Loading...
1/******************************************************************************
2
3(c) 2007 Network Appliance, Inc. All Rights Reserved.
4(c) 2009 NetApp. All Rights Reserved.
5
6NetApp provides this source code under the GPL v2 License.
7The GPL v2 license is available at
8http://opensource.org/licenses/gpl-license.php.
9
10THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
11"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
12LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
13A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
14CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
15EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
16PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
17PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
18LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
19NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
20SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
21
22******************************************************************************/
23
24#include <linux/tcp.h>
25#include <linux/slab.h>
26#include <linux/sunrpc/xprt.h>
27#include <linux/export.h>
28#include <linux/sunrpc/bc_xprt.h>
29
30#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
31#define RPCDBG_FACILITY RPCDBG_TRANS
32#endif
33
34#define BC_MAX_SLOTS 64U
35
36unsigned int xprt_bc_max_slots(struct rpc_xprt *xprt)
37{
38 return BC_MAX_SLOTS;
39}
40
41/*
42 * Helper routines that track the number of preallocation elements
43 * on the transport.
44 */
45static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
46{
47 return xprt->bc_alloc_count < xprt->bc_alloc_max;
48}
49
50/*
51 * Free the preallocated rpc_rqst structure and the memory
52 * buffers hanging off of it.
53 */
54static void xprt_free_allocation(struct rpc_rqst *req)
55{
56 struct xdr_buf *xbufp;
57
58 dprintk("RPC: free allocations for req= %p\n", req);
59 WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
60 xbufp = &req->rq_rcv_buf;
61 free_page((unsigned long)xbufp->head[0].iov_base);
62 xbufp = &req->rq_snd_buf;
63 free_page((unsigned long)xbufp->head[0].iov_base);
64 kfree(req);
65}
66
67static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags)
68{
69 struct page *page;
70 /* Preallocate one XDR receive buffer */
71 page = alloc_page(gfp_flags);
72 if (page == NULL)
73 return -ENOMEM;
74 xdr_buf_init(buf, page_address(page), PAGE_SIZE);
75 return 0;
76}
77
78static
79struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt, gfp_t gfp_flags)
80{
81 struct rpc_rqst *req;
82
83 /* Pre-allocate one backchannel rpc_rqst */
84 req = kzalloc(sizeof(*req), gfp_flags);
85 if (req == NULL)
86 return NULL;
87
88 req->rq_xprt = xprt;
89 INIT_LIST_HEAD(&req->rq_bc_list);
90
91 /* Preallocate one XDR receive buffer */
92 if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) {
93 printk(KERN_ERR "Failed to create bc receive xbuf\n");
94 goto out_free;
95 }
96 req->rq_rcv_buf.len = PAGE_SIZE;
97
98 /* Preallocate one XDR send buffer */
99 if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) {
100 printk(KERN_ERR "Failed to create bc snd xbuf\n");
101 goto out_free;
102 }
103 return req;
104out_free:
105 xprt_free_allocation(req);
106 return NULL;
107}
108
109/*
110 * Preallocate up to min_reqs structures and related buffers for use
111 * by the backchannel. This function can be called multiple times
112 * when creating new sessions that use the same rpc_xprt. The
113 * preallocated buffers are added to the pool of resources used by
114 * the rpc_xprt. Anyone of these resources may be used used by an
115 * incoming callback request. It's up to the higher levels in the
116 * stack to enforce that the maximum number of session slots is not
117 * being exceeded.
118 *
119 * Some callback arguments can be large. For example, a pNFS server
120 * using multiple deviceids. The list can be unbound, but the client
121 * has the ability to tell the server the maximum size of the callback
122 * requests. Each deviceID is 16 bytes, so allocate one page
123 * for the arguments to have enough room to receive a number of these
124 * deviceIDs. The NFS client indicates to the pNFS server that its
125 * callback requests can be up to 4096 bytes in size.
