cregit-Linux how code gets into the kernel

Release 4.8 net/9p/trans_virtio.c

Directory: net/9p
/*
 * The Virtio 9p transport driver
 *
 * This is a block based transport driver based on the lguest block driver
 * code.
 *
 *  Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
 *
 *  Based on virtio console driver
 *  Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA
 *
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/in.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/ipv6.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/un.h>
#include <linux/uaccess.h>
#include <linux/inet.h>
#include <linux/idr.h>
#include <linux/file.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <net/9p/9p.h>
#include <linux/parser.h>
#include <net/9p/client.h>
#include <net/9p/transport.h>
#include <linux/scatterlist.h>
#include <linux/swap.h>
#include <linux/virtio.h>
#include <linux/virtio_9p.h>
#include "trans_common.h"


#define VIRTQUEUE_NUM	128

/* a single mutex to manage channel initialization and attachment */
static DEFINE_MUTEX(virtio_9p_lock);
static DECLARE_WAIT_QUEUE_HEAD(vp_wq);

static atomic_t vp_pinned = ATOMIC_INIT(0);

/**
 * struct virtio_chan - per-instance transport information
 * @initialized: whether the channel is initialized
 * @inuse: whether the channel is in use
 * @lock: protects multiple elements within this structure
 * @client: client instance
 * @vdev: virtio dev associated with this channel
 * @vq: virtio queue associated with this channel
 * @sg: scatter gather list which is used to pack a request (protected?)
 *
 * We keep all per-channel information in a structure.
 * This structure is allocated within the devices dev->mem space.
 * A pointer to the structure will get put in the transport private.
 *
 */


struct virtio_chan {
	
bool inuse;

	
spinlock_t lock;

	
struct p9_client *client;
	
struct virtio_device *vdev;
	
struct virtqueue *vq;
	
int ring_bufs_avail;
	
wait_queue_head_t *vc_wq;
	/* This is global limit. Since we don't have a global structure,
         * will be placing it in each channel.
         */
	
unsigned long p9_max_pages;
	/* Scatterlist: can be too big for stack. */
	
struct scatterlist sg[VIRTQUEUE_NUM];

	
int tag_len;
	/*
         * tag name to identify a mount Non-null terminated
         */
	
char *tag;

	
struct list_head chan_list;
};


static struct list_head virtio_chan_list;

/* How many bytes left in this page. */

static unsigned int rest_of_page(void *data) { return PAGE_SIZE - offset_in_page(data); }

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eric van hensbergeneric van hensbergen1684.21%150.00%
al viroal viro315.79%150.00%
Total19100.00%2100.00%

/** * p9_virtio_close - reclaim resources of a channel * @client: client instance * * This reclaims a channel by freeing its resources and * reseting its inuse flag. * */
static void p9_virtio_close(struct p9_client *client) { struct virtio_chan *chan = client->trans; mutex_lock(&virtio_9p_lock); if (chan) chan->inuse = false; mutex_unlock(&virtio_9p_lock); }

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eric van hensbergeneric van hensbergen3685.71%360.00%
aneesh kumaraneesh kumar49.52%120.00%
josef sipekjosef sipek24.76%120.00%
Total42100.00%5100.00%

/** * req_done - callback which signals activity from the server * @vq: virtio queue activity was received on * * This notifies us that the server has triggered some activity * on the virtio channel - most likely a response to request we * sent. Figure out which requests now have responses and wake up * those threads. * * Bugs: could do with some additional sanity checking, but appears to work. * */
static void req_done(struct virtqueue *vq) { struct virtio_chan *chan = vq->vdev->priv; unsigned int len; struct p9_req_t *req; unsigned long flags; p9_debug(P9_DEBUG_TRANS, ": request done\n"); while (1) { spin_lock_irqsave(&chan->lock, flags); req = virtqueue_get_buf(chan->vq, &len); if (req == NULL) { spin_unlock_irqrestore(&chan->lock, flags); break; } chan->ring_bufs_avail = 1; spin_unlock_irqrestore(&chan->lock, flags); /* Wakeup if anyone waiting for VirtIO ring space. */ wake_up(chan->vc_wq); p9_client_cb(chan->client, req, REQ_STATUS_RCVD); } }

