Version:  2.0.40 2.2.26 2.4.37 3.5 3.6 3.7 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

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 - ((unsigned long)data % PAGE_SIZE);
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         struct p9_fcall *rc;
147         unsigned int len;
148         struct p9_req_t *req;
149         unsigned long flags;
150 
151         p9_debug(P9_DEBUG_TRANS, ": request done\n");
152 
153         while (1) {
154                 spin_lock_irqsave(&chan->lock, flags);
155                 rc = virtqueue_get_buf(chan->vq, &len);
156                 if (rc == NULL) {
157                         spin_unlock_irqrestore(&chan->lock, flags);
158                         break;
159                 }
160                 chan->ring_bufs_avail = 1;
161                 spin_unlock_irqrestore(&chan->lock, flags);
162                 /* Wakeup if anyone waiting for VirtIO ring space. */
163                 wake_up(chan->vc_wq);
164                 p9_debug(P9_DEBUG_TRANS, ": rc %p\n", rc);
165                 p9_debug(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag);
166                 req = p9_tag_lookup(chan->client, rc->tag);
167                 p9_client_cb(chan->client, req, REQ_STATUS_RCVD);
168         }
169 }
170 
171 /**
172  * pack_sg_list - pack a scatter gather list from a linear buffer
173  * @sg: scatter/gather list to pack into
174  * @start: which segment of the sg_list to start at
175  * @limit: maximum segment to pack data to
176  * @data: data to pack into scatter/gather list
177  * @count: amount of data to pack into the scatter/gather list
178  *
179  * sg_lists have multiple segments of various sizes.  This will pack
180  * arbitrary data into an existing scatter gather list, segmenting the
181  * data as necessary within constraints.
182  *
183  */
184 
185 static int pack_sg_list(struct scatterlist *sg, int start,
186                         int limit, char *data, int count)
187 {
188         int s;
189         int index = start;
190 
191         while (count) {
192                 s = rest_of_page(data);
193                 if (s > count)
194                         s = count;
195                 BUG_ON(index > limit);
196                 /* Make sure we don't terminate early. */
197                 sg_unmark_end(&sg[index]);
198                 sg_set_buf(&sg[index++], data, s);
199                 count -= s;
200                 data += s;
201         }
202         if (index-start)
203                 sg_mark_end(&sg[index - 1]);
204         return index-start;
205 }
206 
207 /* We don't currently allow canceling of virtio requests */
208 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
209 {
210         return 1;
211 }
212 
213 /**
214  * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
215  * this takes a list of pages.
216  * @sg: scatter/gather list to pack into
217  * @start: which segment of the sg_list to start at
218  * @pdata: a list of pages to add into sg.
219  * @nr_pages: number of pages to pack into the scatter/gather list
220  * @offs: amount of data in the beginning of first page _not_ to pack
221  * @count: amount of data to pack into the scatter/gather list
222  */
223 static int
224 pack_sg_list_p(struct scatterlist *sg, int start, int limit,
225                struct page **pdata, int nr_pages, size_t offs, int count)
226 {
227         int i = 0, s;
228         int data_off = offs;
229         int index = start;
230 
231         BUG_ON(nr_pages > (limit - start));
232         /*
233          * if the first page doesn't start at
234          * page boundary find the offset
235          */
236         while (nr_pages) {
237                 s = PAGE_SIZE - data_off;
238                 if (s > count)
239                         s = count;
240                 /* Make sure we don't terminate early. */
241                 sg_unmark_end(&sg[index]);
242                 sg_set_page(&sg[index++], pdata[i++], s, data_off);
243                 data_off = 0;
244                 count -= s;
245                 nr_pages--;
246         }
247 
248         if (index-start)
249                 sg_mark_end(&sg[index - 1]);
250         return index - start;
251 }
252 
253 /**
254  * p9_virtio_request - issue a request
255  * @client: client instance issuing the request
256  * @req: request to be issued
257  *
258  */
259 
260 static int
261 p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
262 {
263         int err;
264         int in, out, out_sgs, in_sgs;
265         unsigned long flags;
266         struct virtio_chan *chan = client->trans;
267         struct scatterlist *sgs[2];
268 
269         p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n");
270 
271         req->status = REQ_STATUS_SENT;
272 req_retry:
273         spin_lock_irqsave(&chan->lock, flags);
274 
275         out_sgs = in_sgs = 0;
276         /* Handle out VirtIO ring buffers */
277         out = pack_sg_list(chan->sg, 0,
278                            VIRTQUEUE_NUM, req->tc->sdata, req->tc->size);
279         if (out)
280                 sgs[out_sgs++] = chan->sg;
281 
282         in = pack_sg_list(chan->sg, out,
283                           VIRTQUEUE_NUM, req->rc->sdata, req->rc->capacity);
284         if (in)
285                 sgs[out_sgs + in_sgs++] = chan->sg + out;
286 