126 */
127int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs)
128{
129 if (!xprt->ops->bc_setup)
130 return 0;
131 return xprt->ops->bc_setup(xprt, min_reqs);
132}
133EXPORT_SYMBOL_GPL(xprt_setup_backchannel);
134
135int xprt_setup_bc(struct rpc_xprt *xprt, unsigned int min_reqs)
136{
137 struct rpc_rqst *req;
138 struct list_head tmp_list;
139 int i;
140
141 dprintk("RPC: setup backchannel transport\n");
142
143 if (min_reqs > BC_MAX_SLOTS)
144 min_reqs = BC_MAX_SLOTS;
145
146 /*
147 * We use a temporary list to keep track of the preallocated
148 * buffers. Once we're done building the list we splice it
149 * into the backchannel preallocation list off of the rpc_xprt
150 * struct. This helps minimize the amount of time the list
151 * lock is held on the rpc_xprt struct. It also makes cleanup
152 * easier in case of memory allocation errors.
153 */
154 INIT_LIST_HEAD(&tmp_list);
155 for (i = 0; i < min_reqs; i++) {
156 /* Pre-allocate one backchannel rpc_rqst */
157 req = xprt_alloc_bc_req(xprt, GFP_KERNEL);
158 if (req == NULL) {
159 printk(KERN_ERR "Failed to create bc rpc_rqst\n");
160 goto out_free;
161 }
162
163 /* Add the allocated buffer to the tmp list */
164 dprintk("RPC: adding req= %p\n", req);
165 list_add(&req->rq_bc_pa_list, &tmp_list);
166 }
167
168 /*
169 * Add the temporary list to the backchannel preallocation list
170 */
171 spin_lock(&xprt->bc_pa_lock);
172 list_splice(&tmp_list, &xprt->bc_pa_list);
173 xprt->bc_alloc_count += min_reqs;
174 xprt->bc_alloc_max += min_reqs;
175 atomic_add(min_reqs, &xprt->bc_slot_count);
176 spin_unlock(&xprt->bc_pa_lock);
177
178 dprintk("RPC: setup backchannel transport done\n");
179 return 0;
180
181out_free:
182 /*
183 * Memory allocation failed, free the temporary list
184 */
185 while (!list_empty(&tmp_list)) {
186 req = list_first_entry(&tmp_list,
187 struct rpc_rqst,
188 rq_bc_pa_list);
189 list_del(&req->rq_bc_pa_list);
190 xprt_free_allocation(req);
191 }
192
193 dprintk("RPC: setup backchannel transport failed\n");
194 return -ENOMEM;
195}
196
197/**
198 * xprt_destroy_backchannel - Destroys the backchannel preallocated structures.
199 * @xprt: the transport holding the preallocated strucures
200 * @max_reqs: the maximum number of preallocated structures to destroy
201 *
202 * Since these structures may have been allocated by multiple calls
203 * to xprt_setup_backchannel, we only destroy up to the maximum number
204 * of reqs specified by the caller.
205 */
206void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
207{
208 if (xprt->ops->bc_destroy)
209 xprt->ops->bc_destroy(xprt, max_reqs);
210}
211EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);
212
213void xprt_destroy_bc(struct rpc_xprt *xprt, unsigned int max_reqs)
214{
215 struct rpc_rqst *req = NULL, *tmp = NULL;
216
217 dprintk("RPC: destroy backchannel transport\n");
218
219 if (max_reqs == 0)
220 goto out;
221
222 spin_lock_bh(&xprt->bc_pa_lock);
223 xprt->bc_alloc_max -= min(max_reqs, xprt->bc_alloc_max);
224 list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
225 dprintk("RPC: req=%p\n", req);
226 list_del(&req->rq_bc_pa_list);
227 xprt_free_allocation(req);
228 xprt->bc_alloc_count--;
229 atomic_dec(&xprt->bc_slot_count);
230 if (--max_reqs == 0)
231 break;
232 }
233 spin_unlock_bh(&xprt->bc_pa_lock);
234
235out:
236 dprintk("RPC: backchannel list empty= %s\n",
237 list_empty(&xprt->bc_pa_list) ? "true" : "false");
238}
239
240static struct rpc_rqst *xprt_get_bc_request(struct rpc_xprt *xprt, __be32 xid,
241 struct rpc_rqst *new)
242{
243 struct rpc_rqst *req = NULL;
244
245 dprintk("RPC: allocate a backchannel request\n");
246 if (list_empty(&xprt->bc_pa_list)) {
247 if (!new)
248 goto not_found;
249 if (atomic_read(&xprt->bc_slot_count) >= BC_MAX_SLOTS)
250 goto not_found;
251 list_add_tail(&new->rq_bc_pa_list, &xprt->bc_pa_list);
252 xprt->bc_alloc_count++;
253 atomic_inc(&xprt->bc_slot_count);
254 }
255 req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
256 rq_bc_pa_list);
257 req->rq_reply_bytes_recvd = 0;
258 memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
259 sizeof(req->rq_private_buf));
260 req->rq_xid = xid;
261 req->rq_connect_cookie = xprt->connect_cookie;
262 dprintk("RPC: backchannel req=%p\n", req);
263not_found:
264 return req;
265}
266
267/*
268 * Return the preallocated rpc_rqst structure and XDR buffers
269 * associated with this rpc_task.