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venkateswararao jujjurivenkateswararao jujjuri6350.81%436.36%
eric van hensbergeneric van hensbergen5544.35%327.27%
al viroal viro21.61%19.09%
dominique martinetdominique martinet21.61%19.09%
joe perchesjoe perches10.81%19.09%
michael s. tsirkinmichael s. tsirkin10.81%19.09%
Total124100.00%11100.00%

/** * pack_sg_list - pack a scatter gather list from a linear buffer * @sg: scatter/gather list to pack into * @start: which segment of the sg_list to start at * @limit: maximum segment to pack data to * @data: data to pack into scatter/gather list * @count: amount of data to pack into the scatter/gather list * * sg_lists have multiple segments of various sizes. This will pack * arbitrary data into an existing scatter gather list, segmenting the * data as necessary within constraints. * */
static int pack_sg_list(struct scatterlist *sg, int start, int limit, char *data, int count) { int s; int index = start; while (count) { s = rest_of_page(data); if (s > count) s = count; BUG_ON(index > limit); /* Make sure we don't terminate early. */ sg_unmark_end(&sg[index]); sg_set_buf(&sg[index++], data, s); count -= s; data += s; } if (index-start) sg_mark_end(&sg[index - 1]); return index-start; }

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PersonTokensPropCommitsCommitProp
eric van hensbergeneric van hensbergen8270.69%250.00%
rusty russellrusty russell2723.28%125.00%
sasha levinsasha levin76.03%125.00%
Total116100.00%4100.00%

/* We don't currently allow canceling of virtio requests */
static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req) { return 1; }

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eric van hensbergeneric van hensbergen19100.00%4100.00%
Total19100.00%4100.00%

/** * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer, * this takes a list of pages. * @sg: scatter/gather list to pack into * @start: which segment of the sg_list to start at * @pdata: a list of pages to add into sg. * @nr_pages: number of pages to pack into the scatter/gather list * @offs: amount of data in the beginning of first page _not_ to pack * @count: amount of data to pack into the scatter/gather list */
static int pack_sg_list_p(struct scatterlist *sg, int start, int limit, struct page **pdata, int nr_pages, size_t offs, int count) { int i = 0, s; int data_off = offs; int index = start; BUG_ON(nr_pages > (limit - start)); /* * if the first page doesn't start at * page boundary find the offset */ while (nr_pages) { s = PAGE_SIZE - data_off; if (s > count) s = count; /* Make sure we don't terminate early. */ sg_unmark_end(&sg[index]); sg_set_page(&sg[index++], pdata[i++], s, data_off); data_off = 0; count -= s; nr_pages--; } if (index-start) sg_mark_end(&sg[index - 1]); return index - start; }

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venkateswararao jujjurivenkateswararao jujjuri7853.42%125.00%
aneesh kumaraneesh kumar3423.29%125.00%
rusty russellrusty russell2718.49%125.00%
al viroal viro74.79%125.00%
Total146100.00%4100.00%

/** * p9_virtio_request - issue a request * @client: client instance issuing the request * @req: request to be issued * */
static int p9_virtio_request(struct p9_client *client, struct p9_req_t *req) { int err; int in, out, out_sgs, in_sgs; unsigned long flags; struct virtio_chan *chan = client->trans; struct scatterlist *sgs[2]; p9_debug(P9_DEBUG_TRANS, "9p debug: virtio request\n"); req->status = REQ_STATUS_SENT; req_retry: spin_lock_irqsave(&chan->lock, flags); out_sgs = in_sgs = 0; /* Handle out VirtIO ring buffers */ out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata, req->tc->size); if (out) sgs[out_sgs++] = chan->sg; in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, req->rc->sdata, req->rc->capacity); if (in) sgs[out_sgs + in_sgs++] = chan->sg + out; err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req, GFP_ATOMIC); if (err < 0) { if (err == -ENOSPC) { chan->ring_bufs_avail = 0; spin_unlock_irqrestore(&chan->lock, flags); err = wait_event_interruptible(*chan->vc_wq, chan->ring_bufs_avail); if (err == -ERESTARTSYS) return err; p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); goto req_retry; } else { spin_unlock_irqrestore(&chan->lock, flags); p9_debug(P9_DEBUG_TRANS, "virtio rpc add_sgs returned failure\n"); return -EIO; } } virtqueue_kick(chan->vq); spin_unlock_irqrestore(&chan->lock, flags); p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); return 0; }

