syncobj wait patch

syncobj wait patch

[Dave Airlie]

I'm going to push the syncobj and sync_file interaction 
patches into drm-next, but I think this patch still needs
a few more trips on the merry go round.

I've decided to read Daniel's ioctl guide, use sec/nsec,
and convert to timespec internally then use timespec as much
as possible.

Dave.

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[PATCH] drm/syncobj: add sync obj wait interface. (v5)

[Dave Airlie]

From: Dave Airlie <airlied@redhat.com>

This interface will allow sync object to be used to back
Vulkan fences. This API is pretty much the vulkan fence waiting
API, and I've ported the code from amdgpu.

v2: accept relative timeout, pass remaining time back
to userspace.
v3: return to absolute timeouts.
v4: absolute zero = poll,
    rewrite any/all code to have same operation for arrays
    return -EINVAL for 0 fences.
v4.1: fixup fences allocation check, use u64_to_user_ptr
v5: move to sec/nsec, and use timespec64 for calcs.

Signed-off-by: Dave Airlie <airlied@redhat.com>
---
 drivers/gpu/drm/drm_internal.h |   2 +
 drivers/gpu/drm/drm_ioctl.c    |   2 +
 drivers/gpu/drm/drm_syncobj.c  | 142 +++++++++++++++++++++++++++++++++++++++++
 include/uapi/drm/drm.h         |  13 ++++
 4 files changed, 159 insertions(+)

diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index 3fdef2c..53e3f6b 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -156,3 +156,5 @@ int drm_syncobj_handle_to_fd_ioctl(struct drm_device *dev, void *data,
 				   struct drm_file *file_private);
 int drm_syncobj_fd_to_handle_ioctl(struct drm_device *dev, void *data,
 				   struct drm_file *file_private);
+int drm_syncobj_wait_ioctl(struct drm_device *dev, void *data,
+			   struct drm_file *file_private);
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index f1e5681..385ce74 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -657,6 +657,8 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
 		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE, drm_syncobj_fd_to_handle_ioctl,
 		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_WAIT, drm_syncobj_wait_ioctl,
+		      DRM_UNLOCKED|DRM_RENDER_ALLOW),
 };
 