270 */
271void xprt_free_bc_request(struct rpc_rqst *req)
272{
273 struct rpc_xprt *xprt = req->rq_xprt;
274
275 xprt->ops->bc_free_rqst(req);
276}
277
278void xprt_free_bc_rqst(struct rpc_rqst *req)
279{
280 struct rpc_xprt *xprt = req->rq_xprt;
281
282 dprintk("RPC: free backchannel req=%p\n", req);
283
284 req->rq_connect_cookie = xprt->connect_cookie - 1;
285 smp_mb__before_atomic();
286 clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
287 smp_mb__after_atomic();
288
289 /*
290 * Return it to the list of preallocations so that it
291 * may be reused by a new callback request.
292 */
293 spin_lock_bh(&xprt->bc_pa_lock);
294 if (xprt_need_to_requeue(xprt)) {
295 list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
296 xprt->bc_alloc_count++;
297 atomic_inc(&xprt->bc_slot_count);
298 req = NULL;
299 }
300 spin_unlock_bh(&xprt->bc_pa_lock);
301 if (req != NULL) {
302 /*
303 * The last remaining session was destroyed while this
304 * entry was in use. Free the entry and don't attempt
305 * to add back to the list because there is no need to
306 * have anymore preallocated entries.
307 */
308 dprintk("RPC: Last session removed req=%p\n", req);
309 xprt_free_allocation(req);
310 }
311 xprt_put(xprt);
312}
313
314/*
315 * One or more rpc_rqst structure have been preallocated during the
316 * backchannel setup. Buffer space for the send and private XDR buffers
317 * has been preallocated as well. Use xprt_alloc_bc_request to allocate
318 * to this request. Use xprt_free_bc_request to return it.
319 *
320 * We know that we're called in soft interrupt context, grab the spin_lock
321 * since there is no need to grab the bottom half spin_lock.
322 *
323 * Return an available rpc_rqst, otherwise NULL if non are available.
324 */
325struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid)
326{
327 struct rpc_rqst *req, *new = NULL;
328
329 do {
330 spin_lock(&xprt->bc_pa_lock);
331 list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) {
332 if (req->rq_connect_cookie != xprt->connect_cookie)
333 continue;
334 if (req->rq_xid == xid)
335 goto found;
336 }
337 req = xprt_get_bc_request(xprt, xid, new);
338found:
339 spin_unlock(&xprt->bc_pa_lock);
340 if (new) {
341 if (req != new)
342 xprt_free_allocation(new);
343 break;
344 } else if (req)
345 break;
346 new = xprt_alloc_bc_req(xprt, GFP_KERNEL);
347 } while (new);
348 return req;
349}
350
351/*
352 * Add callback request to callback list. The callback
353 * service sleeps on the sv_cb_waitq waiting for new
354 * requests. Wake it up after adding enqueing the
355 * request.
356 */
357void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
358{
359 struct rpc_xprt *xprt = req->rq_xprt;
360 struct svc_serv *bc_serv = xprt->bc_serv;
361
362 spin_lock(&xprt->bc_pa_lock);
363 list_del(&req->rq_bc_pa_list);
364 xprt->bc_alloc_count--;
365 spin_unlock(&xprt->bc_pa_lock);
366
367 req->rq_private_buf.len = copied;
368 set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
369
370 dprintk("RPC: add callback request to list\n");
371 xprt_get(xprt);
372 spin_lock(&bc_serv->sv_cb_lock);
373 list_add(&req->rq_bc_list, &bc_serv->sv_cb_list);
374 wake_up(&bc_serv->sv_cb_waitq);
375 spin_unlock(&bc_serv->sv_cb_lock);
376}
1/******************************************************************************
2
3(c) 2007 Network Appliance, Inc. All Rights Reserved.
