drivers/media/media-request.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Media device request objects
   4  *
   5  * Copyright 2018 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
   6  * Copyright (C) 2018 Intel Corporation
   7  * Copyright (C) 2018 Google, Inc.
   8  *
   9  * Author: Hans Verkuil <hans.verkuil@cisco.com>
  10  * Author: Sakari Ailus <sakari.ailus@linux.intel.com>
  11  */
  12
  13 #include <linux/anon_inodes.h>
  14 #include <linux/file.h>
  15 #include <linux/refcount.h>
  16
  17 #include <media/media-device.h>
  18 #include <media/media-request.h>
  19
  20 static const char * const request_state[] = {
  21         [MEDIA_REQUEST_STATE_IDLE]       = "idle",
  22         [MEDIA_REQUEST_STATE_VALIDATING] = "validating",
  23         [MEDIA_REQUEST_STATE_QUEUED]     = "queued",
  24         [MEDIA_REQUEST_STATE_COMPLETE]   = "complete",
  25         [MEDIA_REQUEST_STATE_CLEANING]   = "cleaning",
  26         [MEDIA_REQUEST_STATE_UPDATING]   = "updating",
  27 };
  28
  29 static const char *
  30 media_request_state_str(enum media_request_state state)
  31 {
  32         BUILD_BUG_ON(ARRAY_SIZE(request_state) != NR_OF_MEDIA_REQUEST_STATE);
  33
  34         if (WARN_ON(state >= ARRAY_SIZE(request_state)))
  35                 return "invalid";
  36         return request_state[state];
  37 }
  38
  39 static void media_request_clean(struct media_request *req)
  40 {
  41         struct media_request_object *obj, *obj_safe;
  42
  43         /* Just a sanity check. No other code path is allowed to change this. */
  44         WARN_ON(req->state != MEDIA_REQUEST_STATE_CLEANING);
  45         WARN_ON(req->updating_count);
  46         WARN_ON(req->access_count);
  47
  48         list_for_each_entry_safe(obj, obj_safe, &req->objects, list) {
  49                 media_request_object_unbind(obj);
  50                 media_request_object_put(obj);
  51         }
  52
  53         req->updating_count = 0;
  54         req->access_count = 0;
  55         WARN_ON(req->num_incomplete_objects);
  56         req->num_incomplete_objects = 0;
  57         wake_up_interruptible_all(&req->poll_wait);
  58 }
  59
  60 static void media_request_release(struct kref *kref)
  61 {
  62         struct media_request *req =
  63                 container_of(kref, struct media_request, kref);
  64         struct media_device *mdev = req->mdev;
  65
  66         dev_dbg(mdev->dev, "request: release %s\n", req->debug_str);
  67
  68         /* No other users, no need for a spinlock */
  69         req->state = MEDIA_REQUEST_STATE_CLEANING;
  70
  71         media_request_clean(req);
  72
  73         if (mdev->ops->req_free)
  74                 mdev->ops->req_free(req);
  75         else
  76                 kfree(req);
  77 }
  78
  79 void media_request_put(struct media_request *req)
  80 {
  81         kref_put(&req->kref, media_request_release);
  82 }
  83 EXPORT_SYMBOL_GPL(media_request_put);
  84
  85 static int media_request_close(struct inode *inode, struct file *filp)
  86 {
  87         struct media_request *req = filp->private_data;
  88
  89         media_request_put(req);
  90         return 0;
  91 }
  92
  93 static __poll_t media_request_poll(struct file *filp,
  94                                    struct poll_table_struct *wait)
  95 {
  96         struct media_request *req = filp->private_data;
  97         unsigned long flags;
  98         __poll_t ret = 0;
  99
 100         if (!(poll_requested_events(wait) & EPOLLPRI))
 101                 return 0;
 102
 103         poll_wait(filp, &req->poll_wait, wait);
 104         spin_lock_irqsave(&req->lock, flags);
 105         if (req->state == MEDIA_REQUEST_STATE_COMPLETE) {
 106                 ret = EPOLLPRI;
 107                 goto unlock;
 108         }
 109         if (req->state != MEDIA_REQUEST_STATE_QUEUED) {
 110                 ret = EPOLLERR;
 111                 goto unlock;
 112         }
 113
 114 unlock:
 115         spin_unlock_irqrestore(&req->lock, flags);
 116         return ret;
 117 }
 118
 119 static long media_request_ioctl_queue(struct media_request *req)
 120 {
 121         struct media_device *mdev = req->mdev;
 122         enum media_request_state state;
 123         unsigned long flags;
 124         int ret;
 125
 126         dev_dbg(mdev->dev, "request: queue %s\n", req->debug_str);
 127
 128         /*
 129          * Ensure the request that is validated will be the one that gets queued
 130          * next by serialising the queueing process. This mutex is also used
 131          * to serialize with canceling a vb2 queue and with setting values such
 132          * as controls in a request.
