Version:  2.0.40 2.2.26 2.4.37 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5

Linux/net/9p/trans_virtio.c

  1 /*
  2  * The Virtio 9p transport driver
  3  *
  4  * This is a block based transport driver based on the lguest block driver
  5  * code.
  6  *
  7  *  Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
  8  *
  9  *  Based on virtio console driver
 10  *  Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
 11  *
 12  *  This program is free software; you can redistribute it and/or modify
 13  *  it under the terms of the GNU General Public License version 2
 14  *  as published by the Free Software Foundation.
 15  *
 16  *  This program is distributed in the hope that it will be useful,
 17  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 18  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 19  *  GNU General Public License for more details.
 20  *
 21  *  You should have received a copy of the GNU General Public License
 22  *  along with this program; if not, write to:
 23  *  Free Software Foundation
 24  *  51 Franklin Street, Fifth Floor
 25  *  Boston, MA  02111-1301  USA
 26  *
 27  */
 28 
 29 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 30 
 31 #include <linux/in.h>
 32 #include <linux/module.h>
 33 #include <linux/net.h>
 34 #include <linux/ipv6.h>
 35 #include <linux/errno.h>
 36 #include <linux/kernel.h>
 37 #include <linux/un.h>
 38 #include <linux/uaccess.h>
 39 #include <linux/inet.h>
 40 #include <linux/idr.h>
 41 #include <linux/file.h>
 42 #include <linux/highmem.h>
 43 #include <linux/slab.h>
 44 #include <net/9p/9p.h>
 45 #include <linux/parser.h>
 46 #include <net/9p/client.h>
 47 #include <net/9p/transport.h>
 48 #include <linux/scatterlist.h>
 49 #include <linux/swap.h>
 50 #include <linux/virtio.h>
 51 #include <linux/virtio_9p.h>
 52 #include "trans_common.h"
 53 
 54 #define VIRTQUEUE_NUM   128
 55 
 56 /* a single mutex to manage channel initialization and attachment */
 57 static DEFINE_MUTEX(virtio_9p_lock);
 58 static DECLARE_WAIT_QUEUE_HEAD(vp_wq);
 59 static atomic_t vp_pinned = ATOMIC_INIT(0);
 60 
 61 /**
 62  * struct virtio_chan - per-instance transport information
 63  * @initialized: whether the channel is initialized
 64  * @inuse: whether the channel is in use
 65  * @lock: protects multiple elements within this structure
 66  * @client: client instance
 67  * @vdev: virtio dev associated with this channel
 68  * @vq: virtio queue associated with this channel
 69  * @sg: scatter gather list which is used to pack a request (protected?)
 70  *
 71  * We keep all per-channel information in a structure.
 72  * This structure is allocated within the devices dev->mem space.
 73  * A pointer to the structure will get put in the transport private.
 74  *
 75  */
 76 
 77 struct virtio_chan {
 78         bool inuse;
 79 
 80         spinlock_t lock;
 81 
 82         struct p9_client *client;
 83         struct virtio_device *vdev;
 84         struct virtqueue *vq;
 85         int ring_bufs_avail;
 86         wait_queue_head_t *vc_wq;
 87         /* This is global limit. Since we don't have a global structure,
 88          * will be placing it in each channel.
 89          */
 90         unsigned long p9_max_pages;
 91         /* Scatterlist: can be too big for stack. */
 92         struct scatterlist sg[VIRTQUEUE_NUM];
 93 
 94         int tag_len;
 95         /*
 96          * tag name to identify a mount Non-null terminated
 97          */
 98         char *tag;
 99 
100         struct list_head chan_list;
101 };
102 
103 static struct list_head virtio_chan_list;
104 
105 /* How many bytes left in this page. */
106 static unsigned int rest_of_page(void *data)
107 {
108         return PAGE_SIZE - offset_in_page(data);
109 }
110 
111 /**
112  * p9_virtio_close - reclaim resources of a channel
113  * @client: client instance
114  *
115  * This reclaims a channel by freeing its resources and
116  * reseting its inuse flag.