4(c) 2009 NetApp. All Rights Reserved.
5
6NetApp provides this source code under the GPL v2 License.
7The GPL v2 license is available at
8http://opensource.org/licenses/gpl-license.php.
9
10THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
11"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
12LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
13A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
14CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
15EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
16PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
17PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
18LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
19NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
20SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
21
22******************************************************************************/
23
24#include <linux/tcp.h>
25#include <linux/slab.h>
26#include <linux/sunrpc/xprt.h>
27#include <linux/export.h>
28#include <linux/sunrpc/bc_xprt.h>
29
30#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
31#define RPCDBG_FACILITY RPCDBG_TRANS
32#endif
33
34/*
35 * Helper routines that track the number of preallocation elements
36 * on the transport.
37 */
38static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
39{
40 return xprt->bc_alloc_count < atomic_read(&xprt->bc_free_slots);
41}
42
43static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n)
44{
45 atomic_add(n, &xprt->bc_free_slots);
46 xprt->bc_alloc_count += n;
47}
48
49static inline int xprt_dec_alloc_count(struct rpc_xprt *xprt, unsigned int n)
50{
51 atomic_sub(n, &xprt->bc_free_slots);
52 return xprt->bc_alloc_count -= n;
53}
54
55/*
56 * Free the preallocated rpc_rqst structure and the memory
57 * buffers hanging off of it.
58 */
59static void xprt_free_allocation(struct rpc_rqst *req)
60{
61 struct xdr_buf *xbufp;
62
63 dprintk("RPC: free allocations for req= %p\n", req);
64 WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
65 xbufp = &req->rq_rcv_buf;
66 free_page((unsigned long)xbufp->head[0].iov_base);
67 xbufp = &req->rq_snd_buf;
68 free_page((unsigned long)xbufp->head[0].iov_base);
69 kfree(req);
70}
71
72static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags)
73{
74 struct page *page;
75 /* Preallocate one XDR receive buffer */
76 page = alloc_page(gfp_flags);
77 if (page == NULL)
78 return -ENOMEM;
79 xdr_buf_init(buf, page_address(page), PAGE_SIZE);
80 return 0;
81}
82
83static
84struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt, gfp_t gfp_flags)
85{
86 struct rpc_rqst *req;
87
88 /* Pre-allocate one backchannel rpc_rqst */
89 req = kzalloc(sizeof(*req), gfp_flags);
90 if (req == NULL)
91 return NULL;
92
93 req->rq_xprt = xprt;
94 INIT_LIST_HEAD(&req->rq_list);
95 INIT_LIST_HEAD(&req->rq_bc_list);
96
97 /* Preallocate one XDR receive buffer */
98 if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) {
99 printk(KERN_ERR "Failed to create bc receive xbuf\n");
100 goto out_free;
101 }
102 req->rq_rcv_buf.len = PAGE_SIZE;
103
104 /* Preallocate one XDR send buffer */
105 if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) {
106 printk(KERN_ERR "Failed to create bc snd xbuf\n");
107 goto out_free;
108 }
109 return req;
110out_free:
111 xprt_free_allocation(req);
112 return NULL;
113}
114
115/*
116 * Preallocate up to min_reqs structures and related buffers for use
117 * by the backchannel. This function can be called multiple times
118 * when creating new sessions that use the same rpc_xprt. The
119 * preallocated buffers are added to the pool of resources used by
120 * the rpc_xprt. Anyone of these resources may be used used by an
121 * incoming callback request. It's up to the higher levels in the
122 * stack to enforce that the maximum number of session slots is not
123 * being exceeded.
124 *
125 * Some callback arguments can be large. For example, a pNFS server
126 * using multiple deviceids. The list can be unbound, but the client
127 * has the ability to tell the server the maximum size of the callback
128 * requests. Each deviceID is 16 bytes, so allocate one page
129 * for the arguments to have enough room to receive a number of these
130 * deviceIDs. The NFS client indicates to the pNFS server that its
131 * callback requests can be up to 4096 bytes in size.
