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1// SPDX-License-Identifier: GPL-2.0-only
2/******************************************************************************
3
4(c) 2007 Network Appliance, Inc. All Rights Reserved.
5(c) 2009 NetApp. All Rights Reserved.
6
7
8******************************************************************************/
9
10#include <linux/tcp.h>
11#include <linux/slab.h>
12#include <linux/sunrpc/xprt.h>
13#include <linux/export.h>
14#include <linux/sunrpc/bc_xprt.h>
15
16#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
17#define RPCDBG_FACILITY RPCDBG_TRANS
18#endif
19
20#define BC_MAX_SLOTS 64U
21
22unsigned int xprt_bc_max_slots(struct rpc_xprt *xprt)
23{
24 return BC_MAX_SLOTS;
25}
26
27/*
28 * Helper routines that track the number of preallocation elements
29 * on the transport.
30 */
31static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
32{
33 return xprt->bc_alloc_count < xprt->bc_alloc_max;
34}
35
36/*
37 * Free the preallocated rpc_rqst structure and the memory
38 * buffers hanging off of it.
39 */
40static void xprt_free_allocation(struct rpc_rqst *req)
41{
42 struct xdr_buf *xbufp;
43
44 dprintk("RPC: free allocations for req= %p\n", req);
45 WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
46 xbufp = &req->rq_rcv_buf;
47 free_page((unsigned long)xbufp->head[0].iov_base);
48 xbufp = &req->rq_snd_buf;
49 free_page((unsigned long)xbufp->head[0].iov_base);
50 kfree(req);
51}
52
53static void xprt_bc_reinit_xdr_buf(struct xdr_buf *buf)
54{
55 buf->head[0].iov_len = PAGE_SIZE;
56 buf->tail[0].iov_len = 0;
57 buf->pages = NULL;
58 buf->page_len = 0;
59 buf->flags = 0;
60 buf->len = 0;
61 buf->buflen = PAGE_SIZE;
62}
63
64static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags)
65{
66 struct page *page;
67 /* Preallocate one XDR receive buffer */
68 page = alloc_page(gfp_flags);
69 if (page == NULL)
70 return -ENOMEM;
71 xdr_buf_init(buf, page_address(page), PAGE_SIZE);
72 return 0;
73}
74
75static struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt)
76{
77 gfp_t gfp_flags = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
78 struct rpc_rqst *req;
79
80 /* Pre-allocate one backchannel rpc_rqst */
81 req = kzalloc(sizeof(*req), gfp_flags);
82 if (req == NULL)
83 return NULL;
84
85 req->rq_xprt = xprt;
86
87 /* Preallocate one XDR receive buffer */
88 if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) {
89 printk(KERN_ERR "Failed to create bc receive xbuf\n");
90 goto out_free;
91 }
92 req->rq_rcv_buf.len = PAGE_SIZE;
93
94 /* Preallocate one XDR send buffer */
95 if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) {
96 printk(KERN_ERR "Failed to create bc snd xbuf\n");
97 goto out_free;
98 }
99 return req;
100out_free:
101 xprt_free_allocation(req);
102 return NULL;
103}
104
105/*
106 * Preallocate up to min_reqs structures and related buffers for use
107 * by the backchannel. This function can be called multiple times
108 * when creating new sessions that use the same rpc_xprt. The
109 * preallocated buffers are added to the pool of resources used by
110 * the rpc_xprt. Any one of these resources may be used by an
111 * incoming callback request. It's up to the higher levels in the
112 * stack to enforce that the maximum number of session slots is not
113 * being exceeded.
114 *
115 * Some callback arguments can be large. For example, a pNFS server
116 * using multiple deviceids. The list can be unbound, but the client
117 * has the ability to tell the server the maximum size of the callback
118 * requests. Each deviceID is 16 bytes, so allocate one page
119 * for the arguments to have enough room to receive a number of these
120 * deviceIDs. The NFS client indicates to the pNFS server that its
121 * callback requests can be up to 4096 bytes in size.
122 */
123int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs)
124{
125 if (!xprt->ops->bc_setup)
126 return 0;
127 return xprt->ops->bc_setup(xprt, min_reqs);
128}
129EXPORT_SYMBOL_GPL(xprt_setup_backchannel);
130
131int xprt_setup_bc(struct rpc_xprt *xprt, unsigned int min_reqs)
132{
133 struct rpc_rqst *req;
134 struct list_head tmp_list;
135 int i;
136
137 dprintk("RPC: setup backchannel transport\n");
138
139 if (min_reqs > BC_MAX_SLOTS)
140 min_reqs = BC_MAX_SLOTS;
141
142 /*
143 * We use a temporary list to keep track of the preallocated
144 * buffers. Once we're done building the list we splice it
145 * into the backchannel preallocation list off of the rpc_xprt
146 * struct. This helps minimize the amount of time the list
147 * lock is held on the rpc_xprt struct. It also makes cleanup
148 * easier in case of memory allocation errors.