117  *
118  */
119 
120 static void p9_virtio_close(struct p9_client *client)
121 {
122         struct virtio_chan *chan = client->trans;
123 
124         mutex_lock(&virtio_9p_lock);
125         if (chan)
126                 chan->inuse = false;
127         mutex_unlock(&virtio_9p_lock);
128 }
129 
130 /**
131  * req_done - callback which signals activity from the server
132  * @vq: virtio queue activity was received on
133  *
134  * This notifies us that the server has triggered some activity
135  * on the virtio channel - most likely a response to request we
136  * sent.  Figure out which requests now have responses and wake up
137  * those threads.
138  *
139  * Bugs: could do with some additional sanity checking, but appears to work.
140  *
141  */
142 
143 static void req_done(struct virtqueue *vq)
144 {
145         struct virtio_chan *chan = vq->vdev->priv;
146         unsigned int len;
147         struct p9_req_t *req;
148         unsigned long flags;
149 
150         p9_debug(P9_DEBUG_TRANS, ": request done\n");
151 
152         while (1) {
153                 spin_lock_irqsave(&chan->lock, flags);
154                 req = virtqueue_get_buf(chan->vq, &len);
155                 if (req == NULL) {
156                         spin_unlock_irqrestore(&chan->lock, flags);
157                         break;
158                 }
159                 chan->ring_bufs_avail = 1;
160                 spin_unlock_irqrestore(&chan->lock, flags);
161                 /* Wakeup if anyone waiting for VirtIO ring space. */
162                 wake_up(chan->vc_wq);
163                 p9_client_cb(chan->client, req, REQ_STATUS_RCVD);
164         }
165 }
166 
167 /**
168  * pack_sg_list - pack a scatter gather list from a linear buffer
169  * @sg: scatter/gather list to pack into
170  * @start: which segment of the sg_list to start at
171  * @limit: maximum segment to pack data to
172  * @data: data to pack into scatter/gather list
173  * @count: amount of data to pack into the scatter/gather list
174  *
175  * sg_lists have multiple segments of various sizes.  This will pack
176  * arbitrary data into an existing scatter gather list, segmenting the
177  * data as necessary within constraints.
178  *
179  */
180 
181 static int pack_sg_list(struct scatterlist *sg, int start,
182                         int limit, char *data, int count)
183 {
184         int s;
185         int index = start;
186 
187         while (count) {
188                 s = rest_of_page(data);
189                 if (s > count)
190                         s = count;
191                 BUG_ON(index > limit);
192                 /* Make sure we don't terminate early. */
193                 sg_unmark_end(&sg[index]);
194                 sg_set_buf(&sg[index++], data, s);
195                 count -= s;
196                 data += s;
197         }
198         if (index-start)
199                 sg_mark_end(&sg[index - 1]);
200         return index-start;
201 }
202 
203 /* We don't currently allow canceling of virtio requests */
204 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
205 {
206         return 1;
207 }
208 
209 /**
210  * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
211  * this takes a list of pages.
212  * @sg: scatter/gather list to pack into
213  * @start: which segment of the sg_list to start at
214  * @pdata: a list of pages to add into sg.