287         err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req->tc,
288                                 GFP_ATOMIC);
289         if (err < 0) {
290                 if (err == -ENOSPC) {
291                         chan->ring_bufs_avail = 0;
292                         spin_unlock_irqrestore(&chan->lock, flags);
293                         err = wait_event_interruptible(*chan->vc_wq,
294                                                         chan->ring_bufs_avail);
295                         if (err  == -ERESTARTSYS)
296                                 return err;
297 
298                         p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
299                         goto req_retry;
300                 } else {
301                         spin_unlock_irqrestore(&chan->lock, flags);
302                         p9_debug(P9_DEBUG_TRANS,
303                                  "virtio rpc add_sgs returned failure\n");
304                         return -EIO;
305                 }
306         }
307         virtqueue_kick(chan->vq);
308         spin_unlock_irqrestore(&chan->lock, flags);
309 
310         p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
311         return 0;
312 }
313 
314 static int p9_get_mapped_pages(struct virtio_chan *chan,
315                                struct page ***pages,
316                                struct iov_iter *data,
317                                int count,
318                                size_t *offs,
319                                int *need_drop)
320 {
321         int nr_pages;
322         int err;
323 
324         if (!iov_iter_count(data))
325                 return 0;
326 
327         if (!(data->type & ITER_KVEC)) {
328                 int n;
329                 /*
330                  * We allow only p9_max_pages pinned. We wait for the
331                  * Other zc request to finish here
332                  */
333                 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
334                         err = wait_event_interruptible(vp_wq,
335                               (atomic_read(&vp_pinned) < chan->p9_max_pages));
336                         if (err == -ERESTARTSYS)
337                                 return err;
338                 }
339                 n = iov_iter_get_pages_alloc(data, pages, count, offs);
340                 if (n < 0)
341                         return n;
342                 *need_drop = 1;
343                 nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE);
344                 atomic_add(nr_pages, &vp_pinned);
345                 return n;
346         } else {
347                 /* kernel buffer, no need to pin pages */
348                 int index;
349                 size_t len;
350                 void *p;
351 
352                 /* we'd already checked that it's non-empty */
353                 while (1) {
354                         len = iov_iter_single_seg_count(data);
355                         if (likely(len)) {
356                                 p = data->kvec->iov_base + data->iov_offset;
357                                 break;
358                         }
359                         iov_iter_advance(data, 0);
360                 }
361                 if (len > count)
362                         len = count;
363 
364                 nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) -
365                            (unsigned long)p / PAGE_SIZE;
366 
367                 *pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_NOFS);
368                 if (!*pages)
369                         return -ENOMEM;
370 
371                 *need_drop = 0;
372                 p -= (*offs = (unsigned long)p % PAGE_SIZE);
373                 for (index = 0; index < nr_pages; index++) {
374                         if (is_vmalloc_addr(p))
375                                 (*pages)[index] = vmalloc_to_page(p);
376                         else
377                                 (*pages)[index] = kmap_to_page(p);
378                         p += PAGE_SIZE;
379                 }
380                 return len;
381         }
382 }
383 
384 /**
385  * p9_virtio_zc_request - issue a zero copy request
386  * @client: client instance issuing the request
387  * @req: request to be issued
388  * @uidata: user bffer that should be ued for zero copy read
389  * @uodata: user buffer that shoud be user for zero copy write
390  * @inlen: read buffer size
391  * @olen: write buffer size
392  * @hdrlen: reader header size, This is the size of response protocol data
393  *
394  */
395 static int
396 p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
397                      struct iov_iter *uidata, struct iov_iter *uodata,
398                      int inlen, int outlen, int in_hdr_len)
399 {
400         int in, out, err, out_sgs, in_sgs;
401         unsigned long flags;
402         int in_nr_pages = 0, out_nr_pages = 0;
403         struct page **in_pages = NULL, **out_pages = NULL;
404         struct virtio_chan *chan = client->trans;
405         struct scatterlist *sgs[4];
406         size_t offs;
407         int need_drop = 0;
408 
409         p9_debug(P9_DEBUG_TRANS, "virtio request\n");
410 
411         if (uodata) {
412                 int n = p9_get_mapped_pages(chan, &out_pages, uodata,