 133          */
 134         mutex_lock(&mdev->req_queue_mutex);
 135
 136         media_request_get(req);
 137
 138         spin_lock_irqsave(&req->lock, flags);
 139         if (req->state == MEDIA_REQUEST_STATE_IDLE)
 140                 req->state = MEDIA_REQUEST_STATE_VALIDATING;
 141         state = req->state;
 142         spin_unlock_irqrestore(&req->lock, flags);
 143         if (state != MEDIA_REQUEST_STATE_VALIDATING) {
 144                 dev_dbg(mdev->dev,
 145                         "request: unable to queue %s, request in state %s\n",
 146                         req->debug_str, media_request_state_str(state));
 147                 media_request_put(req);
 148                 mutex_unlock(&mdev->req_queue_mutex);
 149                 return -EBUSY;
 150         }
 151
 152         ret = mdev->ops->req_validate(req);
 153
 154         /*
 155          * If the req_validate was successful, then we mark the state as QUEUED
 156          * and call req_queue. The reason we set the state first is that this
 157          * allows req_queue to unbind or complete the queued objects in case
 158          * they are immediately 'consumed'. State changes from QUEUED to another
 159          * state can only happen if either the driver changes the state or if
 160          * the user cancels the vb2 queue. The driver can only change the state
 161          * after each object is queued through the req_queue op (and note that
 162          * that op cannot fail), so setting the state to QUEUED up front is
 163          * safe.
 164          *
 165          * The other reason for changing the state is if the vb2 queue is
 166          * canceled, and that uses the req_queue_mutex which is still locked
 167          * while req_queue is called, so that's safe as well.
 168          */
 169         spin_lock_irqsave(&req->lock, flags);
 170         req->state = ret ? MEDIA_REQUEST_STATE_IDLE
 171                          : MEDIA_REQUEST_STATE_QUEUED;
 172         spin_unlock_irqrestore(&req->lock, flags);
 173
 174         if (!ret)
 175                 mdev->ops->req_queue(req);
 176
 177         mutex_unlock(&mdev->req_queue_mutex);
 178
 179         if (ret) {
 180                 dev_dbg(mdev->dev, "request: can't queue %s (%d)\n",
 181                         req->debug_str, ret);
 182                 media_request_put(req);
 183         }
 184
 185         return ret;
 186 }
 187
 188 static long media_request_ioctl_reinit(struct media_request *req)
 189 {
 190         struct media_device *mdev = req->mdev;
 191         unsigned long flags;
 192
 193         spin_lock_irqsave(&req->lock, flags);
 194         if (req->state != MEDIA_REQUEST_STATE_IDLE &&
 195             req->state != MEDIA_REQUEST_STATE_COMPLETE) {
 196                 dev_dbg(mdev->dev,
 197                         "request: %s not in idle or complete state, cannot reinit\n",
 198                         req->debug_str);
 199                 spin_unlock_irqrestore(&req->lock, flags);
 200                 return -EBUSY;
 201         }
 202         if (req->access_count) {
 203                 dev_dbg(mdev->dev,
 204                         "request: %s is being accessed, cannot reinit\n",
 205                         req->debug_str);
 206                 spin_unlock_irqrestore(&req->lock, flags);
 207                 return -EBUSY;
 208         }
 209         req->state = MEDIA_REQUEST_STATE_CLEANING;
 210         spin_unlock_irqrestore(&req->lock, flags);
 211
 212         media_request_clean(req);
 213
 214         spin_lock_irqsave(&req->lock, flags);
 215         req->state = MEDIA_REQUEST_STATE_IDLE;
 216         spin_unlock_irqrestore(&req->lock, flags);
 217
 218         return 0;
 219 }
 220
 221 static long media_request_ioctl(struct file *filp, unsigned int cmd,
 222                                 unsigned long arg)
 223 {
 224         struct media_request *req = filp->private_data;
 225
 226         switch (cmd) {
 227         case MEDIA_REQUEST_IOC_QUEUE:
 228                 return media_request_ioctl_queue(req);
 229         case MEDIA_REQUEST_IOC_REINIT:
 230                 return media_request_ioctl_reinit(req);
 231         default:
 232                 return -ENOIOCTLCMD;
 233         }
 234 }
 235
 236 static const struct file_operations request_fops = {
 237         .owner = THIS_MODULE,
 238         .poll = media_request_poll,
 239         .unlocked_ioctl = media_request_ioctl,
 240 #ifdef CONFIG_COMPAT
 241         .compat_ioctl = media_request_ioctl,
 242 #endif /* CONFIG_COMPAT */
 243         .release = media_request_close,
 244 };
 245
 246 struct media_request *
 247 media_request_get_by_fd(struct media_device *mdev, int request_fd)
 248 {
 249         struct file *filp;
 250         struct media_request *req;
 251
 252         if (!mdev || !mdev->ops ||
 253             !mdev->ops->req_validate || !mdev->ops->req_queue)
 254                 return ERR_PTR(-EACCES);
 255
 256         filp = fget(request_fd);
 257         if (!filp)
 258                 goto err_no_req_fd;
 259
 260         if (filp->f_op != &request_fops)
 261                 goto err_fput;
 262         req = filp->private_data;
 263         if (req->mdev != mdev)
 264                 goto err_fput;
 265
 266         /*
 267          * Note: as long as someone has an open filehandle of the request,
 268          * the request can never be released. The fget() above ensures that
 269          * even if userspace closes the request filehandle, the release()
 270          * fop won't be called, so the media_request_get() always succeeds
 271          * and there is no race condition where the request was released
 272          * before media_request_get() is called.
