1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * The Virtio 9p transport driver 4 * 5 * This is a block based transport driver based on the lguest block driver 6 * code. 7 * 8 * Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation 9 * 10 * Based on virtio console driver 11 * Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation 12 */ 13 14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 15 16 #include <linux/in.h> 17 #include <linux/module.h> 18 #include <linux/net.h> 19 #include <linux/ipv6.h> 20 #include <linux/errno.h> 21 #include <linux/kernel.h> 22 #include <linux/un.h> 23 #include <linux/uaccess.h> 24 #include <linux/inet.h> 25 #include <linux/file.h> 26 #include <linux/highmem.h> 27 #include <linux/slab.h> 28 #include <net/9p/9p.h> 29 #include <linux/parser.h> 30 #include <net/9p/client.h> 31 #include <net/9p/transport.h> 32 #include <linux/scatterlist.h> 33 #include <linux/swap.h> 34 #include <linux/virtio.h> 35 #include <linux/virtio_9p.h> 36 #include "trans_common.h" 37 38 #define VIRTQUEUE_NUM 128 39 40 /* a single mutex to manage channel initialization and attachment */ 41 static DEFINE_MUTEX(virtio_9p_lock); 42 static DECLARE_WAIT_QUEUE_HEAD(vp_wq); 43 static atomic_t vp_pinned = ATOMIC_INIT(0); 44 45 /** 46 * struct virtio_chan - per-instance transport information 47 * @inuse: whether the channel is in use 48 * @lock: protects multiple elements within this structure 49 * @client: client instance 50 * @vdev: virtio dev associated with this channel 51 * @vq: virtio queue associated with this channel 52 * @ring_bufs_avail: flag to indicate there is some available in the ring buf 53 * @vc_wq: wait queue for waiting for thing to be added to ring buf 54 * @p9_max_pages: maximum number of pinned pages 55 * @sg: scatter gather list which is used to pack a request (protected?) 56 * @chan_list: linked list of channels 57 * 58 * We keep all per-channel information in a structure. 59 * This structure is allocated within the devices dev->mem space. 60 * A pointer to the structure will get put in the transport private. 61 * 62 */ 63 64 struct virtio_chan { 65 bool inuse; 66 67 spinlock_t lock; 68 69 struct p9_client *client; 70 struct virtio_device *vdev; 71 struct virtqueue *vq; 72 int ring_bufs_avail; 73 wait_queue_head_t *vc_wq; 74 /* This is global limit. Since we don't have a global structure, 75 * will be placing it in each channel. 76 */ 77 unsigned long p9_max_pages; 78 /* Scatterlist: can be too big for stack. */ 79 struct scatterlist sg[VIRTQUEUE_NUM]; 80 /** 81 * @tag: name to identify a mount null terminated 82 */ 83 char *tag; 84 85 struct list_head chan_list; 86 }; 87 88 static struct list_head virtio_chan_list; 89 90 /* How many bytes left in this page. */ 91 static unsigned int rest_of_page(void *data) 92 { 93 return PAGE_SIZE - offset_in_page(data); 94 } 95 96 /** 97 * p9_virtio_close - reclaim resources of a channel 98 * @client: client instance 99 * 100 * This reclaims a channel by freeing its resources and 101 * resetting its inuse flag. 102 * 103 */ 104 105 static void p9_virtio_close(struct p9_client *client) 106 { 107 struct virtio_chan *chan = client->trans; 108 109 mutex_lock(&virtio_9p_lock); 110 if (chan) 111 chan->inuse = false; 112 mutex_unlock(&virtio_9p_lock); 113 } 114 115 /** 116 * req_done - callback which signals activity from the server 117 * @vq: virtio queue activity was received on 118 * 119 * This notifies us that the server has triggered some activity 120 * on the virtio channel - most likely a response to request we 121 * sent. Figure out which requests now have responses and wake up 122 * those threads. 