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/idr.h> 26 #include <linux/file.h> 27 #include <linux/highmem.h> 28 #include <linux/slab.h> 29 #include <net/9p/9p.h> 30 #include <linux/parser.h> 31 #include <net/9p/client.h> 32 #include <net/9p/transport.h> 33 #include <linux/scatterlist.h> 34 #include <linux/swap.h> 35 #include <linux/virtio.h> 36 #include <linux/virtio_9p.h> 37 #include "trans_common.h" 38 39 #define VIRTQUEUE_NUM 128 40 41 /* a single mutex to manage channel initialization and attachment */ 42 static DEFINE_MUTEX(virtio_9p_lock); 43 static DECLARE_WAIT_QUEUE_HEAD(vp_wq); 44 static atomic_t vp_pinned = ATOMIC_INIT(0); 45 46 /** 47 * struct virtio_chan - per-instance transport information 48 * @inuse: whether the channel is in use 49 * @lock: protects multiple elements within this structure 50 * @client: client instance 51 * @vdev: virtio dev associated with this channel 52 * @vq: virtio queue associated with this channel 53 * @ring_bufs_avail: flag to indicate there is some available in the ring buf 54 * @vc_wq: wait queue for waiting for thing to be added to ring buf 55 * @p9_max_pages: maximum number of pinned pages 56 * @sg: scatter gather list which is used to pack a request (protected?) 57 * @chan_list: linked list of channels 58 * 59 * We keep all per-channel information in a structure. 60 * This structure is allocated within the devices dev->mem space. 61 * A pointer to the structure will get put in the transport private. 62 * 63 */ 64 65 struct virtio_chan { 66 bool inuse; 67 68 spinlock_t lock; 69 70 struct p9_client *client; 71 struct virtio_device *vdev; 72 struct virtqueue *vq; 73 int ring_bufs_avail; 74 wait_queue_head_t *vc_wq; 75 /* This is global limit. Since we don't have a global structure, 76 * will be placing it in each channel. 77 */ 78 unsigned long p9_max_pages; 79 /* Scatterlist: can be too big for stack. */ 80 struct scatterlist sg[VIRTQUEUE_NUM]; 81 /** 82 * @tag: name to identify a mount null terminated 83 */ 84 char *tag; 85 86 struct list_head chan_list; 87 }; 88 89 static struct list_head virtio_chan_list; 90 91 /* How many bytes left in this page. */ 92 static unsigned int rest_of_page(void *data) 93 { 94 return PAGE_SIZE - offset_in_page(data); 95 } 96 97 /** 98 * p9_virtio_close - reclaim resources of a channel 99 * @client: client instance 100 * 101 * This reclaims a channel by freeing its resources and 102 * resetting its inuse flag. 103 * 104 */ 105 106 static void p9_virtio_close(struct p9_client *client) 107 { 108 struct virtio_chan *chan = client->trans; 109 110 mutex_lock(&virtio_9p_lock); 111 if (chan) 112 chan->inuse = false; 113 mutex_unlock(&virtio_9p_lock); 114 } 115 116 /** 117 * req_done - callback which signals activity from the server 118 * @vq: virtio queue activity was received on 119 * 120 * This notifies us that the server has triggered some activity 121 * on the virtio channel - most likely a response to request we 122 * sent. Figure out which requests now have responses and wake up 123 * those threads. 124 * 125 * Bugs: could do with some additional sanity checking, but appears to work. 126 * 127 */ 128 129 static void req_done(struct virtqueue *vq) 130 { 131 struct virtio_chan *chan = vq->vdev->priv; 132 unsigned int len; 133 struct p9_req_t *req; 134 bool need_wakeup = false; 135 unsigned long flags; 136 137 p9_debug(P9_DEBUG_TRANS, ": request done\n"); 138 139 spin_lock_irqsave(&chan->lock, flags); 140 while ((req = virtqueue_get_buf(chan->vq, &len)) != NULL) { 141 if (!chan->ring_bufs_avail) { 142 chan->ring_bufs_avail = 1; 143 need_wakeup = true; 144 } 145 146 if (len) { 147 req->rc.size = len; 148 p9_client_cb(chan->client, req, REQ_STATUS_RCVD); 149 } 150 } 151 