_driver_flush,
+	DRM_GEM_FOPS,
+};
 
 /*
  * Changelog:
-- 
2.49.0