diff options
Diffstat (limited to 'drivers/dma-buf/sw_sync.c')
-rw-r--r-- | drivers/dma-buf/sw_sync.c | 421 |
1 files changed, 421 insertions, 0 deletions
diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c new file mode 100644 index 000000000..81ba4eb34 --- /dev/null +++ b/drivers/dma-buf/sw_sync.c @@ -0,0 +1,421 @@ +/* + * 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_create_fence_data 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_create_fence_data + * @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 dma_fence_ops timeline_fence_ops; + +static inline struct sync_pt *dma_fence_to_sync_pt(struct dma_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. + */ +static 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 = dma_fence_context_alloc(1); + strlcpy(obj->name, name, sizeof(obj->name)); + + obj->pt_tree = RB_ROOT; + INIT_LIST_HEAD(&obj->pt_list); + spin_lock_init(&obj->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); +} + +static const char *timeline_fence_get_driver_name(struct dma_fence *fence) +{ + return "sw_sync"; +} + +static const char *timeline_fence_get_timeline_name(struct dma_fence *fence) +{ + struct sync_timeline *parent = dma_fence_parent(fence); + + return parent->name; +} + +static void timeline_fence_release(struct dma_fence *fence) +{ + struct sync_pt *pt = dma_fence_to_sync_pt(fence); + struct sync_timeline *parent = dma_fence_parent(fence); + unsigned long flags; + + spin_lock_irqsave(fence->lock, flags); + if (!list_empty(&pt->link)) { + list_del(&pt->link); + rb_erase(&pt->node, &parent->pt_tree); + } + spin_unlock_irqrestore(fence->lock, flags); + + sync_timeline_put(parent); + dma_fence_free(fence); +} + +static bool timeline_fence_signaled(struct dma_fence *fence) +{ + struct sync_timeline *parent = dma_fence_parent(fence); + + return !__dma_fence_is_later(fence->seqno, parent->value); +} + +static bool timeline_fence_enable_signaling(struct dma_fence *fence) +{ + return true; +} + +static void timeline_fence_value_str(struct dma_fence *fence, + char *str, int size) +{ + snprintf(str, size, "%d", fence->seqno); +} + +static void timeline_fence_timeline_value_str(struct dma_fence *fence, + char *str, int size) +{ + struct sync_timeline *parent = dma_fence_parent(fence); + + snprintf(str, size, "%d", parent->value); +} + +static const struct dma_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, + .release = timeline_fence_release, + .fence_value_str = timeline_fence_value_str, + .timeline_value_str = timeline_fence_timeline_value_str, +}; + +/** + * 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) +{ + struct sync_pt *pt, *next; + + trace_sync_timeline(obj); + + spin_lock_irq(&obj->lock); + + obj->value += inc; + + list_for_each_entry_safe(pt, next, &obj->pt_list, link) { + if (!timeline_fence_signaled(&pt->base)) + break; + + list_del_init(&pt->link); + rb_erase(&pt->node, &obj->pt_tree); + + /* + * A signal callback may release the last reference to this + * fence, causing it to be freed. That operation has to be + * last to avoid a use after free inside this loop, and must + * be after we remove the fence from the timeline in order to + * prevent deadlocking on timeline->lock inside + * timeline_fence_release(). + */ + dma_fence_signal_locked(&pt->base); + } + + spin_unlock_irq(&obj->lock); +} + +/** + * sync_pt_create() - creates a sync pt + * @obj: parent sync_timeline + * @value: value of the fence + * + * Creates a new sync_pt (fence) 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, + unsigned int value) +{ + struct sync_pt *pt; + + pt = kzalloc(sizeof(*pt), GFP_KERNEL); + if (!pt) + return NULL; + + sync_timeline_get(obj); + dma_fence_init(&pt->base, &timeline_fence_ops, &obj->lock, + obj->context, value); + INIT_LIST_HEAD(&pt->link); + + spin_lock_irq(&obj->lock); + if (!dma_fence_is_signaled_locked(&pt->base)) { + struct rb_node **p = &obj->pt_tree.rb_node; + struct rb_node *parent = NULL; + + while (*p) { + struct sync_pt *other; + int cmp; + + parent = *p; + other = rb_entry(parent, typeof(*pt), node); + cmp = value - other->base.seqno; + if (cmp > 0) { + p = &parent->rb_right; + } else if (cmp < 0) { + p = &parent->rb_left; + } else { + if (dma_fence_get_rcu(&other->base)) { + sync_timeline_put(obj); + kfree(pt); + pt = other; + goto unlock; + } + p = &parent->rb_left; + } + } + rb_link_node(&pt->node, parent, p); + rb_insert_color(&pt->node, &obj->pt_tree); + + parent = rb_next(&pt->node); + list_add_tail(&pt->link, + parent ? &rb_entry(parent, typeof(*pt), node)->link : &obj->pt_list); + } +unlock: + spin_unlock_irq(&obj->lock); + + return pt; +} + +/* + * *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; + struct sync_pt *pt, *next; + + spin_lock_irq(&obj->lock); + + list_for_each_entry_safe(pt, next, &obj->pt_list, link) { + dma_fence_set_error(&pt->base, -ENOENT); + dma_fence_signal_locked(&pt->base); + } + + spin_unlock_irq(&obj->lock); + + 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, data.value); + if (!pt) { + err = -ENOMEM; + goto err; + } + + sync_file = sync_file_create(&pt->base); + dma_fence_put(&pt->base); + if (!sync_file) { + 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; + + while (value > INT_MAX) { + sync_timeline_signal(obj, INT_MAX); + value -= INT_MAX; + } + + 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, +}; |