413                                             outlen, &offs, &need_drop);
414                 if (n < 0)
415                         return n;
416                 out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
417                 if (n != outlen) {
418                         __le32 v = cpu_to_le32(n);
419                         memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4);
420                         outlen = n;
421                 }
422         } else if (uidata) {
423                 int n = p9_get_mapped_pages(chan, &in_pages, uidata,
424                                             inlen, &offs, &need_drop);
425                 if (n < 0)
426                         return n;
427                 in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE);
428                 if (n != inlen) {
429                         __le32 v = cpu_to_le32(n);
430                         memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4);
431                         inlen = n;
432                 }
433         }
434         req->status = REQ_STATUS_SENT;
435 req_retry_pinned:
436         spin_lock_irqsave(&chan->lock, flags);
437 
438         out_sgs = in_sgs = 0;
439 
440         /* out data */
441         out = pack_sg_list(chan->sg, 0,
442                            VIRTQUEUE_NUM, req->tc->sdata, req->tc->size);
443 
444         if (out)
445                 sgs[out_sgs++] = chan->sg;
446 
447         if (out_pages) {
448                 sgs[out_sgs++] = chan->sg + out;
449                 out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
450                                       out_pages, out_nr_pages, offs, outlen);
451         }
452                 
453         /*
454          * Take care of in data
455          * For example TREAD have 11.
456          * 11 is the read/write header = PDU Header(7) + IO Size (4).
457          * Arrange in such a way that server places header in the
458          * alloced memory and payload onto the user buffer.
459          */
460         in = pack_sg_list(chan->sg, out,
461                           VIRTQUEUE_NUM, req->rc->sdata, in_hdr_len);
462         if (in)
463                 sgs[out_sgs + in_sgs++] = chan->sg + out;
464 
465         if (in_pages) {
466                 sgs[out_sgs + in_sgs++] = chan->sg + out + in;
467                 in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
468                                      in_pages, in_nr_pages, offs, inlen);
469         }
470 
471         BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs));
472         err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req->tc,
473                                 GFP_ATOMIC);
474         if (err < 0) {
475                 if (err == -ENOSPC) {
476                         chan->ring_bufs_avail = 0;
477                         spin_unlock_irqrestore(&chan->lock, flags);
478                         err = wait_event_interruptible(*chan->vc_wq,
479                                                        chan->ring_bufs_avail);
480                         if (err  == -ERESTARTSYS)
481                                 goto err_out;
482 
483                         p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n");
484                         goto req_retry_pinned;
485                 } else {
486                         spin_unlock_irqrestore(&chan->lock, flags);
487                         p9_debug(P9_DEBUG_TRANS,
488                                  "virtio rpc add_sgs returned failure\n");
489                         err = -EIO;
490                         goto err_out;
491                 }
492         }
493         virtqueue_kick(chan->vq);
494         spin_unlock_irqrestore(&chan->lock, flags);
495         p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
496         err = wait_event_interruptible(*req->wq,
497                                        req->status >= REQ_STATUS_RCVD);
498         /*
499          * Non kernel buffers are pinned, unpin them
500          */
501 err_out:
502         if (need_drop) {
503                 if (in_pages) {
504                         p9_release_pages(in_pages, in_nr_pages);
505                         atomic_sub(in_nr_pages, &vp_pinned);
506                 }
507                 if (out_pages) {
508                         p9_release_pages(out_pages, out_nr_pages);
509                         atomic_sub(out_nr_pages, &vp_pinned);
510                 }
511                 /* wakeup anybody waiting for slots to pin pages */
512                 wake_up(&vp_wq);
513         }
514         kfree(in_pages);
515         kfree(out_pages);
516         return err;
517 }
518 
519 static ssize_t p9_mount_tag_show(struct device *dev,
520                                 struct device_attribute *attr, char *buf)
521 {
522         struct virtio_chan *chan;
523         struct virtio_device *vdev;
524 
525         vdev = dev_to_virtio(dev);
526         chan = vdev->priv;
527 
528         memcpy(buf, chan->tag, chan->tag_len);
529         buf[chan->tag_len] = 0;
530 
531         return chan->tag_len + 1;
532 }
533 
534 static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
535 
536 /**
537  * p9_virtio_probe - probe for existence of 9P virtio channels
538  * @vdev: virtio device to probe
539  *
540  * This probes for existing virtio channels.