215  * @nr_pages: number of pages to pack into the scatter/gather list
216  * @offs: amount of data in the beginning of first page _not_ to pack
217  * @count: amount of data to pack into the scatter/gather list
218  */
219 static int
220 pack_sg_list_p(struct scatterlist *sg, int start, int limit,
221                struct page **pdata, int nr_pages, size_t offs, int count)
222 {
223         int i = 0, s;
224         int data_off = offs;
225         int index = start;
226 
227         BUG_ON(nr_pages > (limit - start));
228         /*
229          * if the first page doesn't start at
230          * page boundary find the offset
231          */
232         while (nr_pages) {
233                 s = PAGE_SIZE - data_off;
234                 if (s > count)
235                         s = count;
236                 /* Make sure we don't terminate early. */
237                 sg_unmark_end(&sg[index]);
238                 sg_set_page(&sg[index++], pdata[i++], s, data_off);
239                 data_off = 0;
240                 count -= s;
241                 nr_pages--;
242         }
243 
244         if (index-start)
245                 sg_mark_end(&sg[index - 1]);
246         return index - start;
247 }
248 
249 /**
250  * p9_virtio_request - issue a request
251  * @client: client instance issuing the request
252  * @req: request to be issued
253  *
254  */
255 
256 static int
257 p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
258 {
259         int err;
260         int in, out, out_sgs, in_sgs;
261         unsigned long flags;
262         struct virtio_chan *chan = client->trans;
263         struct scatterlist *sgs[2];
264 
265         p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n");
266 
267         req->status = REQ_STATUS_SENT;
268 req_retry:
269         spin_lock_irqsave(&chan->lock, flags);
270 
271         out_sgs = in_sgs = 0;
272         /* Handle out VirtIO ring buffers */
273         out = pack_sg_list(chan->sg, 0,
274                            VIRTQUEUE_NUM, req->tc->sdata, req->tc->size);
275         if (out)
276                 sgs[out_sgs++] = chan->sg;
277 
278         in = pack_sg_list(chan->sg, out,
279                           VIRTQUEUE_NUM, req->rc->sdata, req->rc->capacity);
280         if (in)
281                 sgs[out_sgs + in_sgs++] = chan->sg + out;
282 
283         err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req,
284                                 GFP_ATOMIC);
285         if (err < 0) {
286                 if (err == -ENOSPC) {
287                         chan->ring_bufs_avail = 0;
288                         spin_unlock_irqrestore(&chan->lock, flags);
289                         err = wait_event_interruptible(*chan->vc_wq,
290                                                         chan->ring_bufs_avail);
291                         if (err  == -ERESTARTSYS)
292                                 return err;
293 
294                         p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
295                         goto req_retry;
296                 } else {
297                         spin_unlock_irqrestore(&chan->lock, flags);
298                         p9_debug(P9_DEBUG_TRANS,
299                                  "virtio rpc add_sgs returned failure\n");
300                         return -EIO;
301                 }
302         }
303         virtqueue_kick(chan->vq);
304         spin_unlock_irqrestore(&chan->lock, flags);
305 
306         p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
307         return 0;
308 }
309 
310 static int p9_get_mapped_pages(struct virtio_chan *chan,
311                                struct page ***pages,
312                                struct iov_iter *data,
313                                int count,
314                                size_t *offs,
315                                int *need_drop)
316 {
317         int nr_pages;
318         int err;
319 
320         if (!iov_iter_count(data))
321                 return 0;
322 
323         if (!(data->type & ITER_KVEC)) {
324                 int n;
325                 /*
326                  * We allow only p9_max_pages pinned. We wait for the
327                  * Other zc request to finish here
328                  */
329                 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
330                         err = wait_event_interruptible(vp_wq,
331                               (atomic_read(&vp_pinned) < chan->p9_max_pages));
332                         if (err == -ERESTARTSYS)
333                                 return err;
334                 }
335                 n = iov_iter_get_pages_alloc(data, pages, count, offs);
336                 if (n < 0)
337                         return n;
338                 *need_drop = 1;
339                 nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE);
340                 atomic_add(nr_pages, &vp_pinned);
341                 return n;
342         } else {
343                 /* kernel buffer, no need to pin pages */
344                 int index;
345                 size_t len;
346                 void *p;
347 
348                 /* we'd already checked that it's non-empty */
349                 while (1) {
350                         len = iov_iter_single_seg_count(data);
351                         if (likely(len)) {
352                                 p = data->kvec->iov_base + data->iov_offset;
353                                 break;
354                         }
355                         iov_iter_advance(data, 0);
356                 }
357                 if (len > count)
358                         len = count;
359 
360                 nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) -
361                            (unsigned long)p / PAGE_SIZE;
362 
363                 *pages = kmalloc(sizeof(struct page *) * nr_pages, 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                 return len;
377         }
378 }
379 
380 /**
381  * p9_virtio_zc_request - issue a zero copy request
382  * @client: client instance issuing the request
383  * @req: request to be issued
384  * @uidata: user bffer that should be ued for zero copy read
385  * @uodata: user buffer that shoud be user for zero copy write
