OSCL-LXR linux-6.0.1/​drivers/​dma-buf/​sw_sync.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Sync File validation framework
  *
  * Copyright (C) 2012 Google, Inc.
  */
 
 #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, fence->ops);
 }
 
 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, "%lld", 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   = compat_ptr_ioctl,
 };

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