aboutsummaryrefslogtreecommitdiffstats
path: root/net/9p/trans_virtio.c
diff options
context:
space:
mode:
Diffstat (limited to 'net/9p/trans_virtio.c')
-rw-r--r--net/9p/trans_virtio.c136
1 files changed, 9 insertions, 127 deletions
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index 72493f04a76d..36bce45e4e44 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -1,12 +1,10 @@
1/* 1/*
2 * The Guest 9p transport driver 2 * The Virtio 9p transport driver
3 * 3 *
4 * This is a block based transport driver based on the lguest block driver 4 * This is a block based transport driver based on the lguest block driver
5 * code. 5 * code.
6 * 6 *
7 */ 7 * Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
8/*
9 * Copyright (C) 2007 Eric Van Hensbergen, IBM Corporation
10 * 8 *
11 * Based on virtio console driver 9 * Based on virtio console driver
12 * Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation 10 * Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
@@ -54,49 +52,6 @@ static DEFINE_MUTEX(virtio_9p_lock);
54/* global which tracks highest initialized channel */ 52/* global which tracks highest initialized channel */
55static int chan_index; 53static int chan_index;
56 54
57#define P9_INIT_MAXTAG 16
58
59/**
60 * enum p9_req_status_t - virtio request status
61 * @REQ_STATUS_IDLE: request slot unused
62 * @REQ_STATUS_SENT: request sent to server
63 * @REQ_STATUS_RCVD: response received from server
64 * @REQ_STATUS_FLSH: request has been flushed
65 *
66 * The @REQ_STATUS_IDLE state is used to mark a request slot as unused
67 * but use is actually tracked by the idpool structure which handles tag
68 * id allocation.
69 *
70 */
71
72enum p9_req_status_t {
73 REQ_STATUS_IDLE,
74 REQ_STATUS_SENT,
75 REQ_STATUS_RCVD,
76 REQ_STATUS_FLSH,
77};
78
79/**
80 * struct p9_req_t - virtio request slots
81 * @status: status of this request slot
82 * @wq: wait_queue for the client to block on for this request
83 *
84 * The virtio transport uses an array to track outstanding requests
85 * instead of a list. While this may incurr overhead during initial
86 * allocation or expansion, it makes request lookup much easier as the
87 * tag id is a index into an array. (We use tag+1 so that we can accomodate
88 * the -1 tag for the T_VERSION request).
89 * This also has the nice effect of only having to allocate wait_queues
90 * once, instead of constantly allocating and freeing them. Its possible
91 * other resources could benefit from this scheme as well.
92 *
93 */
94
95struct p9_req_t {
96 int status;
97 wait_queue_head_t *wq;
98};
99
100/** 55/**
101 * struct virtio_chan - per-instance transport information 56 * struct virtio_chan - per-instance transport information
102 * @initialized: whether the channel is initialized 57 * @initialized: whether the channel is initialized
@@ -121,67 +76,14 @@ static struct virtio_chan {
121 76
122 spinlock_t lock; 77 spinlock_t lock;
123 78
79 struct p9_client *client;
124 struct virtio_device *vdev; 80 struct virtio_device *vdev;
125 struct virtqueue *vq; 81 struct virtqueue *vq;
126 82
127 struct p9_idpool *tagpool;
128 struct p9_req_t *reqs;
129 int max_tag;
130
131 /* Scatterlist: can be too big for stack. */ 83 /* Scatterlist: can be too big for stack. */
132 struct scatterlist sg[VIRTQUEUE_NUM]; 84 struct scatterlist sg[VIRTQUEUE_NUM];
133} channels[MAX_9P_CHAN]; 85} channels[MAX_9P_CHAN];
134 86
135/**
136 * p9_lookup_tag - Lookup requests by tag
137 * @c: virtio channel to lookup tag within
138 * @tag: numeric id for transaction
139 *
140 * this is a simple array lookup, but will grow the
141 * request_slots as necessary to accomodate transaction
142 * ids which did not previously have a slot.
143 *
144 * Bugs: there is currently no upper limit on request slots set
145 * here, but that should be constrained by the id accounting.
