dma-buf/sw_sync: de-stage SW_SYNC

SW_SYNC allows to run tests on the sync_file framework via debugfs on

<debugfs>/sync/sw_sync

Opening and closing the file triggers creation and release of a sync
timeline. To create fences on this timeline the SW_SYNC_IOC_CREATE_FENCE
ioctl should be used. To increment the timeline value use SW_SYNC_IOC_INC.

Also it exports Sync information on

<debugfs>/sync/info

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 375 insertions, 0 deletions

diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c
new file mode 100644
index 000000000000..62e8e6dc7953
--- /dev/null
+++ b/drivers/dma-buf/sw_sync.c
@@ -0,0 +1,375 @@
+/*
+ * Sync File validation framework
+ *
+ * Copyright (C) 2012 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/sync_file.h>
+
+#include "sync_debug.h"
+
+#define CREATE_TRACE_POINTS
+#include "sync_trace.h"
+
+/*
+ * SW SYNC validation framework
+ *
+ * A sync object driver that uses a 32bit counter to coordinate
+ * synchronization.  Useful when there is no hardware primitive backing
+ * the synchronization.
+ *
+ * To start the framework just open:
+ *
+ * <debugfs>/sync/sw_sync
+ *
+ * That will create a sync timeline, all fences created under this timeline
+ * file descriptor will belong to the this timeline.
+ *
+ * The 'sw_sync' file can be opened many times as to create different
+ * timelines.
+ *
+ * Fences can be created with SW_SYNC_IOC_CREATE_FENCE ioctl with struct
+ * sw_sync_ioctl_create_fence as parameter.
+ *
+ * To increment the timeline counter, SW_SYNC_IOC_INC ioctl should be used
+ * with the increment as u32. This will update the last signaled value
+ * from the timeline and signal any fence that has a seqno smaller or equal
+ * to it.
+ *
+ * struct sw_sync_ioctl_create_fence
+ * @value:	the seqno to initialise the fence with
+ * @name:	the name of the new sync point
+ * @fence:	return the fd of the new sync_file with the created fence
+ */
+struct sw_sync_create_fence_data {
+	__u32	value;
+	char	name[32];
+	__s32	fence; /* fd of new fence */
+};
+
+#define SW_SYNC_IOC_MAGIC	'W'
+
+#define SW_SYNC_IOC_CREATE_FENCE	_IOWR(SW_SYNC_IOC_MAGIC, 0,\
+		struct sw_sync_create_fence_data)
+
+#define SW_SYNC_IOC_INC			_IOW(SW_SYNC_IOC_MAGIC, 1, __u32)
+
+static const struct fence_ops timeline_fence_ops;
+
+static inline struct sync_pt *fence_to_sync_pt(struct fence *fence)
+{
+	if (fence->ops != &timeline_fence_ops)
+		return NULL;
+	return container_of(fence, struct sync_pt, base);
+}
+
+/**
+ * sync_timeline_create() - creates a sync object
+ * @name:	sync_timeline name
+ *
+ * Creates a new sync_timeline. Returns the sync_timeline object or NULL in
+ * case of error.
+ */
+struct sync_timeline *sync_timeline_create(const char *name)
+{
+	struct sync_timeline *obj;
+
+	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+	if (!obj)
+		return NULL;
+
+	kref_init(&obj->kref);
+	obj->context = fence_context_alloc(1);
+	strlcpy(obj->name, name, sizeof(obj->name));
+
+	INIT_LIST_HEAD(&obj->child_list_head);
+	INIT_LIST_HEAD(&obj->active_list_head);
+	spin_lock_init(&obj->child_list_lock);
+
+	sync_timeline_debug_add(obj);
+
+	return obj;
+}
+