386  * @inlen: read buffer size
387  * @olen: write buffer size
388  * @hdrlen: reader header size, This is the size of response protocol data
389  *
390  */
391 static int
392 p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
393                      struct iov_iter *uidata, struct iov_iter *uodata,
394                      int inlen, int outlen, int in_hdr_len)
395 {
396         int in, out, err, out_sgs, in_sgs;
397         unsigned long flags;
398         int in_nr_pages = 0, out_nr_pages = 0;
399         struct page **in_pages = NULL, **out_pages = NULL;
400         struct virtio_chan *chan = client->trans;
401         struct scatterlist *sgs[4];
402         size_t offs;
403         int need_drop = 0;
404 
405         p9_debug(P9_DEBUG_TRANS, "virtio request\n");
406 
407         if (uodata) {
408                 int n = p9_get_mapped_pages(chan, &out_pages, uodata,
409                                             outlen, &offs, &need_drop);
410                 if (n < 0)
411                         return n;
412                 out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
413                 if (n != outlen) {
414                         __le32 v = cpu_to_le32(n);
415                         memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4);
416                         outlen = n;
417                 }
418         } else if (uidata) {
419                 int n = p9_get_mapped_pages(chan, &in_pages, uidata,
420                                             inlen, &offs, &need_drop);
421                 if (n < 0)
422                         return n;
423                 in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
424                 if (n != inlen) {
425                         __le32 v = cpu_to_le32(n);
426                         memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4);
427                         inlen = n;
428                 }
429         }
430         req->status = REQ_STATUS_SENT;
431 req_retry_pinned:
432         spin_lock_irqsave(&chan->lock, flags);
433 
434         out_sgs = in_sgs = 0;
435 
436         /* out data */
437         out = pack_sg_list(chan->sg, 0,
438                            VIRTQUEUE_NUM, req->tc->sdata, req->tc->size);
439 
440         if (out)
441                 sgs[out_sgs++] = chan->sg;
442 
443         if (out_pages) {
444                 sgs[out_sgs++] = chan->sg + out;
445                 out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
446                                       out_pages, out_nr_pages, offs, outlen);
447         }
448                 
449         /*
450          * Take care of in data
451          * For example TREAD have 11.
452          * 11 is the read/write header = PDU Header(7) + IO Size (4).
453          * Arrange in such a way that server places header in the
454          * alloced memory and payload onto the user buffer.
455          */
456         in = pack_sg_list(chan->sg, out,
457                           VIRTQUEUE_NUM, req->rc->sdata, in_hdr_len);
458         if (in)
459                 sgs[out_sgs + in_sgs++] = chan->sg + out;
460 
461         if (in_pages) {
462                 sgs[out_sgs + in_sgs++] = chan->sg + out + in;
463                 in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
464                                      in_pages, in_nr_pages, offs, inlen);
465         }
466 
467         BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs));
468         err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req,
469                                 GFP_ATOMIC);
470         if (err < 0) {
471                 if (err == -ENOSPC) {
472                         chan->ring_bufs_avail = 0;
473                         spin_unlock_irqrestore(&chan->lock, flags);
474                         err = wait_event_interruptible(*chan->vc_wq,
475                                                        chan->ring_bufs_avail);
476                         if (err  == -ERESTARTSYS)
477                                 goto err_out;
478 
479                         p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
480                         goto req_retry_pinned;
481                 } else {
482                         spin_unlock_irqrestore(&chan->lock, flags);
483                         p9_debug(P9_DEBUG_TRANS,
484                                  "virtio rpc add_sgs returned failure\n");
485                         err = -EIO;
486                         goto err_out;
487                 }
488         }
489         virtqueue_kick(chan->vq);
490         spin_unlock_irqrestore(&chan->lock, flags);
491         p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
492         err = wait_event_interruptible(*req->wq,
493                                        req->status >= REQ_STATUS_RCVD);
494         /*
495          * Non kernel buffers are pinned, unpin them
496          */
497 err_out:
498         if (need_drop) {
499                 if (in_pages) {
500                         p9_release_pages(in_pages, in_nr_pages);
501                         atomic_sub(in_nr_pages, &vp_pinned);
502                 }
503                 if (out_pages) {
504                         p9_release_pages(out_pages, out_nr_pages);
505                         atomic_sub(out_nr_pages, &vp_pinned);
506                 }
507                 /* wakeup anybody waiting for slots to pin pages */
508                 wake_up(&vp_wq);
509         }
510         kfree(in_pages);
511         kfree(out_pages);
512         return err;
513 }
514 
515 static ssize_t p9_mount_tag_show(struct device *dev,
516                                 struct device_attribute *attr, char *buf)
517 {
518         struct virtio_chan *chan;
519         struct virtio_device *vdev;
520 
521         vdev = dev_to_virtio(dev);
522         chan = vdev->priv;
523 
524         memcpy(buf, chan->tag, chan->tag_len);
525         buf[chan->tag_len] = 0;
526 
527         return chan->tag_len + 1;
528 }
529 
530 static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
531 
532 /**
533  * p9_virtio_probe - probe for existence of 9P virtio channels
534  * @vdev: virtio device to probe
535  *
536  * This probes for existing virtio channels.