132 */
133int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs)
134{
135 if (!xprt->ops->bc_setup)
136 return 0;
137 return xprt->ops->bc_setup(xprt, min_reqs);
138}
139EXPORT_SYMBOL_GPL(xprt_setup_backchannel);
140
141int xprt_setup_bc(struct rpc_xprt *xprt, unsigned int min_reqs)
142{
143 struct rpc_rqst *req;
144 struct list_head tmp_list;
145 int i;
146
147 dprintk("RPC: setup backchannel transport\n");
148
149 /*
150 * We use a temporary list to keep track of the preallocated
151 * buffers. Once we're done building the list we splice it
152 * into the backchannel preallocation list off of the rpc_xprt
153 * struct. This helps minimize the amount of time the list
154 * lock is held on the rpc_xprt struct. It also makes cleanup
155 * easier in case of memory allocation errors.
156 */
157 INIT_LIST_HEAD(&tmp_list);
158 for (i = 0; i < min_reqs; i++) {
159 /* Pre-allocate one backchannel rpc_rqst */
160 req = xprt_alloc_bc_req(xprt, GFP_KERNEL);
161 if (req == NULL) {
162 printk(KERN_ERR "Failed to create bc rpc_rqst\n");
163 goto out_free;
164 }
165
166 /* Add the allocated buffer to the tmp list */
167 dprintk("RPC: adding req= %p\n", req);
168 list_add(&req->rq_bc_pa_list, &tmp_list);
169 }
170
171 /*
172 * Add the temporary list to the backchannel preallocation list
173 */
174 spin_lock(&xprt->bc_pa_lock);
175 list_splice(&tmp_list, &xprt->bc_pa_list);
176 xprt_inc_alloc_count(xprt, min_reqs);
177 spin_unlock(&xprt->bc_pa_lock);
178
179 dprintk("RPC: setup backchannel transport done\n");
180 return 0;
181
182out_free:
183 /*
184 * Memory allocation failed, free the temporary list
185 */
186 while (!list_empty(&tmp_list)) {
187 req = list_first_entry(&tmp_list,
188 struct rpc_rqst,
189 rq_bc_pa_list);
190 list_del(&req->rq_bc_pa_list);
191 xprt_free_allocation(req);
192 }
193
194 dprintk("RPC: setup backchannel transport failed\n");
195 return -ENOMEM;
196}
197
198/**
199 * xprt_destroy_backchannel - Destroys the backchannel preallocated structures.
200 * @xprt: the transport holding the preallocated strucures
201 * @max_reqs the maximum number of preallocated structures to destroy
202 *
203 * Since these structures may have been allocated by multiple calls
204 * to xprt_setup_backchannel, we only destroy up to the maximum number
205 * of reqs specified by the caller.
206 */
207void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
208{
209 if (xprt->ops->bc_destroy)
210 xprt->ops->bc_destroy(xprt, max_reqs);
211}
212EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);
213
214void xprt_destroy_bc(struct rpc_xprt *xprt, unsigned int max_reqs)
215{
216 struct rpc_rqst *req = NULL, *tmp = NULL;
217
218 dprintk("RPC: destroy backchannel transport\n");
219
220 if (max_reqs == 0)
221 goto out;
222
223 spin_lock_bh(&xprt->bc_pa_lock);
224 xprt_dec_alloc_count(xprt, max_reqs);
225 list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
226 dprintk("RPC: req=%p\n", req);
227 list_del(&req->rq_bc_pa_list);
228 xprt_free_allocation(req);
229 if (--max_reqs == 0)
230 break;
231 }
232 spin_unlock_bh(&xprt->bc_pa_lock);
233
234out:
235 dprintk("RPC: backchannel list empty= %s\n",
236 list_empty(&xprt->bc_pa_list) ? "true" : "false");
237}
238
239static struct rpc_rqst *xprt_alloc_bc_request(struct rpc_xprt *xprt, __be32 xid)
240{
241 struct rpc_rqst *req = NULL;
242
243 dprintk("RPC: allocate a backchannel request\n");
244 if (atomic_read(&xprt->bc_free_slots) <= 0)
245 goto not_found;
246 if (list_empty(&xprt->bc_pa_list)) {
247 req = xprt_alloc_bc_req(xprt, GFP_ATOMIC);
248 if (!req)
249 goto not_found;
250 list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
251 xprt->bc_alloc_count++;
252 }
253 req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
254 rq_bc_pa_list);
255 req->rq_reply_bytes_recvd = 0;
256 req->rq_bytes_sent = 0;
257 memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
258 sizeof(req->rq_private_buf));
259 req->rq_xid = xid;
260 req->rq_connect_cookie = xprt->connect_cookie;
261not_found:
262 dprintk("RPC: backchannel req=%p\n", req);
263 return req;
264}
265
266/*
267 * Return the preallocated rpc_rqst structure and XDR buffers
268 * associated with this rpc_task.