 #define DRM_CORE_IOCTL_COUNT	ARRAY_SIZE( drm_ioctls )
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 89441bc..3b77125 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -1,5 +1,7 @@
 /*
  * Copyright 2017 Red Hat
+ * Parts ported from amdgpu (fence wait code).
+ * Copyright 2016 Advanced Micro Devices, Inc.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -31,6 +33,9 @@
  * that contain an optional fence. The fence can be updated with a new
  * fence, or be NULL.
  *
+ * syncobj's can be waited upon, where it will wait for the underlying
+ * fence.
+ *
  * syncobj's can be export to fd's and back, these fd's are opaque and
  * have no other use case, except passing the syncobj between processes.
  *
@@ -451,3 +456,140 @@ drm_syncobj_fd_to_handle_ioctl(struct drm_device *dev, void *data,
 	return drm_syncobj_fd_to_handle(file_private, args->fd,
 					&args->handle);
 }
+
+
+/**
+ * drm_timeout_abs_to_jiffies - calculate jiffies timeout from absolute value
+ *
+ * @timeout_sec: timeout sec component, 0 for poll
+ * @timeout_nsec: timeout nsec component in ns, 0 for poll
+ * both must be 0 for poll.
+ *
+ * Calculate the timeout in jiffies from an absolute time in sec/nsec.
+ */
+static unsigned long drm_timeout_abs_to_jiffies(int64_t timeout_sec, uint64_t timeout_nsec)
+{
+	struct timespec64 abs_timeout, timeout, max_jiffy_timespec;
+	unsigned long timeout_jiffies;
+
+	/* make 0 timeout means poll - absolute 0 doesn't seem valid */
+	if (timeout_sec == 0 && timeout_nsec == 0)
+		return 0;
+
+	abs_timeout.tv_sec = timeout_sec;
+	abs_timeout.tv_nsec = timeout_nsec;
+
+	/* clamp timeout if it's to large */
+	if (!timespec64_valid_strict(&abs_timeout))
+		return MAX_SCHEDULE_TIMEOUT - 1;
+
+	timeout = timespec64_sub(abs_timeout, ktime_to_timespec64(ktime_get()));
+	if (!timespec64_valid(&timeout))
+		return 0;
+
+	jiffies_to_timespec64(MAX_JIFFY_OFFSET, &max_jiffy_timespec);
+	if (timespec64_compare(&timeout, &max_jiffy_timespec) >= 0)
+		return MAX_SCHEDULE_TIMEOUT - 1;
+
+	timeout_jiffies = timespec64_to_jiffies(&timeout);
+	/*  clamp timeout to avoid infinite timeout */
+	if (timeout_jiffies >= MAX_SCHEDULE_TIMEOUT)
+		return MAX_SCHEDULE_TIMEOUT - 1;
+
+	return timeout_jiffies + 1;
+}
+
+static int drm_syncobj_wait_fences(struct drm_device *dev,
+				   struct drm_file *file_private,
+				   struct drm_syncobj_wait *wait,
+				   struct dma_fence **fences)
+{
+	unsigned long timeout = drm_timeout_abs_to_jiffies(wait->timeout_sec, wait->timeout_nsec);
+	int ret = 0;
+	uint32_t first = ~0;
+
+	if (wait->flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL) {
+		int i;
+		for (i = 0; i < wait->count_handles; i++) {
+			ret = dma_fence_wait_timeout(fences[i], true, timeout);
+
+			if (ret < 0)
+				return ret;
+			if (ret == 0)
+				break;
+			timeout = ret;
+		}
+		first = 0;
+	} else {
+		ret = dma_fence_wait_any_timeout(fences,
+						 wait->count_handles,
+						 true, timeout,
+						 &first);
+	}
+
+	if (ret < 0)
+		return ret;
+
+	wait->out_status = (ret > 0);
+	wait->first_signaled = first;
+	return 0;
+}
+
+int
+drm_syncobj_wait_ioctl(struct drm_device *dev, void *data,
+		       struct drm_file *file_private)
+{
+	struct drm_syncobj_wait *args = data;
+	uint32_t *handles;
+	struct dma_fence **fences;
+	int ret = 0;
+	int i;
+
+	if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
+		return -ENODEV;
+
+	if (args->flags != 0 && args->flags != DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL)
+		return -EINVAL;
+
+	if (args->count_handles == 0)
+		return -EINVAL;
+
+	/* Get the handles from userspace */
+	handles = kmalloc_array(args->count_handles, sizeof(uint32_t),
+				GFP_KERNEL);
+	if (handles == NULL)
+		return -ENOMEM;
+
+	if (copy_from_user(handles,
+			   u64_to_user_ptr(args->handles),
+			   sizeof(uint32_t) * args->count_handles)) {
+		ret = -EFAULT;
+		goto err_free_handles;
+	}
+
+	fences = kcalloc(args->count_handles,
+			 sizeof(struct dma_fence *), GFP_KERNEL);
+	if (!fences) {
+		ret = -ENOMEM;
+		goto err_free_handles;
+	}
+
+	for (i = 0; i < args->count_handles; i++) {
+		ret = drm_syncobj_fence_get(file_private, handles[i],
+					    &fences[i]);
+		if (ret)
+			goto err_free_fence_array;
+	}
+
+	ret = drm_syncobj_wait_fences(dev, file_private,
+				      args, fences);
+
+err_free_fence_array:
+	for (i = 0; i < args->count_handles; i++)
+		dma_fence_put(fences[i]);
+	kfree(fences);
+err_free_handles:
+	kfree(handles);
+
+	return ret;
+}
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
index 101593a..14363a6 100644
--- a/include/uapi/drm/drm.h
+++ b/include/uapi/drm/drm.h
@@ -718,6 +718,18 @@ struct drm_syncobj_handle {
 	__u32 pad;
 };
 
+#define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL (1 << 0)
+struct drm_syncobj_wait {
+	__u64 handles;
+	/* absolute timeout */
+	__s64 timeout_sec;
+	__s64 timeout_nsec;
+	__u32 count_handles;
+	__u32 flags;
+	__u32 out_status;
+	__u32 first_signaled; /* on valid when not waiting all */
+};
+
 #if defined(__cplusplus)
 }
 #endif
@@ -840,6 +852,7 @@ extern "C" {
 #define DRM_IOCTL_SYNCOBJ_DESTROY	DRM_IOWR(0xC0, struct drm_syncobj_destroy)
 #define DRM_IOCTL_SYNCOBJ_HANDLE_TO_FD	DRM_IOWR(0xC1, struct drm_syncobj_handle)
 #define DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE	DRM_IOWR(0xC2, struct drm_syncobj_handle)
+#define DRM_IOCTL_SYNCOBJ_WAIT		DRM_IOWR(0xC3, struct drm_syncobj_wait)
 
 /**
  * Device specific ioctls should only be in their respective headers
-- 
2.9.4

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