spin_unlock_irqrestore(&chan->lock, flags); 152 /* Wakeup if anyone waiting for VirtIO ring space. */ 153 if (need_wakeup) 154 wake_up(chan->vc_wq); 155 } 156 157 /** 158 * pack_sg_list - pack a scatter gather list from a linear buffer 159 * @sg: scatter/gather list to pack into 160 * @start: which segment of the sg_list to start at 161 * @limit: maximum segment to pack data to 162 * @data: data to pack into scatter/gather list 163 * @count: amount of data to pack into the scatter/gather list 164 * 165 * sg_lists have multiple segments of various sizes. This will pack 166 * arbitrary data into an existing scatter gather list, segmenting the 167 * data as necessary within constraints. 168 * 169 */ 170 171 static int pack_sg_list(struct scatterlist *sg, int start, 172 int limit, char *data, int count) 173 { 174 int s; 175 int index = start; 176 177 while (count) { 178 s = rest_of_page(data); 179 if (s > count) 180 s = count; 181 BUG_ON(index >= limit); 182 /* Make sure we don't terminate early. */ 183 sg_unmark_end(&sg[index]); 184 sg_set_buf(&sg[index++], data, s); 185 count -= s; 186 data += s; 187 } 188 if (index-start) 189 sg_mark_end(&sg[index - 1]); 190 return index-start; 191 } 192 193 /* We don't currently allow canceling of virtio requests */ 194 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req) 195 { 196 return 1; 197 } 198 199 /* Reply won't come, so drop req ref */ 200 static int p9_virtio_cancelled(struct p9_client *client, struct p9_req_t *req) 201 { 202 p9_req_put(client, req); 203 return 0; 204 } 205 206 /** 207 * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer, 208 * this takes a list of pages. 209 * @sg: scatter/gather list to pack into 210 * @start: which segment of the sg_list to start at 211 * @limit: maximum number of pages in sg list. 212 * @pdata: a list of pages to add into sg. 213 * @nr_pages: number of pages to pack into the scatter/gather list 214 * @offs: amount of data in the beginning of first page _not_ to pack 215 * @count: amount of data to pack into the scatter/gather list 216 */ 217 static int 218 pack_sg_list_p(struct scatterlist *sg, int start, int limit, 219 struct page **pdata, int nr_pages, size_t offs, int count) 220 { 221 int i = 0, s; 222 int data_off = offs; 223 int index = start; 224 225 BUG_ON(nr_pages > (limit - start)); 226 /* 227 * if the first page doesn't start at 228 * page boundary find the offset 229 */ 230 while (nr_pages) { 231 s = PAGE_SIZE - data_off; 232 if (s > count) 233 s = count; 234 BUG_ON(index >= limit); 235 /* Make sure we don't terminate early. */ 236 sg_unmark_end(&sg[index]); 237 sg_set_page(&sg[index++], pdata[i++], s, data_off); 238 data_off = 0; 239 count -= s; 240 nr_pages--; 241 } 242 243 if (index-start) 244 sg_mark_end(&sg[index - 1]); 245 return index - start; 246 } 247 248 /** 249 * p9_virtio_request - issue a request 250 * @client: client instance issuing the request 251 * @req: request to be issued 252 * 253 */ 254 255 static int 256 p9_virtio_request(struct p9_client *client, struct p9_req_t *req) 257 { 258 int err; 259 int in, out, out_sgs, in_sgs; 260 unsigned long flags; 261 struct virtio_chan *chan = client->trans; 262 struct scatterlist *sgs[2]; 263 264 p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n"); 265 266 req->status = REQ_STATUS_SENT; 267 req_retry: 268 spin_lock_irqsave(&chan->lock, flags); 269 270 out_sgs = in_sgs = 0; 271 /* Handle out VirtIO ring buffers */ 272 out = pack_sg_list(chan->sg, 0, 273 VIRTQUEUE_NUM, req->tc.sdata, req->tc.size); 274 if (out) 275 sgs[out_sgs++] = chan->sg; 276 277 in = pack_sg_list(chan->sg, out, 278 VIRTQUEUE_NUM, req->rc.sdata, req->rc.capacity); 279 if (in) 280 sgs[out_sgs + in_sgs++] = chan->sg + out; 281 282 