 273          */
 274         media_request_get(req);
 275         fput(filp);
 276
 277         return req;
 278
 279 err_fput:
 280         fput(filp);
 281
 282 err_no_req_fd:
 283         dev_dbg(mdev->dev, "cannot find request_fd %d\n", request_fd);
 284         return ERR_PTR(-EINVAL);
 285 }
 286 EXPORT_SYMBOL_GPL(media_request_get_by_fd);
 287
 288 int media_request_alloc(struct media_device *mdev, int *alloc_fd)
 289 {
 290         struct media_request *req;
 291         struct file *filp;
 292         int fd;
 293         int ret;
 294
 295         /* Either both are NULL or both are non-NULL */
 296         if (WARN_ON(!mdev->ops->req_alloc ^ !mdev->ops->req_free))
 297                 return -ENOMEM;
 298
 299         fd = get_unused_fd_flags(O_CLOEXEC);
 300         if (fd < 0)
 301                 return fd;
 302
 303         filp = anon_inode_getfile("request", &request_fops, NULL, O_CLOEXEC);
 304         if (IS_ERR(filp)) {
 305                 ret = PTR_ERR(filp);
 306                 goto err_put_fd;
 307         }
 308
 309         if (mdev->ops->req_alloc)
 310                 req = mdev->ops->req_alloc(mdev);
 311         else
 312                 req = kzalloc(sizeof(*req), GFP_KERNEL);
 313         if (!req) {
 314                 ret = -ENOMEM;
 315                 goto err_fput;
 316         }
 317
 318         filp->private_data = req;
 319         req->mdev = mdev;
 320         req->state = MEDIA_REQUEST_STATE_IDLE;
 321         req->num_incomplete_objects = 0;
 322         kref_init(&req->kref);
 323         INIT_LIST_HEAD(&req->objects);
 324         spin_lock_init(&req->lock);
 325         init_waitqueue_head(&req->poll_wait);
 326         req->updating_count = 0;
 327         req->access_count = 0;
 328
 329         *alloc_fd = fd;
 330
 331         snprintf(req->debug_str, sizeof(req->debug_str), "%u:%d",
 332                  atomic_inc_return(&mdev->request_id), fd);
 333         dev_dbg(mdev->dev, "request: allocated %s\n", req->debug_str);
 334
 335         fd_install(fd, filp);
 336
 337         return 0;
 338
 339 err_fput:
 340         fput(filp);
 341
 342 err_put_fd:
 343         put_unused_fd(fd);
 344
 345         return ret;
 346 }
 347
 348 static void media_request_object_release(struct kref *kref)
 349 {
 350         struct media_request_object *obj =
 351                 container_of(kref, struct media_request_object, kref);
 352         struct media_request *req = obj->req;
 353
 354         if (WARN_ON(req))
 355                 media_request_object_unbind(obj);
 356         obj->ops->release(obj);
 357 }
 358
 359 struct media_request_object *
 360 media_request_object_find(struct media_request *req,
 361                           const struct media_request_object_ops *ops,
 362                           void *priv)
 363 {
 364         struct media_request_object *obj;
 365         struct media_request_object *found = NULL;
 366         unsigned long flags;
 367
 368         if (WARN_ON(!ops || !priv))
 369                 return NULL;
 370
 371         spin_lock_irqsave(&req->lock, flags);
 372         list_for_each_entry(obj, &req->objects, list) {
 373                 if (obj->ops == ops && obj->priv == priv) {
 374                         media_request_object_get(obj);
 375                         found = obj;
 376                         break;
 377                 }
 378         }
 379         spin_unlock_irqrestore(&req->lock, flags);
 380         return found;
 381 }
 382 EXPORT_SYMBOL_GPL(media_request_object_find);
 383
 384 void media_request_object_put(struct media_request_object *obj)
 385 {
 386         kref_put(&obj->kref, media_request_object_release);
 387 }
 388 EXPORT_SYMBOL_GPL(media_request_object_put);
 389
 390 void media_request_object_init(struct media_request_object *obj)
 391 {
 392         obj->ops = NULL;