123 * 124 * Bugs: could do with some additional sanity checking, but appears to work. 125 * 126 */ 127 128 static void req_done(struct virtqueue *vq) 129 { 130 struct virtio_chan *chan = vq->vdev->priv; 131 unsigned int len; 132 struct p9_req_t *req; 133 bool need_wakeup = false; 134 unsigned long flags; 135 136 p9_debug(P9_DEBUG_TRANS, ": request done\n"); 137 138 spin_lock_irqsave(&chan->lock, flags); 139 while ((req = virtqueue_get_buf(chan->vq, &len)) != NULL) { 140 if (!chan->ring_bufs_avail) { 141 chan->ring_bufs_avail = 1; 142 need_wakeup = true; 143 } 144 145 if (len) { 146 req->rc.size = len; 147 p9_client_cb(chan->client, req, REQ_STATUS_RCVD); 148 } 149 } 150 spin_unlock_irqrestore(&chan->lock, flags); 151 /* Wakeup if anyone waiting for VirtIO ring space. */ 152 if (need_wakeup) 153 wake_up(chan->vc_wq); 154 } 155 156 /** 157 * pack_sg_list - pack a scatter gather list from a linear buffer 158 * @sg: scatter/gather list to pack into 159 * @start: which segment of the sg_list to start at 160 * @limit: maximum segment to pack data to 161 * @data: data to pack into scatter/gather list 162 * @count: amount of data to pack into the scatter/gather list 163 * 164 * sg_lists have multiple segments of various sizes. This will pack 165 * arbitrary data into an existing scatter gather list, segmenting the 166 * data as necessary within constraints. 167 * 168 */ 169 170 static int pack_sg_list(struct scatterlist *sg, int start, 171 int limit, char *data, int count) 172 { 173 int s; 174 int index = start; 175 176 while (count) { 177 s = rest_of_page(data); 178 if (s > count) 179 s = count; 180 BUG_ON(index >= limit); 181 /* Make sure we don't terminate early. */ 182 sg_unmark_end(&sg[index]); 183 sg_set_buf(&sg[index++], data, s); 184 count -= s; 185 data += s; 186 } 187 if (index-start) 188 sg_mark_end(&sg[index - 1]); 189 return index-start; 190 } 191 192 /* We don't currently allow canceling of virtio requests */ 193 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req) 194 { 195 return 1; 196 } 197 198 /* Reply won't come, so drop req ref */ 199 static int p9_virtio_cancelled(struct p9_client *client, struct p9_req_t *req) 200 { 201 p9_req_put(client, req); 202 return 0; 203 } 204 205 /** 206 * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer, 207 * this takes a list of pages. 208 * @sg: scatter/gather list to pack into 209 * @start: which segment of the sg_list to start at 210 * @limit: maximum number of pages in sg list. 211 * @pdata: a list of pages to add into sg. 212 * @nr_pages: number of pages to pack into the scatter/gather list 213 * @offs: amount of data in the beginning of first page _not_ to pack 214 * @count: amount of data to pack into the scatter/gather list 215 */ 216 static int 217 pack_sg_list_p(struct scatterlist *sg, int start, int limit, 218 struct page **pdata, int nr_pages, size_t offs, int count) 219 { 220 int i = 0, s; 221 int data_off = offs; 222 int index = start; 223 224 BUG_ON(nr_pages > (limit - start)); 225 /* 226 * if the first page doesn't start at 227 * page