537  *
538  */
539 
540 static int p9_virtio_probe(struct virtio_device *vdev)
541 {
542         __u16 tag_len;
543         char *tag;
544         int err;
545         struct virtio_chan *chan;
546 
547         if (!vdev->config->get) {
548                 dev_err(&vdev->dev, "%s failure: config access disabled\n",
549                         __func__);
550                 return -EINVAL;
551         }
552 
553         chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL);
554         if (!chan) {
555                 pr_err("Failed to allocate virtio 9P channel\n");
556                 err = -ENOMEM;
557                 goto fail;
558         }
559 
560         chan->vdev = vdev;
561 
562         /* We expect one virtqueue, for requests. */
563         chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
564         if (IS_ERR(chan->vq)) {
565                 err = PTR_ERR(chan->vq);
566                 goto out_free_vq;
567         }
568         chan->vq->vdev->priv = chan;
569         spin_lock_init(&chan->lock);
570 
571         sg_init_table(chan->sg, VIRTQUEUE_NUM);
572 
573         chan->inuse = false;
574         if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) {
575                 virtio_cread(vdev, struct virtio_9p_config, tag_len, &tag_len);
576         } else {
577                 err = -EINVAL;
578                 goto out_free_vq;
579         }
580         tag = kmalloc(tag_len, GFP_KERNEL);
581         if (!tag) {
582                 err = -ENOMEM;
583                 goto out_free_vq;
584         }
585 
586         virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag),
587                            tag, tag_len);
588         chan->tag = tag;
589         chan->tag_len = tag_len;
590         err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
591         if (err) {
592                 goto out_free_tag;
593         }
594         chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL);
595         if (!chan->vc_wq) {
596                 err = -ENOMEM;
597                 goto out_free_tag;
598         }
599         init_waitqueue_head(chan->vc_wq);
600         chan->ring_bufs_avail = 1;
601         /* Ceiling limit to avoid denial of service attacks */
602         chan->p9_max_pages = nr_free_buffer_pages()/4;
603 
604         virtio_device_ready(vdev);
605 
606         mutex_lock(&virtio_9p_lock);
607         list_add_tail(&chan->chan_list, &virtio_chan_list);
608         mutex_unlock(&virtio_9p_lock);
609 
610         /* Let udev rules use the new mount_tag attribute. */
611         kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
612 
613         return 0;
614 
615 out_free_tag:
616         kfree(tag);
617 out_free_vq:
618         vdev->config->del_vqs(vdev);
619         kfree(chan);
620 fail:
621         return err;
622 }
623 
624 
625 /**
626  * p9_virtio_create - allocate a new virtio channel
627  * @client: client instance invoking this transport
628  * @devname: string identifying the channel to connect to (unused)
629  * @args: args passed from sys_mount() for per-transport options (unused)
630  *
631  * This sets up a transport channel for 9p communication.  Right now
632  * we only match the first available channel, but eventually we couldlook up
633  * alternate channels by matching devname versus a virtio_config entry.
634  * We use a simple reference count mechanism to ensure that only a single
635  * mount has a channel open at a time.