+static void sync_timeline_free(struct kref *kref)
+{
+	struct sync_timeline *obj =
+		container_of(kref, struct sync_timeline, kref);
+
+	sync_timeline_debug_remove(obj);
+
+	kfree(obj);
+}
+
+static void sync_timeline_get(struct sync_timeline *obj)
+{
+	kref_get(&obj->kref);
+}
+
+static void sync_timeline_put(struct sync_timeline *obj)
+{
+	kref_put(&obj->kref, sync_timeline_free);
+}
+
+/**
+ * sync_timeline_signal() - signal a status change on a sync_timeline
+ * @obj:	sync_timeline to signal
+ * @inc:	num to increment on timeline->value
+ *
+ * A sync implementation should call this any time one of it's fences
+ * has signaled or has an error condition.
+ */
+static void sync_timeline_signal(struct sync_timeline *obj, unsigned int inc)
+{
+	unsigned long flags;
+	struct sync_pt *pt, *next;
+
+	trace_sync_timeline(obj);
+
+	spin_lock_irqsave(&obj->child_list_lock, flags);
+
+	obj->value += inc;
+
+	list_for_each_entry_safe(pt, next, &obj->active_list_head,
+				 active_list) {
+		if (fence_is_signaled_locked(&pt->base))
+			list_del_init(&pt->active_list);
+	}
+
+	spin_unlock_irqrestore(&obj->child_list_lock, flags);
+}
+
+/**
+ * sync_pt_create() - creates a sync pt
+ * @parent:	fence's parent sync_timeline
+ * @size:	size to allocate for this pt
+ * @inc:	value of the fence
+ *
+ * Creates a new sync_pt as a child of @parent.  @size bytes will be
+ * allocated allowing for implementation specific data to be kept after
+ * the generic sync_timeline struct. Returns the sync_pt object or
+ * NULL in case of error.
+ */
+static struct sync_pt *sync_pt_create(struct sync_timeline *obj, int size,
+			     unsigned int value)
+{
+	unsigned long flags;
+	struct sync_pt *pt;
+
+	if (size < sizeof(*pt))
+		return NULL;
+
+	pt = kzalloc(size, GFP_KERNEL);
+	if (!pt)
+		return NULL;
+
+	spin_lock_irqsave(&obj->child_list_lock, flags);
+	sync_timeline_get(obj);
+	fence_init(&pt->base, &timeline_fence_ops, &obj->child_list_lock,
+		   obj->context, value);
+	list_add_tail(&pt->child_list, &obj->child_list_head);
+	INIT_LIST_HEAD(&pt->active_list);
+	spin_unlock_irqrestore(&obj->child_list_lock, flags);
+	return pt;
+}
+
+static const char *timeline_fence_get_driver_name(struct fence *fence)
+{
+	return "sw_sync";
+}
+
+static const char *timeline_fence_get_timeline_name(struct fence *fence)
+{
+	struct sync_timeline *parent = fence_parent(fence);
+
+	return parent->name;
+}
+
+static void timeline_fence_release(struct fence *fence)
+{
+	struct sync_pt *pt = fence_to_sync_pt(fence);
+	struct sync_timeline *parent = fence_parent(fence);
+	unsigned long flags;
+
+	spin_lock_irqsave(fence->lock, flags);
+	list_del(&pt->child_list);
+	if (!list_empty(&pt->active_list))
+		list_del(&pt->active_list);
+	spin_unlock_irqrestore(fence->lock, flags);
+
+	sync_timeline_put(parent);
+	fence_free(fence);
+}
+
+static bool timeline_fence_signaled(struct fence *fence)
+{
+	struct sync_timeline *parent = fence_parent(fence);
+
+	return (fence->seqno > parent->value) ? false : true;
+}
+
+static bool timeline_fence_enable_signaling(struct fence *fence)
+{
+	struct sync_pt *pt = fence_to_sync_pt(fence);
+	struct sync_timeline *parent = fence_parent(fence);
+