269 */
270void xprt_free_bc_request(struct rpc_rqst *req)
271{
272 struct rpc_xprt *xprt = req->rq_xprt;
273
274 xprt->ops->bc_free_rqst(req);
275}
276
277void xprt_free_bc_rqst(struct rpc_rqst *req)
278{
279 struct rpc_xprt *xprt = req->rq_xprt;
280
281 dprintk("RPC: free backchannel req=%p\n", req);
282
283 req->rq_connect_cookie = xprt->connect_cookie - 1;
284 smp_mb__before_atomic();
285 clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
286 smp_mb__after_atomic();
287
288 /*
289 * Return it to the list of preallocations so that it
290 * may be reused by a new callback request.
291 */
292 spin_lock_bh(&xprt->bc_pa_lock);
293 if (xprt_need_to_requeue(xprt)) {
294 list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
295 xprt->bc_alloc_count++;
296 req = NULL;
297 }
298 spin_unlock_bh(&xprt->bc_pa_lock);
299 if (req != NULL) {
300 /*
301 * The last remaining session was destroyed while this
302 * entry was in use. Free the entry and don't attempt
303 * to add back to the list because there is no need to
304 * have anymore preallocated entries.
305 */
306 dprintk("RPC: Last session removed req=%p\n", req);
307 xprt_free_allocation(req);
308 return;
309 }
310}
311
312/*
313 * One or more rpc_rqst structure have been preallocated during the
314 * backchannel setup. Buffer space for the send and private XDR buffers
315 * has been preallocated as well. Use xprt_alloc_bc_request to allocate
316 * to this request. Use xprt_free_bc_request to return it.
317 *
318 * We know that we're called in soft interrupt context, grab the spin_lock
319 * since there is no need to grab the bottom half spin_lock.
320 *
321 * Return an available rpc_rqst, otherwise NULL if non are available.
322 */
323struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid)
324{
325 struct rpc_rqst *req;
326
327 spin_lock(&xprt->bc_pa_lock);
328 list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) {
329 if (req->rq_connect_cookie != xprt->connect_cookie)
330 continue;
331 if (req->rq_xid == xid)
332 goto found;
333 }
334 req = xprt_alloc_bc_request(xprt, xid);
335found:
336 spin_unlock(&xprt->bc_pa_lock);
337 return req;
338}
339
340/*
341 * Add callback request to callback list. The callback
342 * service sleeps on the sv_cb_waitq waiting for new
343 * requests. Wake it up after adding enqueing the
344 * request.
345 */
346void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
347{
348 struct rpc_xprt *xprt = req->rq_xprt;
349 struct svc_serv *bc_serv = xprt->bc_serv;
350
351 spin_lock(&xprt->bc_pa_lock);
352 list_del(&req->rq_bc_pa_list);
353 xprt_dec_alloc_count(xprt, 1);
354 spin_unlock(&xprt->bc_pa_lock);
355
356 req->rq_private_buf.len = copied;
357 set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
358
359 dprintk("RPC: add callback request to list\n");
360 spin_lock(&bc_serv->sv_cb_lock);
361 list_add(&req->rq_bc_list, &bc_serv->sv_cb_list);
362 wake_up(&bc_serv->sv_cb_waitq);
363 spin_unlock(&bc_serv->sv_cb_lock);
364}
365