636  *
637  */
638 
639 static int
640 p9_virtio_create(struct p9_client *client, const char *devname, char *args)
641 {
642         struct virtio_chan *chan;
643         int ret = -ENOENT;
644         int found = 0;
645 
646         mutex_lock(&virtio_9p_lock);
647         list_for_each_entry(chan, &virtio_chan_list, chan_list) {
648                 if (!strncmp(devname, chan->tag, chan->tag_len) &&
649                     strlen(devname) == chan->tag_len) {
650                         if (!chan->inuse) {
651                                 chan->inuse = true;
652                                 found = 1;
653                                 break;
654                         }
655                         ret = -EBUSY;
656                 }
657         }
658         mutex_unlock(&virtio_9p_lock);
659 
660         if (!found) {
661                 pr_err("no channels available for device %s\n", devname);
662                 return ret;
663         }
664 
665         client->trans = (void *)chan;
666         client->status = Connected;
667         chan->client = client;
668 
669         return 0;
670 }
671 
672 /**
673  * p9_virtio_remove - clean up resources associated with a virtio device
674  * @vdev: virtio device to remove
675  *
676  */
677 
678 static void p9_virtio_remove(struct virtio_device *vdev)
679 {
680         struct virtio_chan *chan = vdev->priv;
681         unsigned long warning_time;
682 
683         mutex_lock(&virtio_9p_lock);
684 
685         /* Remove self from list so we don't get new users. */
686         list_del(&chan->chan_list);
687         warning_time = jiffies;
688 
689         /* Wait for existing users to close. */
690         while (chan->inuse) {
691                 mutex_unlock(&virtio_9p_lock);
692                 msleep(250);
693                 if (time_after(jiffies, warning_time + 10 * HZ)) {
694                         dev_emerg(&vdev->dev,
695                                   "p9_virtio_remove: waiting for device in use.\n");
696                         warning_time = jiffies;
697                 }
698                 mutex_lock(&virtio_9p_lock);
699         }
700 
701         mutex_unlock(&virtio_9p_lock);
702 
703         vdev->config->reset(vdev);
704         vdev->config->del_vqs(vdev);
705 
706         sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
707         kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
708         kfree(chan->tag);
709         kfree(chan->vc_wq);
710         kfree(chan);
711 
712 }
713 
714 static struct virtio_device_id id_table[] = {
715         { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
716         { 0 },
717 };
718 
719 static unsigned int features[] = {
720         VIRTIO_9P_MOUNT_TAG,
721 };
722 
723 /* The standard "struct lguest_driver": */
724 static struct virtio_driver p9_virtio_drv = {
725         .feature_table  = features,
726         .feature_table_size = ARRAY_SIZE(features),
727         .driver.name    = KBUILD_MODNAME,
728         .driver.owner   = THIS_MODULE,
729         .id_table       = id_table,
730         .probe          = p9_virtio_probe,
731         .remove         = p9_virtio_remove,
732 };
733 
734 static struct p9_trans_module p9_virtio_trans = {
735         .name = "virtio",
736         .create = p9_virtio_create,
737         .close = p9_virtio_close,
738         .request = p9_virtio_request,
739         .zc_request = p9_virtio_zc_request,
740         .cancel = p9_virtio_cancel,
741         /*
742          * We leave one entry for input and one entry for response
743          * headers. We also skip one more entry to accomodate, address
744          * that are not at page boundary, that can result in an extra
745          * page in zero copy.
746          */
747         .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3),
748         .def = 1,
749         .owner = THIS_MODULE,
750 };
751 
752 /* The standard init function */
753 static int __init p9_virtio_init(void)
754 {
755         INIT_LIST_HEAD(&virtio_chan_list);
756 
757         v9fs_register_trans(&p9_virtio_trans);
758         return register_virtio_driver(&p9_virtio_drv);
759 }
760 
761 static void __exit p9_virtio_cleanup(void)
762 {
763         unregister_virtio_driver(&p9_virtio_drv);
764         v9fs_unregister_trans(&p9_virtio_trans);
765 }
766 
767 module_init(p9_virtio_init);
768 module_exit(p9_virtio_cleanup);
769 
770 MODULE_DEVICE_TABLE(virtio, id_table);
771 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
772 MODULE_DESCRIPTION("Virtio 9p Transport");
773 MODULE_LICENSE("GPL");
774 

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