+	if (timeline_fence_signaled(fence))
+		return false;
+
+	list_add_tail(&pt->active_list, &parent->active_list_head);
+	return true;
+}
+
+static void timeline_fence_value_str(struct fence *fence,
+				    char *str, int size)
+{
+	snprintf(str, size, "%d", fence->seqno);
+}
+
+static void timeline_fence_timeline_value_str(struct fence *fence,
+					     char *str, int size)
+{
+	struct sync_timeline *parent = fence_parent(fence);
+
+	snprintf(str, size, "%d", parent->value);
+}
+
+static const struct fence_ops timeline_fence_ops = {
+	.get_driver_name = timeline_fence_get_driver_name,
+	.get_timeline_name = timeline_fence_get_timeline_name,
+	.enable_signaling = timeline_fence_enable_signaling,
+	.signaled = timeline_fence_signaled,
+	.wait = fence_default_wait,
+	.release = timeline_fence_release,
+	.fence_value_str = timeline_fence_value_str,
+	.timeline_value_str = timeline_fence_timeline_value_str,
+};
+
+/*
+ * *WARNING*
+ *
+ * improper use of this can result in deadlocking kernel drivers from userspace.
+ */
+
+/* opening sw_sync create a new sync obj */
+static int sw_sync_debugfs_open(struct inode *inode, struct file *file)
+{
+	struct sync_timeline *obj;
+	char task_comm[TASK_COMM_LEN];
+
+	get_task_comm(task_comm, current);
+
+	obj = sync_timeline_create(task_comm);
+	if (!obj)
+		return -ENOMEM;
+
+	file->private_data = obj;
+
+	return 0;
+}
+
+static int sw_sync_debugfs_release(struct inode *inode, struct file *file)
+{
+	struct sync_timeline *obj = file->private_data;
+
+	smp_wmb();
+
+	sync_timeline_put(obj);
+	return 0;
+}
+
+static long sw_sync_ioctl_create_fence(struct sync_timeline *obj,
+				       unsigned long arg)
+{
+	int fd = get_unused_fd_flags(O_CLOEXEC);
+	int err;
+	struct sync_pt *pt;
+	struct sync_file *sync_file;
+	struct sw_sync_create_fence_data data;
+
+	if (fd < 0)
+		return fd;
+
+	if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
+		err = -EFAULT;
+		goto err;
+	}
+
+	pt = sync_pt_create(obj, sizeof(*pt), data.value);
+	if (!pt) {
+		err = -ENOMEM;
+		goto err;
+	}
+
+	sync_file = sync_file_create(&pt->base);
+	if (!sync_file) {
+		fence_put(&pt->base);
+		err = -ENOMEM;
+		goto err;
+	}
+
+	data.fence = fd;
+	if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
+		fput(sync_file->file);
+		err = -EFAULT;
+		goto err;
+	}
+
+	fd_install(fd, sync_file->file);
+
+	return 0;
+
+err:
+	put_unused_fd(fd);
+	return err;
+}
+
+static long sw_sync_ioctl_inc(struct sync_timeline *obj, unsigned long arg)
+{
+	u32 value;
+
+	if (copy_from_user(&value, (void __user *)arg, sizeof(value)))
+		return -EFAULT;
+
+	sync_timeline_signal(obj, value);
+
+	return 0;
+}
+
+static long sw_sync_ioctl(struct file *file, unsigned int cmd,
+			  unsigned long arg)
+{
+	struct sync_timeline *obj = file->private_data;
+
+	switch (cmd) {
+	case SW_SYNC_IOC_CREATE_FENCE:
+		return sw_sync_ioctl_create_fence(obj, arg);
+
+	case SW_SYNC_IOC_INC:
+		return sw_sync_ioctl_inc(obj, arg);
+
+	default:
+		return -ENOTTY;
+	}
+}
+
+const struct file_operations sw_sync_debugfs_fops = {
+	.open           = sw_sync_debugfs_open,
+	.release        = sw_sync_debugfs_release,
+	.unlocked_ioctl = sw_sync_ioctl,
+	.compat_ioctl	= sw_sync_ioctl,
+};