541  *
542  */
543 
544 static int p9_virtio_probe(struct virtio_device *vdev)
545 {
546         __u16 tag_len;
547         char *tag;
548         int err;
549         struct virtio_chan *chan;
550 
551         if (!vdev->config->get) {
552                 dev_err(&vdev->dev, "%s failure: config access disabled\n",
553                         __func__);
554                 return -EINVAL;
555         }
556 
557         chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL);
558         if (!chan) {
559                 pr_err("Failed to allocate virtio 9P channel\n");
560                 err = -ENOMEM;
561                 goto fail;
562         }
563 
564         chan->vdev = vdev;
565 
566         /* We expect one virtqueue, for requests. */
567         chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
568         if (IS_ERR(chan->vq)) {
569                 err = PTR_ERR(chan->vq);
570                 goto out_free_vq;
571         }
572         chan->vq->vdev->priv = chan;
573         spin_lock_init(&chan->lock);
574 
575         sg_init_table(chan->sg, VIRTQUEUE_NUM);
576 
577         chan->inuse = false;
578         if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) {
579                 virtio_cread(vdev, struct virtio_9p_config, tag_len, &tag_len);
580         } else {
581                 err = -EINVAL;
582                 goto out_free_vq;
583         }
584         tag = kmalloc(tag_len, GFP_KERNEL);
585         if (!tag) {
586                 err = -ENOMEM;
587                 goto out_free_vq;
588         }
589 
590         virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag),
591                            tag, tag_len);
592         chan->tag = tag;
593         chan->tag_len = tag_len;
594         err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
595         if (err) {
596                 goto out_free_tag;
597         }
598         chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL);
599         if (!chan->vc_wq) {
600                 err = -ENOMEM;
601                 goto out_free_tag;
602         }
603         init_waitqueue_head(chan->vc_wq);
604         chan->ring_bufs_avail = 1;
605         /* Ceiling limit to avoid denial of service attacks */
606         chan->p9_max_pages = nr_free_buffer_pages()/4;
607 
608         virtio_device_ready(vdev);
609 
610         mutex_lock(&virtio_9p_lock);
611         list_add_tail(&chan->chan_list, &virtio_chan_list);
612         mutex_unlock(&virtio_9p_lock);
613 
614         /* Let udev rules use the new mount_tag attribute. */
615         kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
616 
617         return 0;
618 
619 out_free_tag:
620         kfree(tag);
621 out_free_vq:
622         vdev->config->del_vqs(vdev);
623         kfree(chan);
624 fail:
625         return err;
626 }
627 
628 
629 /**
630  * p9_virtio_create - allocate a new virtio channel
631  * @client: client instance invoking this transport
632  * @devname: string identifying the channel to connect to (unused)
633  * @args: args passed from sys_mount() for per-transport options (unused)
634  *
635  * This sets up a transport channel for 9p communication.  Right now
636  * we only match the first available channel, but eventually we couldlook up
637  * alternate channels by matching devname versus a virtio_config entry.
638  * We use a simple reference count mechanism to ensure that only a single
639  * mount has a channel open at a time.
