From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 15 Jan 2018 09:06:43 +0000
Subject: drm/i915/fence: Separate timeout mechanism for awaiting on dma-fences
Git-commit: f255c1e91e333ba0bd177120748f4caf294b812b
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

As the timeout mechanism has grown more and more complicated, using
multiple deferred tasks and more than doubling the size of our struct,
split the two implementations to streamline the simpler no-timeout
callback variant.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180115090643.26696-2-chris@chris-wilson.co.uk

Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/i915/i915_sw_fence.c |   61 ++++++++++++++++++++++-------------
 1 file changed, 40 insertions(+), 21 deletions(-)

--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -365,18 +365,31 @@ int i915_sw_fence_await_sw_fence_gfp(str
 struct i915_sw_dma_fence_cb {
 	struct dma_fence_cb base;
 	struct i915_sw_fence *fence;
+};
+
+struct i915_sw_dma_fence_cb_timer {
+	struct i915_sw_dma_fence_cb base;
 	struct dma_fence *dma;
 	struct timer_list timer;
 	struct irq_work work;
 	struct rcu_head rcu;
 };
 
+static void dma_i915_sw_fence_wake(struct dma_fence *dma,
+				   struct dma_fence_cb *data)
+{
+	struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
+
+	i915_sw_fence_complete(cb->fence);
+	kfree(cb);
+}
+
 static void timer_i915_sw_fence_wake(struct timer_list *t)
 {
-	struct i915_sw_dma_fence_cb *cb = from_timer(cb, t, timer);
+	struct i915_sw_dma_fence_cb_timer *cb = from_timer(cb, t, timer);
 	struct i915_sw_fence *fence;
 
-	fence = xchg(&cb->fence, NULL);
+	fence = xchg(&cb->base.fence, NULL);
 	if (!fence)
 		return;
 
@@ -388,27 +401,24 @@ static void timer_i915_sw_fence_wake(str
 	i915_sw_fence_complete(fence);
 }
 
-static void dma_i915_sw_fence_wake(struct dma_fence *dma,
-				   struct dma_fence_cb *data)
+static void dma_i915_sw_fence_wake_timer(struct dma_fence *dma,
+					 struct dma_fence_cb *data)
 {
-	struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
+	struct i915_sw_dma_fence_cb_timer *cb =
+		container_of(data, typeof(*cb), base.base);
 	struct i915_sw_fence *fence;
 
-	fence = xchg(&cb->fence, NULL);
+	fence = xchg(&cb->base.fence, NULL);
 	if (fence)
 		i915_sw_fence_complete(fence);
 
-	if (cb->dma) {
-		irq_work_queue(&cb->work);
-		return;
-	}
-
-	kfree(cb);
+	irq_work_queue(&cb->work);
 }
 
 static void irq_i915_sw_fence_work(struct irq_work *wrk)
 {
-	struct i915_sw_dma_fence_cb *cb = container_of(wrk, typeof(*cb), work);
+	struct i915_sw_dma_fence_cb_timer *cb =
+		container_of(wrk, typeof(*cb), work);
 
 	del_timer_sync(&cb->timer);
 	dma_fence_put(cb->dma);
@@ -422,6 +432,7 @@ int i915_sw_fence_await_dma_fence(struct
 				  gfp_t gfp)
 {
 	struct i915_sw_dma_fence_cb *cb;
+	dma_fence_func_t func;
 	int ret;
 
 	debug_fence_assert(fence);
@@ -430,7 +441,10 @@ int i915_sw_fence_await_dma_fence(struct
 	if (dma_fence_is_signaled(dma))
 		return 0;
 
-	cb = kmalloc(sizeof(*cb), gfp);
+	cb = kmalloc(timeout ?
+		     sizeof(struct i915_sw_dma_fence_cb_timer) :
+		     sizeof(struct i915_sw_dma_fence_cb),
+		     gfp);
 	if (!cb) {
 		if (!gfpflags_allow_blocking(gfp))
 			return -ENOMEM;
@@ -441,21 +455,26 @@ int i915_sw_fence_await_dma_fence(struct
 	cb->fence = fence;
 	i915_sw_fence_await(fence);
 
-	cb->dma = NULL;
+	func = dma_i915_sw_fence_wake;
 	if (timeout) {
-		cb->dma = dma_fence_get(dma);
-		init_irq_work(&cb->work, irq_i915_sw_fence_work);
+		struct i915_sw_dma_fence_cb_timer *timer =
+			container_of(cb, typeof(*timer), base);
 
-		timer_setup(&cb->timer,
+		timer->dma = dma_fence_get(dma);
+		init_irq_work(&timer->work, irq_i915_sw_fence_work);
+
+		timer_setup(&timer->timer,
 			    timer_i915_sw_fence_wake, TIMER_IRQSAFE);
-		mod_timer(&cb->timer, round_jiffies_up(jiffies + timeout));
+		mod_timer(&timer->timer, round_jiffies_up(jiffies + timeout));
+
+		func = dma_i915_sw_fence_wake_timer;
 	}
 
-	ret = dma_fence_add_callback(dma, &cb->base, dma_i915_sw_fence_wake);
+	ret = dma_fence_add_callback(dma, &cb->base, func);
 	if (ret == 0) {
 		ret = 1;
 	} else {
-		dma_i915_sw_fence_wake(dma, &cb->base);
+		func(dma, &cb->base);
 		if (ret == -ENOENT) /* fence already signaled */
 			ret = 0;
 	}