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PersonTokensPropCommitsCommitProp
aneesh kumaraneesh kumar12040.00%216.67%
venkateswararao jujjurivenkateswararao jujjuri7725.67%325.00%
rusty russellrusty russell5719.00%216.67%
eric van hensbergeneric van hensbergen4013.33%433.33%
joe perchesjoe perches62.00%18.33%
Total300100.00%12100.00%


static int p9_get_mapped_pages(struct virtio_chan *chan, struct page ***pages, struct iov_iter *data, int count, size_t *offs, int *need_drop) { int nr_pages; int err; if (!iov_iter_count(data)) return 0; if (!(data->type & ITER_KVEC)) { int n; /* * We allow only p9_max_pages pinned. We wait for the * Other zc request to finish here */ if (atomic_read(&vp_pinned) >= chan->p9_max_pages) { err = wait_event_interruptible(vp_wq, (atomic_read(&vp_pinned) < chan->p9_max_pages)); if (err == -ERESTARTSYS) return err; } n = iov_iter_get_pages_alloc(data, pages, count, offs); if (n < 0) return n; *need_drop = 1; nr_pages = DIV_ROUND_UP(n + *offs, PAGE_SIZE); atomic_add(nr_pages, &vp_pinned); return n; } else { /* kernel buffer, no need to pin pages */ int index; size_t len; void *p; /* we'd already checked that it's non-empty */ while (1) { len = iov_iter_single_seg_count(data); if (likely(len)) { p = data->kvec->iov_base + data->iov_offset; break; } iov_iter_advance(data, 0); } if (len > count) len = count; nr_pages = DIV_ROUND_UP((unsigned long)p + len, PAGE_SIZE) - (unsigned long)p / PAGE_SIZE; *pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_NOFS); if (!*pages) return -ENOMEM; *need_drop = 0; p -= (*offs = offset_in_page(p)); for (index = 0; index < nr_pages; index++) { if (is_vmalloc_addr(p)) (*pages)[index] = vmalloc_to_page(p); else (*pages)[index] = kmap_to_page(p); p += PAGE_SIZE; } return len; } }

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PersonTokensPropCommitsCommitProp
al viroal viro20458.12%233.33%
aneesh kumaraneesh kumar13037.04%233.33%
richard yaorichard yao164.56%116.67%
will deaconwill deacon10.28%116.67%
Total351100.00%6100.00%

/** * p9_virtio_zc_request - issue a zero copy request * @client: client instance issuing the request * @req: request to be issued * @uidata: user bffer that should be ued for zero copy read * @uodata: user buffer that shoud be user for zero copy write * @inlen: read buffer size * @olen: write buffer size * @hdrlen: reader header size, This is the size of response protocol data * */
static int p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req, struct iov_iter *uidata, struct iov_iter *uodata, int inlen, int outlen, int in_hdr_len) { int in, out, err, out_sgs, in_sgs; unsigned long flags; int in_nr_pages = 0, out_nr_pages = 0; struct page **in_pages = NULL, **out_pages = NULL; struct virtio_chan *chan = client->trans; struct scatterlist *sgs[4]; size_t offs; int need_drop = 0; p9_debug(P9_DEBUG_TRANS, "virtio request\n"); if (uodata) { int n = p9_get_mapped_pages(chan, &out_pages, uodata, outlen, &offs, &need_drop); if (n < 0) return n; out_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE); if (n != outlen) { __le32 v = cpu_to_le32(n); memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4); outlen = n; } } else if (uidata) { int n = p9_get_mapped_pages(chan, &in_pages, uidata, inlen, &offs, &need_drop); if (n < 0) return n; in_nr_pages = DIV_ROUND_UP(n + offs, PAGE_SIZE); if (n != inlen) { __le32 v = cpu_to_le32(n); memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4); inlen = n; } } req->status = REQ_STATUS_SENT; req_retry_pinned: spin_lock_irqsave(&chan->lock, flags); out_sgs = in_sgs = 0; /* out data */ out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata, req->tc->size); if (out) sgs[out_sgs++] = chan->sg; if (out_pages) { sgs[out_sgs++] = chan->sg + out; out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM, out_pages, out_nr_pages, offs, outlen); } /* * Take care of in data * For example TREAD have 11. * 11 is the read/write header = PDU Header(7) + IO Size (4). * Arrange in such a way that server places header in the * alloced memory and payload onto the user buffer. */ in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, req->rc->sdata, in_hdr_len); if (in) sgs[out_sgs + in_sgs++] = chan->sg + out; if (in_pages) { sgs[out_sgs + in_sgs++] = chan->sg + out + in; in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM, in_pages, in_nr_pages, offs, inlen); } BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs)); err = virtqueue_add_sgs(chan->vq, sgs, out_sgs, in_sgs, req, GFP_ATOMIC); if (err < 0) { if (err == -ENOSPC) { chan->ring_bufs_avail = 0; spin_unlock_irqrestore(&chan->lock, flags); err = wait_event_interruptible(*chan->vc_wq, chan->ring_bufs_avail); if (err == -ERESTARTSYS) goto err_out; p9_debug(P9_DEBUG_TRANS, "Retry virtio request\n"); goto req_retry_pinned; } else { spin_unlock_irqrestore(&chan->lock, flags); p9_debug(P9_DEBUG_TRANS, "virtio rpc add_sgs returned failure\n"); err = -EIO; goto err_out; } } virtqueue_kick(chan->vq); spin_unlock_irqrestore(&chan->lock, flags); p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n"); err = wait_event_interruptible(*req->wq, req->status >= REQ_STATUS_RCVD); /* * Non kernel buffers are pinned, unpin them */ err_out: if (need_drop) { if (in_pages) { p9_release_pages(in_pages, in_nr_pages); atomic_sub(in_nr_pages, &vp_pinned); } if (out_pages) { p9_release_pages(out_pages, out_nr_pages); atomic_sub(out_nr_pages, &vp_pinned); } /* wakeup anybody waiting for slots to pin pages */ wake_up(&vp_wq); } kvfree(in_pages); kvfree(out_pages); return err; }