 393         obj->req = NULL;
 394         obj->priv = NULL;
 395         obj->completed = false;
 396         INIT_LIST_HEAD(&obj->list);
 397         kref_init(&obj->kref);
 398 }
 399 EXPORT_SYMBOL_GPL(media_request_object_init);
 400
 401 int media_request_object_bind(struct media_request *req,
 402                               const struct media_request_object_ops *ops,
 403                               void *priv, bool is_buffer,
 404                               struct media_request_object *obj)
 405 {
 406         unsigned long flags;
 407         int ret = -EBUSY;
 408
 409         if (WARN_ON(!ops->release))
 410                 return -EACCES;
 411
 412         spin_lock_irqsave(&req->lock, flags);
 413
 414         if (WARN_ON(req->state != MEDIA_REQUEST_STATE_UPDATING))
 415                 goto unlock;
 416
 417         obj->req = req;
 418         obj->ops = ops;
 419         obj->priv = priv;
 420
 421         if (is_buffer)
 422                 list_add_tail(&obj->list, &req->objects);
 423         else
 424                 list_add(&obj->list, &req->objects);
 425         req->num_incomplete_objects++;
 426         ret = 0;
 427
 428 unlock:
 429         spin_unlock_irqrestore(&req->lock, flags);
 430         return ret;
 431 }
 432 EXPORT_SYMBOL_GPL(media_request_object_bind);
 433
 434 void media_request_object_unbind(struct media_request_object *obj)
 435 {
 436         struct media_request *req = obj->req;
 437         unsigned long flags;
 438         bool completed = false;
 439
 440         if (WARN_ON(!req))
 441                 return;
 442
 443         spin_lock_irqsave(&req->lock, flags);
 444         list_del(&obj->list);
 445         obj->req = NULL;
 446
 447         if (req->state == MEDIA_REQUEST_STATE_COMPLETE)
 448                 goto unlock;
 449
 450         if (WARN_ON(req->state == MEDIA_REQUEST_STATE_VALIDATING))
 451                 goto unlock;
 452
 453         if (req->state == MEDIA_REQUEST_STATE_CLEANING) {
 454                 if (!obj->completed)
 455                         req->num_incomplete_objects--;
 456                 goto unlock;
 457         }
 458
 459         if (WARN_ON(!req->num_incomplete_objects))
 460                 goto unlock;
 461
 462         req->num_incomplete_objects--;
 463         if (req->state == MEDIA_REQUEST_STATE_QUEUED &&
 464             !req->num_incomplete_objects) {
 465                 req->state = MEDIA_REQUEST_STATE_COMPLETE;
 466                 completed = true;
 467                 wake_up_interruptible_all(&req->poll_wait);
 468         }
 469
 470 unlock:
 471         spin_unlock_irqrestore(&req->lock, flags);
 472         if (obj->ops->unbind)
 473                 obj->ops->unbind(obj);
 474         if (completed)
 475                 media_request_put(req);
 476 }
 477 EXPORT_SYMBOL_GPL(media_request_object_unbind);
 478
 479 void media_request_object_complete(struct media_request_object *obj)
 480 {
 481         struct media_request *req = obj->req;
 482         unsigned long flags;
 483         bool completed = false;
 484
 485         spin_lock_irqsave(&req->lock, flags);
 486         if (obj->completed)
 487                 goto unlock;
 488         obj->completed = true;
 489         if (WARN_ON(!req->num_incomplete_objects) ||
 490             WARN_ON(req->state != MEDIA_REQUEST_STATE_QUEUED))
 491                 goto unlock;
 492
 493         if (!--req->num_incomplete_objects) {
 494                 req->state = MEDIA_REQUEST_STATE_COMPLETE;
 495                 wake_up_interruptible_all(&req->poll_wait);
 496                 completed = true;
 497         }
 498 unlock:
 499         spin_unlock_irqrestore(&req->lock, flags);
 500         if (completed)
 501                 media_request_put(req);
 502 }
 503 EXPORT_SYMBOL_GPL(media_request_object_complete);