drivers/dma-buf/sw_sync.c

   1 /*
   2  * Sync File validation framework
   3  *
   4  * Copyright (C) 2012 Google, Inc.
   5  *
   6  * This software is licensed under the terms of the GNU General Public
   7  * License version 2, as published by the Free Software Foundation, and
   8  * may be copied, distributed, and modified under those terms.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  */
  16
  17 #include <linux/file.h>
  18 #include <linux/fs.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/slab.h>
  21 #include <linux/sync_file.h>
  22
  23 #include "sync_debug.h"
  24
  25 #define CREATE_TRACE_POINTS
  26 #include "sync_trace.h"
  27
  28 /*
  29  * SW SYNC validation framework
  30  *
  31  * A sync object driver that uses a 32bit counter to coordinate
  32  * synchronization.  Useful when there is no hardware primitive backing
  33  * the synchronization.
  34  *
  35  * To start the framework just open:
  36  *
  37  * <debugfs>/sync/sw_sync
  38  *
  39  * That will create a sync timeline, all fences created under this timeline
  40  * file descriptor will belong to the this timeline.
  41  *
  42  * The 'sw_sync' file can be opened many times as to create different
  43  * timelines.
  44  *
  45  * Fences can be created with SW_SYNC_IOC_CREATE_FENCE ioctl with struct
  46  * sw_sync_ioctl_create_fence as parameter.
  47  *
  48  * To increment the timeline counter, SW_SYNC_IOC_INC ioctl should be used
  49  * with the increment as u32. This will update the last signaled value
  50  * from the timeline and signal any fence that has a seqno smaller or equal
  51  * to it.
  52  *
  53  * struct sw_sync_ioctl_create_fence
  54  * @value:      the seqno to initialise the fence with
  55  * @name:       the name of the new sync point
  56  * @fence:      return the fd of the new sync_file with the created fence
  57  */
  58 struct sw_sync_create_fence_data {
  59         __u32   value;
  60         char    name[32];
  61         __s32   fence; /* fd of new fence */
  62 };
  63
  64 #define SW_SYNC_IOC_MAGIC       'W'
  65
  66 #define SW_SYNC_IOC_CREATE_FENCE        _IOWR(SW_SYNC_IOC_MAGIC, 0,\
  67                 struct sw_sync_create_fence_data)
  68
  69 #define SW_SYNC_IOC_INC                 _IOW(SW_SYNC_IOC_MAGIC, 1, __u32)
  70
  71 static const struct fence_ops timeline_fence_ops;
  72
  73 static inline struct sync_pt *fence_to_sync_pt(struct fence *fence)
  74 {
  75         if (fence->ops != &timeline_fence_ops)
  76                 return NULL;
  77         return container_of(fence, struct sync_pt, base);
  78 }
  79
  80 /**
  81  * sync_timeline_create() - creates a sync object
  82  * @name:       sync_timeline name
  83  *
  84  * Creates a new sync_timeline. Returns the sync_timeline object or NULL in
  85  * case of error.
  86  */
  87 struct sync_timeline *sync_timeline_create(const char *name)
  88 {
  89         struct sync_timeline *obj;
  90
  91         obj = kzalloc(sizeof(*obj), GFP_KERNEL);
  92         if (!obj)
  93                 return NULL;
  94
  95         kref_init(&obj->kref);
  96         obj->context = fence_context_alloc(1);
  97         strlcpy(obj->name, name, sizeof(obj->name));
  98
  99         INIT_LIST_HEAD(&obj->child_list_head);
 100         INIT_LIST_HEAD(&obj->active_list_head);
 101         spin_lock_init(&obj->child_list_lock);
 102
 103         sync_timeline_debug_add(obj);
 104
 105         return obj;
 106 }
 107
 108 static void sync_timeline_free(struct kref *kref)
 109 {
 110         struct sync_timeline *obj =
 111                 container_of(kref, struct sync_timeline, kref);
 112
 113         sync_timeline_debug_remove(obj);
 114
 115         kfree(obj);
 116 }
 117
 118 static void sync_timeline_get(struct sync_timeline *obj)
 119 {
 120         kref_get(&obj->kref);
 121 }
 122
 123 static void sync_timeline_put(struct sync_timeline *obj)
 124 {
 125         kref_put(&obj->kref, sync_timeline_free);
 126 }
 127
 128 /**
 129  * sync_timeline_signal() - signal a status change on a sync_timeline
 130  * @obj:        sync_timeline to signal
 131  * @inc:        num to increment on timeline->value
 132  *
 133  * A sync implementation should call this any time one of it's fences
 134  * has signaled or has an error condition.