boundary find the offset 228 */ 229 while (nr_pages) { 230 s = PAGE_SIZE - data_off; 231 if (s > count) 232 s = count; 233 BUG_ON(index >= limit); 234 /* Make sure we don't terminate early. */ 235 sg_unmark_end(&sg[index]); 236 sg_set_page(&sg[index++], pdata[i++], s, data_off); 237 data_off = 0; 238 count -= s; 239 nr_pages--; 240 } 241 242 if (index-start) 243 sg_mark_end(&sg[index - 1]); 244 return index - start; 245 } 246 247 /** 248 * p9_virtio_request - issue a request 249 * @client: client instance issuing the request 250 * @req: request to be issued 251 * 252 */ 253 254 static int 255 p9_virtio_request(struct p9_client *client, struct p9_req_t *req) 256 { 257 int err; 258 int in, out, out_sgs, in_sgs; 259 unsigned long flags; 260 struct virtio_chan *chan = client->trans; 261 struct scatterlist *sgs[2]; 262 263 p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n"); 264 265 WRITE_ONCE(req->status, REQ_STATUS_SENT); 266 req_retry: 267 spin_lock_irqsave(&chan->lock, flags); 268 269 out_sgs = in_sgs = 0; 270 /* Handle out VirtIO ring buffers */ 271 out = pack_sg_list(chan->sg, 0, 272 VIRTQUEUE_NUM, req->tc.sdata, req->tc.size); 273 if (out) 274 sgs[out_sgs++] = chan->sg; 275 276 in = pack_sg_list(chan->sg, out, 277 VIRTQUEUE_NUM, req->rc.sdata, req->rc.capacity); 278 if (in) 279 sgs[out_sgs + in_sgs++] = chan->sg + out; 280 281 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req, 282 GFP_ATOMIC); 283 if (err < 0) { 284 if (err == -ENOSPC) { 285 chan->ring_bufs_avail = 0; 286 spin_unlock_irqrestore(&chan->lock, flags); 287 err = wait_event_killable(*chan->vc_wq, 288 chan->ring_bufs_avail); 289 if (err == -ERESTARTSYS) 290 return err; 291 292 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); 293 goto req_retry; 294 } else { 295 spin_unlock_irqrestore(&chan->lock, flags); 296 p9_debug(P9_DEBUG_TRANS, 297 "virtio rpc add_sgs returned failure\n"); 298 return -EIO; 299 } 300 } 301 virtqueue_kick(chan->vq); 302 spin_unlock_irqrestore(&chan->lock, flags); 303 304 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); 305 return 0; 306 } 307 308 static int p9_get_mapped_pages(struct virtio_chan *chan, 309 struct page ***pages, 310 struct iov_iter *data, 311 int count, 312 size_t *offs, 313 int *need_drop) 314 { 315 int nr_pages; 316 int err; 317 318 if (!iov_iter_count(data)) 319 return 0; 320 321 if (!iov_iter_is_kvec(data)) { 322 int n; 323 /* 324 * We allow only p9_max_pages pinned. We wait for the 325 * Other zc request to finish here 326 */ 327 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) { 328 err = wait_event_killable(vp_wq, 329 (atomic_read(&vp_pinned) < chan->p9_max_pages)); 330 if (err == -ERESTARTSYS) 331 return err; 332 } 333 n = iov_iter_get_pages_alloc2(data, pages, count, offs); 334 if (n < 0) 335 return n; 336 *need_drop = 1; 337 nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE); 338 atomic_add(nr_pages, &vp_pinned); 339 return n; 340 } else { 341 /* kernel buffer, no need to pin pages */ 342 int index; 343 size_t len; 344 void *p; 345 346 /* we'd already checked that it's non-empty */ 347 while (1) { 348 len = iov_iter_single_seg_count(data); 349 if (likely(len)) { 350 p = data->kvec->iov_base + data->iov_offset; 351 break; 352 } 353 iov_iter_advance(data, 0); 354 } 355 if (len > count) 356 len = count; 357 358 nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) - 359 (unsigned long)p / PAGE_SIZE; 360 361 *pages = kmalloc_array(nr_pages, sizeof(struct page *), 362 GFP_NOFS); 363 if (!