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PersonTokensPropCommitsCommitProp
aneesh kumaraneesh kumar27438.43%211.76%
venkateswararao jujjurivenkateswararao jujjuri15321.46%423.53%
al viroal viro13418.79%15.88%
rusty russellrusty russell10314.45%317.65%
eric van hensbergeneric van hensbergen395.47%423.53%
joe perchesjoe perches70.98%15.88%
vegard nossumvegard nossum20.28%15.88%
michael s. tsirkinmichael s. tsirkin10.14%15.88%
Total713100.00%17100.00%


static ssize_t p9_mount_tag_show(struct device *dev, struct device_attribute *attr, char *buf) { struct virtio_chan *chan; struct virtio_device *vdev; vdev = dev_to_virtio(dev); chan = vdev->priv; memcpy(buf, chan->tag, chan->tag_len); buf[chan->tag_len] = 0; return chan->tag_len + 1; }

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aneesh kumaraneesh kumar5373.61%150.00%
andrey ryabininandrey ryabinin1926.39%150.00%
Total72100.00%2100.00%

static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL); /** * p9_virtio_probe - probe for existence of 9P virtio channels * @vdev: virtio device to probe * * This probes for existing virtio channels. * */
static int p9_virtio_probe(struct virtio_device *vdev) { __u16 tag_len; char *tag; int err; struct virtio_chan *chan; if (!vdev->config->get) { dev_err(&vdev->dev, "%s failure: config access disabled\n", __func__); return -EINVAL; } chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL); if (!chan) { pr_err("Failed to allocate virtio 9P channel\n"); err = -ENOMEM; goto fail; } chan->vdev = vdev; /* We expect one virtqueue, for requests. */ chan->vq = virtio_find_single_vq(vdev, req_done, "requests"); if (IS_ERR(chan->vq)) { err = PTR_ERR(chan->vq); goto out_free_vq; } chan->vq->vdev->priv = chan; spin_lock_init(&chan->lock); sg_init_table(chan->sg, VIRTQUEUE_NUM); chan->inuse = false; if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) { virtio_cread(vdev, struct virtio_9p_config, tag_len, &tag_len); } else { err = -EINVAL; goto out_free_vq; } tag = kmalloc(tag_len, GFP_KERNEL); if (!tag) { err = -ENOMEM; goto out_free_vq; } virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag), tag, tag_len); chan->tag = tag; chan->tag_len = tag_len; err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); if (err) { goto out_free_tag; } chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL); if (!chan->vc_wq) { err = -ENOMEM; goto out_free_tag; } init_waitqueue_head(chan->vc_wq); chan->ring_bufs_avail = 1; /* Ceiling limit to avoid denial of service attacks */ chan->p9_max_pages = nr_free_buffer_pages()/4; virtio_device_ready(vdev); mutex_lock(&virtio_9p_lock); list_add_tail(&chan->chan_list, &virtio_chan_list); mutex_unlock(&virtio_9p_lock); /* Let udev rules use the new mount_tag attribute. */ kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE); return 0; out_free_tag: kfree(tag); out_free_vq: vdev->config->del_vqs(vdev); kfree(chan); fail: return err; }