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req, 283 GFP_ATOMIC); 284 if (err < 0) { 285 if (err == -ENOSPC) { 286 chan->ring_bufs_avail = 0; 287 spin_unlock_irqrestore(&chan->lock, flags); 288 err = wait_event_killable(*chan->vc_wq, 289 chan->ring_bufs_avail); 290 if (err == -ERESTARTSYS) 291 return err; 292 293 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); 294 goto req_retry; 295 } else { 296 spin_unlock_irqrestore(&chan->lock, flags); 297 p9_debug(P9_DEBUG_TRANS, 298 "virtio rpc add_sgs returned failure\n"); 299 return -EIO; 300 } 301 } 302 virtqueue_kick(chan->vq); 303 spin_unlock_irqrestore(&chan->lock, flags); 304 305 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); 306 return 0; 307 } 308 309 static int p9_get_mapped_pages(struct virtio_chan *chan, 310 struct page ***pages, 311 struct iov_iter *data, 312 int count, 313 size_t *offs, 314 int *need_drop) 315 { 316 int nr_pages; 317 int err; 318 319 if (!iov_iter_count(data)) 320 return 0; 321 322 if (!iov_iter_is_kvec(data)) { 323 int n; 324 /* 325 * We allow only p9_max_pages pinned. We wait for the 326 * Other zc request to finish here 327 */ 328 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) { 329 err = wait_event_killable(vp_wq, 330 (atomic_read(&vp_pinned) < chan->p9_max_pages)); 331 if (err == -ERESTARTSYS) 332 return err; 333 } 334 n = iov_iter_get_pages_alloc2(data, pages, count, offs); 335 if (n < 0) 336 return n; 337 *need_drop = 1; 338 nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE); 339 atomic_add(nr_pages, &vp_pinned); 340 return n; 341 } else { 342 /* kernel buffer, no need to pin pages */ 343 int index; 344 size_t len; 345 void *p; 346 347 /* we'd already checked that it's non-empty */ 348 while (1) { 349 len = iov_iter_single_seg_count(data); 350 if (likely(len)) { 351 p = data->kvec->iov_base + data->iov_offset; 352 break; 353 } 354 iov_iter_advance(data, 0); 355 } 356 if (len > count) 357 len = count; 358 359 nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) - 360 (unsigned long)p / PAGE_SIZE; 361 362 *pages = kmalloc_array(nr_pages, sizeof(struct page *), 363 GFP_NOFS); 364 if (!*pages) 365 return -ENOMEM; 366 367 *need_drop = 0; 368 p -= (*offs = offset_in_page(p)); 369 for (index = 0; index < nr_pages; index++) { 370 if (is_vmalloc_addr(p)) 371 (*pages)[index] = vmalloc_to_page(p); 372 else 373 (*pages)[index] = kmap_to_page(p); 374 p += PAGE_SIZE; 375 } 376 iov_iter_advance(data, len); 377 return len; 378 } 379 } 380 381 static void handle_rerror(struct p9_req_t *req, int in_hdr_len, 382 size_t offs, struct page **pages) 383 { 384 unsigned size, n; 385 void *to = req->rc.sdata + in_hdr_len; 386 387 // Fits entirely into the static data? Nothing to do. 388 if (req->rc.size < in_hdr_len) 389 return; 390 391 // Really long error message? Tough, truncate the reply. Might get 392 // rejected (we can't be arsed to adjust the size encoded in header, 393 // or string size for that matter), but it wouldn't be anything valid 394 // anyway. 395 if (unlikely(req->rc.size > P9_ZC_HDR_SZ)) 396 req->rc.size = P9_ZC_HDR_SZ; 397 398 // data won't span more than two pages 399 size = req->rc.size - in_hdr_len; 400 n = PAGE_SIZE - offs; 401 if (size > n) { 402 memcpy_from_page(to, *pages++, offs, n); 403 offs = 0; 404 to += n; 405 size -= n; 406 } 407 memcpy_from_page(to, *pages, offs, size); 408 } 409 410 /** 411 * p9_virtio_zc_request - issue a zero copy request 412 * @client: client instance issuing the request 413 * @req: request to be issued 414 * @uidata: user buffer that should be used for zero copy read 415 * @uodata: user buffer that should be used for zero copy write 416 * @inlen: read buffer size 417 * @outlen: write buffer size 418 * @in_hdr_len: reader header size, This is the size of response protocol data 419 * 420 */ 421 static int 422 p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req, 423 struct iov_iter *uidata, struct iov_iter *uodata, 424 int inlen, int outlen, int in_hdr_len) 425 { 426 int in, out, err, out_sgs, in_sgs; 427 unsigned long flags; 428 int in_nr_pages = 0, out_nr_pages = 0; 429 struct page **in_pages = NULL, **out_pages = NULL; 430 struct virtio_chan *chan = client->trans; 431 struct scatterlist *sgs[4]; 432 size_t offs; 433 int need_drop = 0; 434 int kicked = 0; 435 436 p9_debug(P9_DEBUG_TRANS, "virtio request\n"); 437 438 if (uodata) { 439 __le32 sz; 440 int n = p9_get_mapped_pages(chan, &out_pages, uodata, 441 outlen, &offs, &need_drop); 442 if (n < 0) { 443 err = n; 444 goto err_out; 445 } 446 out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE); 447 if (n != outlen) { 448 __le32 v = cpu_to_le32(n); 449 memcpy(&req->tc.sdata[req->tc.size - 4], &v, 4); 450 outlen = n; 451 } 452 /* The size field of the message must include the length of the 453 * header and the length of the data. We didn't actually know 454 * the length of the data until this point so add it in now. 455 */ 456 sz = cpu_to_le32(req->tc.size + outlen); 457 memcpy(&req->tc.sdata[0], &sz, sizeof(sz)); 458 } else if (uidata) { 459 int n = p9_get_mapped_pages(chan, &in_pages, uidata, 460 inlen, &offs, &need_drop); 461 if (n < 0) { 462 err = n; 463 goto err_out; 464 } 465 in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE); 466 if (n != inlen) { 467 __le32 v = cpu_to_le32(n); 468 memcpy(&req->tc.sdata[req->tc.size - 4], &v, 4); 469 inlen = n; 470 } 471 } 472 req->status = REQ_STATUS_SENT; 473 req_retry_pinned: 474 spin_lock_irqsave(&chan->lock, flags); 475 476 out_sgs = in_sgs = 0; 477 478 /* out data */ 479 out = pack_sg_list(chan->sg, 0, 480 VIRTQUEUE_NUM, req->tc.sdata, req->tc.size); 481 482 if (out) 483 sgs[out_sgs++] = chan->sg; 484 485 if (out_pages) { 486 sgs[out_sgs++] = chan->sg + out; 487 out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM, 488 out_pages, out_nr_pages, offs, outlen); 489 } 490 491 /* 492 * Take care of in data 493 * For example TREAD have 11. 494 * 11 is the read/write header = PDU Header(7) + IO Size (4). 495 * Arrange in such a way that server places header in the 496 * allocated memory and payload onto the user buffer. 497 */ 498 in = pack_sg_list(chan->sg, out, 499 VIRTQUEUE_NUM, req->rc.sdata, in_hdr_len); 500 if (in) 501 sgs[out_sgs + in_sgs++] = chan->sg + out; 502 503 if (in_pages) { 504 sgs[out_sgs + in_sgs++] = chan->sg + out + in; 505 in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM, 506 in_pages, in_nr_pages, offs, inlen); 507 } 508 509 BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs)); 510 err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req, 511 GFP_ATOMIC); 512 if (err < 0) { 513 if (err == -ENOSPC) { 514 chan->ring_bufs_avail = 0; 515 spin_unlock_irqrestore(&chan->lock, flags); 516 err = wait_event_killable(*chan->vc_wq, 517 chan->ring_bufs_avail); 518 if (err == -ERESTARTSYS) 519 goto err_out; 520 521 p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); 522 goto req_retry_pinned; 523 } else { 524 spin_unlock_irqrestore(&chan->lock, flags); 525 p9_debug(P9_DEBUG_TRANS, 526 "virtio rpc add_sgs returned failure\n"); 527 err = -EIO; 528 goto err_out; 529 } 530 } 531 virtqueue_kick(chan->vq); 532 spin_unlock_irqrestore(&chan->lock, flags); 533 kicked = 1; 534 p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); 535 err = wait_event_killable(req->wq, req->status >= REQ_STATUS_RCVD); 536 // RERROR needs reply (== error string) in static data 537 if (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