*pages) 364 return -ENOMEM; 365 366 *need_drop = 0; 367 p -= (*offs = offset_in_page(p)); 368 for (index = 0; index < nr_pages; index++) { 369 if (is_vmalloc_addr(p)) 370 (*pages)[index] = vmalloc_to_page(p); 371 else 372 (*pages)[index] = kmap_to_page(p); 373 p += PAGE_SIZE; 374 } 375 iov_iter_advance(data, len); 376 return len; 377 } 378 } 379 380 static void handle_rerror(struct p9_req_t *req, int in_hdr_len, 381 size_t offs, struct page **pages) 382 { 383 unsigned size, n; 384 void *to = req->rc.sdata + in_hdr_len; 385 386 // Fits entirely into the static data? Nothing to do. 387 if (req->rc.size < in_hdr_len) 388 return; 389 390 // Really long error message? Tough, truncate the reply. Might get 391 // rejected (we can't be arsed to adjust the size encoded in header, 392 // or string size for that matter), but it wouldn't be anything valid 393 // anyway. 394 if (unlikely(req->rc.size > P9_ZC_HDR_SZ)) 395 req->rc.size = P9_ZC_HDR_SZ; 396 397 // data won't span more than two pages 398 size = req->rc.size - in_hdr_len; 399 n = PAGE_SIZE - offs; 400 if (size > n) { 401 memcpy_from_page(to, *pages++, offs, n); 402 offs = 0; 403 to += n; 404 size -= n; 405 } 406 memcpy_from_page(to, *pages, offs, size); 407 } 408 409 /** 410 * p9_virtio_zc_request - issue a zero copy request 411 * @client: client instance issuing the request 412 * @req: request to be issued 413 * @uidata: user buffer that should be used for zero copy read 414 * @uodata: user buffer that should be used for zero copy write 415 * @inlen: read buffer size 416 * @outlen: write buffer size 417 * @in_hdr_len: reader header size, This is the size of response protocol data 418 * 419 */ 420 static int 421 p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req, 422 struct iov_iter *uidata, struct iov_iter *uodata, 423 int inlen, int outlen, int in_hdr_len) 424 { 425 int in, out, err, out_sgs, in_sgs; 426 unsigned long flags; 427 int in_nr_pages = 0, out_nr_pages = 0; 428 struct page **in_pages = NULL, **out_pages = NULL; 429 struct virtio_chan *chan = client->trans; 430 struct scatterlist *sgs[4]; 431 size_t offs; 432 int need_drop = 0; 433 int kicked = 0; 434 435 p9_debug(P9_DEBUG_TRANS, "virtio request\n"); 436 437 if (uodata) { 438 __le32 sz; 439 int n = p9_get_mapped_pages(chan, &out_pages, uodata, 440 outlen, &offs, &need_drop); 441 if (n < 0) { 442 err = n; 443 goto err_out; 444 } 445 out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE); 446 if (n != outlen) { 447 __le32 v = cpu_to_le32(n); 448 memcpy(&req->tc.sdata[req->tc.size - 4], &v, 4); 449 outlen = n; 450 } 451 /* The size field of the message must include the length of the 452 * header and the length of the data. We didn't actually know 453 * the length of the data until this point so add it in now. 454 */ 455 sz = cpu_to_le32(req->tc.size + outlen); 456 memcpy(&req->tc.sdata[0], &sz, sizeof(sz)); 457 } else if (uidata) { 458 int n = p9_get_mapped_pages(chan, &in_pages, uidata, 459 inlen, &offs, &need_drop); 460 if (n < 0) { 461 err = n; 462 goto err_out; 463 } 464 in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE); 465 if (n != inlen) { 466 __le32 v = cpu_to_le32(n); 467 memcpy(&req->tc.sdata[req->tc.size - 4], &v, 4); 468 inlen = n; 469 } 470 } 471 WRITE_ONCE(req->status, REQ_STATUS_SENT); 472 req_retry_pinned: 473 spin_lock_irqsave(&chan->lock, flags); 474 475 out_sgs = in_sgs = 0; 476 477 /* out data */ 478 out = pack_sg_list(chan->sg, 0, 479 VIRTQUEUE_NUM, req->tc.sdata, req->tc.size); 480 481 if (out) 482 sgs[out_sgs++] = chan->sg; 483 484 if (out_pages) { 485 sgs[out_sgs++] = chan->sg + out; 486 out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM, 487 out_pages, out_nr_pages, offs, outlen); 488 } 489 490 /* 491 * Take care of in data 492 * For example TREAD have 11. 493 * 11 is the read/write header = PDU Header(7) + IO Size (4). 494 * Arrange in such a way that server places header in the 495 * allocated memory and payload onto the user buffer. 496 */ 497 in = pack_sg_list(chan->sg, out, 498 VIRTQUEUE_NUM, req->rc.sdata, in_hdr_len); 499 if (in) 500 sgs[out_sgs + in_sgs++] = chan->sg + out; 501 502 if (in_pages) { 503 sgs[out_sgs + in_sgs++] = chan->sg + out + in; 504 in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM, 505 in_pages, in_nr_pages, offs, inlen); 506 } 507 508 BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs)); 509 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req, 510 GFP_ATOMIC); 511 if (err < 0) { 512 if (err == -ENOSPC) { 513 chan->ring_bufs_avail = 0; 514 spin_unlock_irqrestore(&chan->lock, flags); 515 err = wait_event_killable(*chan->vc_wq, 516 chan->ring_bufs_avail); 517 if (err == -ERESTARTSYS) 518 goto err_out; 519 520 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); 521 goto req_retry_pinned; 522 } else { 523 spin_unlock_irqrestore(&chan->lock, flags); 524 p9_debug(P9_DEBUG_TRANS, 525 "virtio rpc add_sgs returned failure\n"); 526 err = -EIO; 527 goto err_out; 528 } 529 } 530 virtqueue_kick(chan->vq); 531 spin_unlock_irqrestore(&chan->lock, flags); 532 kicked = 1; 533 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); 534 err = wait_event_killable(req->wq, 535 READ_ONCE(req->status) >= REQ_STATUS_RCVD); 536 // RERROR needs reply (== error string) in static data 537 if (READ_ONCE(req->status) == REQ_STATUS_RCVD && 538 unlikely(req->rc.sdata[4] == P9_RERROR)) 539 handle_rerror(req, in_hdr_len, offs, in_pages); 540 541 /* 542 * Non kernel buffers are pinned, unpin them 543 */ 544 err_out: 545 if (need_drop) { 546 if (in_pages) { 547 p9_release_pages(in_pages, in_nr_pages); 548 atomic_sub(in_nr_pages, &vp_pinned); 549 } 550 if (out_pages) { 551 p9_release_pages(out_pages, out_nr_pages); 552 atomic_sub(out_nr_pages, &vp_pinned); 553 } 554 /* wakeup anybody waiting for slots to pin pages */ 555 wake_up(&vp_wq); 556 } 557 kvfree(in_pages); 558 kvfree(out_pages); 559 if (!kicked) { 560 /* reply won't come */ 561 p9_req_put(client, req); 562 } 563 return err; 564 } 565 566 static ssize_t p9_mount_tag_show(struct device *dev, 567 struct device_attribute *attr, char *buf) 568 { 569 struct virtio_chan *chan; 570 struct virtio_device *vdev; 571 int tag_len; 572 573 vdev = dev_to_virtio(dev); 574 chan = vdev->priv; 575 tag_len = strlen(chan->tag); 576 577 memcpy(buf, chan->tag, tag_len + 1); 578 579 return tag_len + 1; 580 } 581 582 static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL); 583 584 /** 585 * p9_virtio_probe - probe for existence of 9P virtio channels 586 * @vdev: virtio device to probe 587 * 588 * This probes for existing virtio channels. 