640  *
641  */
642 
643 static int
644 p9_virtio_create(struct p9_client *client, const char *devname, char *args)
645 {
646         struct virtio_chan *chan;
647         int ret = -ENOENT;
648         int found = 0;
649 
650         mutex_lock(&virtio_9p_lock);
651         list_for_each_entry(chan, &virtio_chan_list, chan_list) {
652                 if (!strncmp(devname, chan->tag, chan->tag_len) &&
653                     strlen(devname) == chan->tag_len) {
654                         if (!chan->inuse) {
655                                 chan->inuse = true;
656                                 found = 1;
657                                 break;
658                         }
659                         ret = -EBUSY;
660                 }
661         }
662         mutex_unlock(&virtio_9p_lock);
663 
664         if (!found) {
665                 pr_err("no channels available\n");
666                 return ret;
667         }
668 
669         client->trans = (void *)chan;
670         client->status = Connected;
671         chan->client = client;
672 
673         return 0;
674 }
675 
676 /**
677  * p9_virtio_remove - clean up resources associated with a virtio device
678  * @vdev: virtio device to remove
679  *
680  */
681 
682 static void p9_virtio_remove(struct virtio_device *vdev)
683 {
684         struct virtio_chan *chan = vdev->priv;
685         unsigned long warning_time;
686 
687         mutex_lock(&virtio_9p_lock);
688 
689         /* Remove self from list so we don't get new users. */
690         list_del(&chan->chan_list);
691         warning_time = jiffies;
692 
693         /* Wait for existing users to close. */
694         while (chan->inuse) {
695                 mutex_unlock(&virtio_9p_lock);
696                 msleep(250);
697                 if (time_after(jiffies, warning_time + 10 * HZ)) {
698                         dev_emerg(&vdev->dev,
699                                   "p9_virtio_remove: waiting for device in use.\n");
700                         warning_time = jiffies;
701                 }
702                 mutex_lock(&virtio_9p_lock);
703         }
704 
705         mutex_unlock(&virtio_9p_lock);
706 
707         vdev->config->del_vqs(vdev);
708 
709         sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
710         kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);
711         kfree(chan->tag);
712         kfree(chan->vc_wq);
713         kfree(chan);
714 
715 }
716 
717 static struct virtio_device_id id_table[] = {
718         { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
719         { 0 },
720 };
721 
722 static unsigned int features[] = {
723         VIRTIO_9P_MOUNT_TAG,
724 };
725 
726 /* The standard "struct lguest_driver": */
727 static struct virtio_driver p9_virtio_drv = {
728         .feature_table  = features,
729         .feature_table_size = ARRAY_SIZE(features),
730         .driver.name    = KBUILD_MODNAME,
731         .driver.owner   = THIS_MODULE,
732         .id_table       = id_table,
733         .probe          = p9_virtio_probe,
734         .remove         = p9_virtio_remove,
735 };
736 
737 static struct p9_trans_module p9_virtio_trans = {
738         .name = "virtio",
739         .create = p9_virtio_create,
740         .close = p9_virtio_close,
741         .request = p9_virtio_request,
742         .zc_request = p9_virtio_zc_request,
743         .cancel = p9_virtio_cancel,
744         /*
745          * We leave one entry for input and one entry for response
746          * headers. We also skip one more entry to accomodate, address
747          * that are not at page boundary, that can result in an extra
748          * page in zero copy.
749          */
750         .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3),
751         .def = 1,
752         .owner = THIS_MODULE,
753 };
754 
755 /* The standard init function */
756 static int __init p9_virtio_init(void)
757 {
758         INIT_LIST_HEAD(&virtio_chan_list);
759 
760         v9fs_register_trans(&p9_virtio_trans);
761         return register_virtio_driver(&p9_virtio_drv);
762 }
763 
764 static void __exit p9_virtio_cleanup(void)
765 {
766         unregister_virtio_driver(&p9_virtio_drv);
767         v9fs_unregister_trans(&p9_virtio_trans);
768 }
769 
770 module_init(p9_virtio_init);
771 module_exit(p9_virtio_cleanup);
772 
773 MODULE_DEVICE_TABLE(virtio, id_table);
774 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
775 MODULE_DESCRIPTION("Virtio 9p Transport");
776 MODULE_LICENSE("GPL");
777 

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