 135  */
 136 static void sync_timeline_signal(struct sync_timeline *obj, unsigned int inc)
 137 {
 138         unsigned long flags;
 139         struct sync_pt *pt, *next;
 140
 141         trace_sync_timeline(obj);
 142
 143         spin_lock_irqsave(&obj->child_list_lock, flags);
 144
 145         obj->value += inc;
 146
 147         list_for_each_entry_safe(pt, next, &obj->active_list_head,
 148                                  active_list) {
 149                 if (fence_is_signaled_locked(&pt->base))
 150                         list_del_init(&pt->active_list);
 151         }
 152
 153         spin_unlock_irqrestore(&obj->child_list_lock, flags);
 154 }
 155
 156 /**
 157  * sync_pt_create() - creates a sync pt
 158  * @parent:     fence's parent sync_timeline
 159  * @size:       size to allocate for this pt
 160  * @inc:        value of the fence
 161  *
 162  * Creates a new sync_pt as a child of @parent.  @size bytes will be
 163  * allocated allowing for implementation specific data to be kept after
 164  * the generic sync_timeline struct. Returns the sync_pt object or
 165  * NULL in case of error.
 166  */
 167 static struct sync_pt *sync_pt_create(struct sync_timeline *obj, int size,
 168                              unsigned int value)
 169 {
 170         unsigned long flags;
 171         struct sync_pt *pt;
 172
 173         if (size < sizeof(*pt))
 174                 return NULL;
 175
 176         pt = kzalloc(size, GFP_KERNEL);
 177         if (!pt)
 178                 return NULL;
 179
 180         spin_lock_irqsave(&obj->child_list_lock, flags);
 181         sync_timeline_get(obj);
 182         fence_init(&pt->base, &timeline_fence_ops, &obj->child_list_lock,
 183                    obj->context, value);
 184         list_add_tail(&pt->child_list, &obj->child_list_head);
 185         INIT_LIST_HEAD(&pt->active_list);
 186         spin_unlock_irqrestore(&obj->child_list_lock, flags);
 187         return pt;
 188 }
 189
 190 static const char *timeline_fence_get_driver_name(struct fence *fence)
 191 {
 192         return "sw_sync";
 193 }
 194
 195 static const char *timeline_fence_get_timeline_name(struct fence *fence)
 196 {
 197         struct sync_timeline *parent = fence_parent(fence);
 198
 199         return parent->name;
 200 }
 201
 202 static void timeline_fence_release(struct fence *fence)
 203 {
 204         struct sync_pt *pt = fence_to_sync_pt(fence);
 205         struct sync_timeline *parent = fence_parent(fence);
 206         unsigned long flags;
 207
 208         spin_lock_irqsave(fence->lock, flags);
 209         list_del(&pt->child_list);
 210         if (!list_empty(&pt->active_list))
 211                 list_del(&pt->active_list);
 212         spin_unlock_irqrestore(fence->lock, flags);
 213
 214         sync_timeline_put(parent);
 215         fence_free(fence);
 216 }
 217
 218 static bool timeline_fence_signaled(struct fence *fence)
 219 {
 220         struct sync_timeline *parent = fence_parent(fence);
 221
 222         return (fence->seqno > parent->value) ? false : true;
 223 }
 224
 225 static bool timeline_fence_enable_signaling(struct fence *fence)
 226 {
 227         struct sync_pt *pt = fence_to_sync_pt(fence);
 228         struct sync_timeline *parent = fence_parent(fence);
 229
 230         if (timeline_fence_signaled(fence))
 231                 return false;
 232
 233         list_add_tail(&pt->active_list, &parent->active_list_head);
 234         return true;
 235 }
 236
 237 static void timeline_fence_value_str(struct fence *fence,
 238                                     char *str, int size)
 239 {
 240         snprintf(str, size, "%d", fence->seqno);
 241 }
 242
 243 static void timeline_fence_timeline_value_str(struct fence *fence,
 244                                              char *str, int size)
 245 {
 246         struct sync_timeline *parent = fence_parent(fence);
 247
 248         snprintf(str, size, "%d", parent->value);
 249 }
 250
 251 static const struct fence_ops timeline_fence_ops = {
 252         .get_driver_name = timeline_fence_get_driver_name,
 253         .get_timeline_name = timeline_fence_get_timeline_name,
 254         .enable_signaling = timeline_fence_enable_signaling,
 255         .signaled = timeline_fence_signaled,
 256         .wait = fence_default_wait,
 257         .release = timeline_fence_release,
 258         .fence_value_str = timeline_fence_value_str,
 259         .timeline_value_str = timeline_fence_timeline_value_str,
 260 };
 261
 262 /*
 263  * *WARNING*
 264  *
 265  * improper use of this can result in deadlocking kernel drivers from userspace.