146 */
147
148static struct p9_req_t *p9_lookup_tag(struct virtio_chan *c, u16 tag)
149{
150 /* This looks up the original request by tag so we know which
151 * buffer to read the data into */
152 tag++;
153
154 while (tag >= c->max_tag) {
155 int old_max = c->max_tag;
156 int count;
157
158 if (c->max_tag)
159 c->max_tag *= 2;
160 else
161 c->max_tag = P9_INIT_MAXTAG;
162
163 c->reqs = krealloc(c->reqs, sizeof(struct p9_req_t)*c->max_tag,
164 GFP_ATOMIC);
165 if (!c->reqs) {
166 printk(KERN_ERR "Couldn't grow tag array\n");
167 BUG();
168 }
169 for (count = old_max; count < c->max_tag; count++) {
170 c->reqs[count].status = REQ_STATUS_IDLE;
171 c->reqs[count].wq = kmalloc(sizeof(wait_queue_head_t),
172 GFP_ATOMIC);
173 if (!c->reqs[count].wq) {
174 printk(KERN_ERR "Couldn't grow tag array\n");
175 BUG();
176 }
177 init_waitqueue_head(c->reqs[count].wq);
178 }
179 }
180
181 return &c->reqs[tag];
182}
183
184
185/* How many bytes left in this page. */ 87/* How many bytes left in this page. */
186static unsigned int rest_of_page(void *data) 88static unsigned int rest_of_page(void *data)
187{ 89{
@@ -200,22 +102,10 @@ static unsigned int rest_of_page(void *data)
200static void p9_virtio_close(struct p9_client *client) 102static void p9_virtio_close(struct p9_client *client)
201{ 103{
202 struct virtio_chan *chan = client->trans; 104 struct virtio_chan *chan = client->trans;
203 int count;
204 unsigned long flags;
205
206 spin_lock_irqsave(&chan->lock, flags);
207 p9_idpool_destroy(chan->tagpool);
208 for (count = 0; count < chan->max_tag; count++)
209 kfree(chan->reqs[count].wq);
210 kfree(chan->reqs);
211 chan->max_tag = 0;
212 spin_unlock_irqrestore(&chan->lock, flags);
213 105
214 mutex_lock(&virtio_9p_lock); 106 mutex_lock(&virtio_9p_lock);
215 chan->inuse = false; 107 chan->inuse = false;
216 mutex_unlock(&virtio_9p_lock); 108 mutex_unlock(&virtio_9p_lock);
217
218 client->trans = NULL;
219} 109}
220 110
221/** 111/**
@@ -241,7 +131,7 @@ static void req_done(struct virtqueue *vq)
241 131
242 spin_lock_irqsave(&chan->lock, flags); 132 spin_lock_irqsave(&chan->lock, flags);
243 while ((rc = chan->vq->vq_ops->get_buf(chan->vq, &len)) != NULL) { 133 while ((rc = chan->vq->vq_ops->get_buf(chan->vq, &len)) != NULL) {
244 req = p9_lookup_tag(chan, rc->tag); 134 req = p9_tag_lookup(chan->client, rc->tag);
245 req->status = REQ_STATUS_RCVD; 135 req->status = REQ_STATUS_RCVD;
246 wake_up(req->wq); 136 wake_up(req->wq);
247 } 137 }
@@ -311,13 +201,13 @@ p9_virtio_rpc(struct p9_client *c, struct p9_fcall *tc, struct p9_fcall **rc)
311 201
312 n = P9_NOTAG; 202 n = P9_NOTAG;
313 if (tc->id != P9_TVERSION) { 203 if (tc->id != P9_TVERSION) {
314 n = p9_idpool_get(chan->tagpool); 204 n = p9_idpool_get(c->tagpool);
315 if (n < 0) 205 if (n < 0)
316 return -ENOMEM; 206 return -ENOMEM;
317 } 207 }
318 208
319 spin_lock_irqsave(&chan->lock, flags); 209 spin_lock_irqsave(&chan->lock, flags);
320 req = p9_lookup_tag(chan, n); 210 req = p9_tag_alloc(c, n);
321 spin_unlock_irqrestore(&chan->lock, flags); 211 spin_unlock_irqrestore(&chan->lock, flags);
322 212
323 p9_set_tag(tc, n); 213 p9_set_tag(tc, n);
@@ -357,8 +247,8 @@ p9_virtio_rpc(struct p9_client *c, struct p9_fcall *tc, struct p9_fcall **rc)
357 } 247 }
358#endif 248#endif
359 249
360 if (n != P9_NOTAG && p9_idpool_check(n, chan->tagpool)) 250 if (n != P9_NOTAG && p9_idpool_check(n, c->tagpool))
361 p9_idpool_put(n, chan->tagpool); 251 p9_idpool_put(n, c->tagpool);
362 252
363 req->status = REQ_STATUS_IDLE; 253 req->status = REQ_STATUS_IDLE;
364 254
@@ -463,16 +353,8 @@ p9_virtio_create(struct p9_client *client, const char *devname, char *args)
463 return -ENODEV; 353 return -ENODEV;
464 } 354 }
465 355
466 chan->tagpool = p9_idpool_create();
467 if (IS_ERR(chan->tagpool)) {
468 printk(KERN_ERR "9p: couldn't allocate tagpool\n");
469 return -ENOMEM;
470 }
471 p9_idpool_get(chan->tagpool); /* reserve tag 0 */
472 chan->max_tag = 0;
473 chan->reqs = NULL;
474
475 client->trans = (void *)chan; 356 client->trans = (void *)chan;
357 chan->client = client;
476 358
477 return 0; 359 return 0;
478} 360}