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PersonTokensPropCommitsCommitProp
aneesh kumaraneesh kumar15738.67%321.43%
eric van hensbergeneric van hensbergen13433.00%214.29%
venkateswararao jujjurivenkateswararao jujjuri5914.53%214.29%
michael s. tsirkinmichael s. tsirkin358.62%321.43%
michael marineaumichael marineau153.69%17.14%
rusty russellrusty russell40.99%214.29%
joe perchesjoe perches20.49%17.14%
Total406100.00%14100.00%

/** * p9_virtio_create - allocate a new virtio channel * @client: client instance invoking this transport * @devname: string identifying the channel to connect to (unused) * @args: args passed from sys_mount() for per-transport options (unused) * * This sets up a transport channel for 9p communication. Right now * we only match the first available channel, but eventually we couldlook up * alternate channels by matching devname versus a virtio_config entry. * We use a simple reference count mechanism to ensure that only a single * mount has a channel open at a time. * */
static int p9_virtio_create(struct p9_client *client, const char *devname, char *args) { struct virtio_chan *chan; int ret = -ENOENT; int found = 0; mutex_lock(&virtio_9p_lock); list_for_each_entry(chan, &virtio_chan_list, chan_list) { if (!strncmp(devname, chan->tag, chan->tag_len) && strlen(devname) == chan->tag_len) { if (!chan->inuse) { chan->inuse = true; found = 1; break; } ret = -EBUSY; } } mutex_unlock(&virtio_9p_lock); if (!found) { pr_err("no channels available for device %s\n", devname); return ret; } client->trans = (void *)chan; client->status = Connected; chan->client = client; return 0; }

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eric van hensbergeneric van hensbergen9260.53%538.46%
aneesh kumaraneesh kumar4831.58%538.46%
sven eckelmannsven eckelmann95.92%17.69%
josef sipekjosef sipek21.32%17.69%
joe perchesjoe perches10.66%17.69%
Total152100.00%13100.00%

/** * p9_virtio_remove - clean up resources associated with a virtio device * @vdev: virtio device to remove * */
static void p9_virtio_remove(struct virtio_device *vdev) { struct virtio_chan *chan = vdev->priv; unsigned long warning_time; mutex_lock(&virtio_9p_lock); /* Remove self from list so we don't get new users. */ list_del(&chan->chan_list); warning_time = jiffies; /* Wait for existing users to close. */ while (chan->inuse) { mutex_unlock(&virtio_9p_lock); msleep(250); if (time_after(jiffies, warning_time + 10 * HZ)) { dev_emerg(&vdev->dev, "p9_virtio_remove: waiting for device in use.\n"); warning_time = jiffies; } mutex_lock(&virtio_9p_lock); } mutex_unlock(&virtio_9p_lock); vdev->config->reset(vdev); vdev->config->del_vqs(vdev); sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr); kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE); kfree(chan->tag); kfree(chan->vc_wq); kfree(chan); }

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PersonTokensPropCommitsCommitProp
michael s. tsirkinmichael s. tsirkin6839.53%111.11%
aneesh kumaraneesh kumar4224.42%333.33%
eric van hensbergeneric van hensbergen2916.86%111.11%
michael marineaumichael marineau148.14%111.11%
pierre morelpierre morel95.23%111.11%
venkateswararao jujjurivenkateswararao jujjuri74.07%111.11%
sasha levinsasha levin31.74%111.11%
Total172100.00%9100.00%

static struct virtio_device_id id_table[] = { { VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID }, { 0 }, }; static unsigned int features[] = { VIRTIO_9P_MOUNT_TAG, }; /* The standard "struct lguest_driver": */ static struct virtio_driver p9_virtio_drv = { .feature_table = features, .feature_table_size = ARRAY_SIZE(features), .driver.name = KBUILD_MODNAME, .driver.owner = THIS_MODULE, .id_table = id_table, .probe = p9_virtio_probe, .remove = p9_virtio_remove, }; static struct