 266  */
 267
 268 /* opening sw_sync create a new sync obj */
 269 static int sw_sync_debugfs_open(struct inode *inode, struct file *file)
 270 {
 271         struct sync_timeline *obj;
 272         char task_comm[TASK_COMM_LEN];
 273
 274         get_task_comm(task_comm, current);
 275
 276         obj = sync_timeline_create(task_comm);
 277         if (!obj)
 278                 return -ENOMEM;
 279
 280         file->private_data = obj;
 281
 282         return 0;
 283 }
 284
 285 static int sw_sync_debugfs_release(struct inode *inode, struct file *file)
 286 {
 287         struct sync_timeline *obj = file->private_data;
 288
 289         smp_wmb();
 290
 291         sync_timeline_put(obj);
 292         return 0;
 293 }
 294
 295 static long sw_sync_ioctl_create_fence(struct sync_timeline *obj,
 296                                        unsigned long arg)
 297 {
 298         int fd = get_unused_fd_flags(O_CLOEXEC);
 299         int err;
 300         struct sync_pt *pt;
 301         struct sync_file *sync_file;
 302         struct sw_sync_create_fence_data data;
 303
 304         if (fd < 0)
 305                 return fd;
 306
 307         if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
 308                 err = -EFAULT;
 309                 goto err;
 310         }
 311
 312         pt = sync_pt_create(obj, sizeof(*pt), data.value);
 313         if (!pt) {
 314                 err = -ENOMEM;
 315                 goto err;
 316         }
 317
 318         sync_file = sync_file_create(&pt->base);
 319         if (!sync_file) {
 320                 fence_put(&pt->base);
 321                 err = -ENOMEM;
 322                 goto err;
 323         }
 324
 325         data.fence = fd;
 326         if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
 327                 fput(sync_file->file);
 328                 err = -EFAULT;
 329                 goto err;
 330         }
 331
 332         fd_install(fd, sync_file->file);
 333
 334         return 0;
 335
 336 err:
 337         put_unused_fd(fd);
 338         return err;
 339 }
 340
 341 static long sw_sync_ioctl_inc(struct sync_timeline *obj, unsigned long arg)
 342 {
 343         u32 value;
 344
 345         if (copy_from_user(&value, (void __user *)arg, sizeof(value)))
 346                 return -EFAULT;
 347
 348         sync_timeline_signal(obj, value);
 349
 350         return 0;
 351 }
 352
 353 static long sw_sync_ioctl(struct file *file, unsigned int cmd,
 354                           unsigned long arg)
 355 {
 356         struct sync_timeline *obj = file->private_data;
 357
 358         switch (cmd) {
 359         case SW_SYNC_IOC_CREATE_FENCE:
 360                 return sw_sync_ioctl_create_fence(obj, arg);
 361
 362         case SW_SYNC_IOC_INC:
 363                 return sw_sync_ioctl_inc(obj, arg);
 364
 365         default:
 366                 return -ENOTTY;
 367         }
 368 }
 369
 370 const struct file_operations sw_sync_debugfs_fops = {
 371         .open           = sw_sync_debugfs_open,
 372         .release        = sw_sync_debugfs_release,
 373         .unlocked_ioctl = sw_sync_ioctl,
 374         .compat_ioctl   = sw_sync_ioctl,
 375 };