589 * 590 */ 591 592 static int p9_virtio_probe(struct virtio_device *vdev) 593 { 594 __u16 tag_len; 595 char *tag; 596 int err; 597 struct virtio_chan *chan; 598 599 if (!vdev->config->get) { 600 dev_err(&vdev->dev, "%s failure: config access disabled\n", 601 __func__); 602 return -EINVAL; 603 } 604 605 chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL); 606 if (!chan) { 607 pr_err("Failed to allocate virtio 9P channel\n"); 608 err = -ENOMEM; 609 goto fail; 610 } 611 612 chan->vdev = vdev; 613 614 /* We expect one virtqueue, for requests. */ 615 chan->vq = virtio_find_single_vq(vdev, req_done, "requests"); 616 if (IS_ERR(chan->vq)) { 617 err = PTR_ERR(chan->vq); 618 goto out_free_chan; 619 } 620 chan->vq->vdev->priv = chan; 621 spin_lock_init(&chan->lock); 622 623 sg_init_table(chan->sg, VIRTQUEUE_NUM); 624 625 chan->inuse = false; 626 if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) { 627 virtio_cread(vdev, struct virtio_9p_config, tag_len, &tag_len); 628 } else { 629 err = -EINVAL; 630 goto out_free_vq; 631 } 632 tag = kzalloc(tag_len + 1, GFP_KERNEL); 633 if (!tag) { 634 err = -ENOMEM; 635 goto out_free_vq; 636 } 637 638 virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag), 639 tag, tag_len); 640 chan->tag = tag; 641 err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); 642 if (err) { 643 goto out_free_tag; 644 } 645 chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL); 646 if (!chan->vc_wq) { 647 err = -ENOMEM; 648 goto out_remove_file; 649 } 650 init_waitqueue_head(chan->vc_wq); 651 chan->ring_bufs_avail = 1; 652 /* Ceiling limit to avoid denial of service attacks */ 653 chan->p9_max_pages = nr_free_buffer_pages()/4; 654 655 virtio_device_ready(vdev); 656 657 mutex_lock(&virtio_9p_lock); 658 list_add_tail(&chan->chan_list, &virtio_chan_list); 659 mutex_unlock(&virtio_9p_lock); 660 661 /* Let udev rules use the new mount_tag attribute. */ 662 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE); 663 664 return 0; 665 666 out_remove_file: 667 sysfs_remove_file(&vdev->dev.kobj, &dev_attr_mount_tag.attr); 668 out_free_tag: 669 kfree(tag); 670 out_free_vq: 671 vdev->config->del_vqs(vdev); 672 out_free_chan: 673 kfree(chan); 674 fail: 675 return err; 676 } 677 678 679 /** 680 * p9_virtio_create - allocate a new virtio channel 681 * @client: client instance invoking this transport 682 * @devname: string identifying the channel to connect to (unused) 683 * @args: args passed from sys_mount() for per-transport options (unused) 684 * 685 * This sets up a transport channel for 9p communication. Right now 686 * we only match the first available channel, but eventually we could look up 687 * alternate channels by matching devname versus a virtio_config entry. 688 * We use a simple reference count mechanism to ensure that only a single 689 * mount has a channel open at a time. 690 * 691 */ 692 693 static int 694 p9_virtio_create(struct p9_client *client, const char *devname, char *args) 695 { 696 struct virtio_chan *chan; 697 int ret = -ENOENT; 698 int found = 0; 699 700 if (devname == NULL) 701 return -EINVAL; 702 703 mutex_lock(&virtio_9p_lock); 704 list_for_each_entry(chan, &virtio_chan_list, chan_list) { 705 if (!strcmp(devname, chan->tag)) { 706 if (!chan->inuse) { 707 chan->inuse = true; 708 found = 1; 709 break; 710 } 711 ret = -EBUSY; 712 } 713 } 714 mutex_unlock(&virtio_9p_lock); 715 716 if (!found) { 717 pr_err("no channels available for device %s\n", devname); 718 return ret; 719 } 720 721 client->trans = (void *)chan; 722 client->status = Connected; 723 chan->client = client; 724 725 return 0; 726 } 727 728 /** 729 * p9_virtio_remove - clean up resources associated with a virtio device 730 * @vdev: virtio device to remove 731 * 732 */ 733 734 static void p9_virtio_remove(struct virtio_device *vdev) 735 { 736 struct virtio_chan *chan = vdev->priv; 737 unsigned long warning_time; 738 739 mutex_lock(&virtio_9p_lock); 740 741 /* Remove self from list so we don't get new users. */ 742 list_del(&chan->chan_list); 743 warning_time = jiffies; 744 745 /* Wait for existing users to close. */ 746 while (chan->inuse) { 747 mutex_unlock(&virtio_9p_lock); 748 msleep(250); 749 if (time_after(jiffies, warning_time + 10 * HZ)) { 750 dev_emerg(&vdev->dev, 751 "p9_virtio_remove: waiting for device in use.\n"); 752 warning_time = jiffies; 753 } 754 mutex_lock(&virtio_9p_lock); 755 } 756 757 mutex_unlock(&virtio_9p_lock); 758 759 virtio_reset_device(vdev); 760 vdev->config->del_vqs(vdev); 761 762 sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); 763 kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE); 764 kfree(chan->tag); 765 kfree(chan->vc_wq); 766 kfree(chan); 767 768 } 769 770 static struct virtio_device_id id_table[] = { 771 { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID }, 772 { 0 }, 773 }; 774 775 static unsigned int features[] = { 776 VIRTIO_9P_MOUNT_TAG, 777 }; 778 779 /* The standard "struct lguest_driver": */ 780 static struct virtio_driver p9_virtio_drv = { 781 .feature_table = features, 782 .feature_table_size = ARRAY_SIZE(features), 783 .driver.name = KBUILD_MODNAME, 784 .driver.owner = THIS_MODULE, 785 .id_table = id_table, 786 .probe = p9_virtio_probe, 787 .remove = p9_virtio_remove, 788 }; 789 790 static struct p9_trans_module p9_virtio_trans = { 791 .name = "virtio", 792 .create = p9_virtio_create, 793 .close = p9_virtio_close, 794 .request = p9_virtio_request, 795 .zc_request = p9_virtio_zc_request, 796 .cancel = p9_virtio_cancel, 797 .cancelled = p9_virtio_cancelled, 798 /* 799 * We leave one entry for input and one entry for response 800 * headers. We also skip one more entry to accommodate, address 801 * that are not at page boundary, that can result in an extra 802 * page in zero copy. 803 */ 804 .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3), 805 .pooled_rbuffers = false, 806 .def = 1, 807 .owner = THIS_MODULE, 808 }; 809 810 /* The standard init function */ 811 static int __init p9_virtio_init(void) 812 { 813 int rc; 814 815 INIT_LIST_HEAD(&virtio_chan_list); 816 817 v9fs_register_trans(&p9_virtio_trans); 818 rc = register_virtio_driver(&p9_virtio_drv); 819 if (rc) 820 v9fs_unregister_trans(&p9_virtio_trans); 821 822 return rc; 823 } 824 825 static void __exit p9_virtio_cleanup(void) 826 { 827 unregister_virtio_driver(&p9_virtio_drv); 828 v9fs_unregister_trans(&p9_virtio_trans); 829 } 830 831 module_init(p9_virtio_init); 832 module_exit(p9_virtio_cleanup); 833 MODULE_ALIAS_9P("virtio"); 834 835 MODULE_DEVICE_TABLE(virtio, id_table); 836 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>"); 837 MODULE_DESCRIPTION("Virtio 9p Transport"); 838 MODULE_LICENSE("GPL"); 839