149 */
150 INIT_LIST_HEAD(&tmp_list);
151 for (i = 0; i < min_reqs; i++) {
152 /* Pre-allocate one backchannel rpc_rqst */
153 req = xprt_alloc_bc_req(xprt);
154 if (req == NULL) {
155 printk(KERN_ERR "Failed to create bc rpc_rqst\n");
156 goto out_free;
157 }
158
159 /* Add the allocated buffer to the tmp list */
160 dprintk("RPC: adding req= %p\n", req);
161 list_add(&req->rq_bc_pa_list, &tmp_list);
162 }
163
164 /*
165 * Add the temporary list to the backchannel preallocation list
166 */
167 spin_lock(&xprt->bc_pa_lock);
168 list_splice(&tmp_list, &xprt->bc_pa_list);
169 xprt->bc_alloc_count += min_reqs;
170 xprt->bc_alloc_max += min_reqs;
171 atomic_add(min_reqs, &xprt->bc_slot_count);
172 spin_unlock(&xprt->bc_pa_lock);
173
174 dprintk("RPC: setup backchannel transport done\n");
175 return 0;
176
177out_free:
178 /*
179 * Memory allocation failed, free the temporary list
180 */
181 while (!list_empty(&tmp_list)) {
182 req = list_first_entry(&tmp_list,
183 struct rpc_rqst,
184 rq_bc_pa_list);
185 list_del(&req->rq_bc_pa_list);
186 xprt_free_allocation(req);
187 }
188
189 dprintk("RPC: setup backchannel transport failed\n");
190 return -ENOMEM;
191}
192
193/**
194 * xprt_destroy_backchannel - Destroys the backchannel preallocated structures.
195 * @xprt: the transport holding the preallocated strucures
196 * @max_reqs: the maximum number of preallocated structures to destroy
197 *
198 * Since these structures may have been allocated by multiple calls
199 * to xprt_setup_backchannel, we only destroy up to the maximum number
200 * of reqs specified by the caller.
201 */
202void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
203{
204 if (xprt->ops->bc_destroy)
205 xprt->ops->bc_destroy(xprt, max_reqs);
206}
207EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);
208
209void xprt_destroy_bc(struct rpc_xprt *xprt, unsigned int max_reqs)
210{
211 struct rpc_rqst *req = NULL, *tmp = NULL;
212
213 dprintk("RPC: destroy backchannel transport\n");
214
215 if (max_reqs == 0)
216 goto out;
217
218 spin_lock_bh(&xprt->bc_pa_lock);
219 xprt->bc_alloc_max -= min(max_reqs, xprt->bc_alloc_max);
220 list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
221 dprintk("RPC: req=%p\n", req);
222 list_del(&req->rq_bc_pa_list);
223 xprt_free_allocation(req);
224 xprt->bc_alloc_count--;
225 atomic_dec(&xprt->bc_slot_count);
226 if (--max_reqs == 0)
227 break;
228 }
229 spin_unlock_bh(&xprt->bc_pa_lock);
230
231out:
232 dprintk("RPC: backchannel list empty= %s\n",
233 list_empty(&xprt->bc_pa_list) ? "true" : "false");
234}
235
236static struct rpc_rqst *xprt_get_bc_request(struct rpc_xprt *xprt, __be32 xid,
237 struct rpc_rqst *new)
238{
239 struct rpc_rqst *req = NULL;
240
241 dprintk("RPC: allocate a backchannel request\n");
242 if (list_empty(&xprt->bc_pa_list)) {
243 if (!new)
244 goto not_found;
245 if (atomic_read(&xprt->bc_slot_count) >= BC_MAX_SLOTS)
246 goto not_found;
247 list_add_tail(&new->rq_bc_pa_list, &xprt->bc_pa_list);
248 xprt->bc_alloc_count++;
249 atomic_inc(&xprt->bc_slot_count);
250 }
251 req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
252 rq_bc_pa_list);
253 req->rq_reply_bytes_recvd = 0;
254 memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
255 sizeof(req->rq_private_buf));
256 req->rq_xid = xid;
257 req->rq_connect_cookie = xprt->connect_cookie;
258 dprintk("RPC: backchannel req=%p\n", req);
259not_found:
260 return req;
261}
262
263/*
264 * Return the preallocated rpc_rqst structure and XDR buffers
265 * associated with this rpc_task.
266 */
267void xprt_free_bc_request(struct rpc_rqst *req)
268{
269 struct rpc_xprt *xprt = req->rq_xprt;
270
271 xprt->ops->bc_free_rqst(req);
272}
273
274void xprt_free_bc_rqst(struct rpc_rqst *req)
275{
276 struct rpc_xprt *xprt = req->rq_xprt;
277
278 dprintk("RPC: free backchannel req=%p\n", req);
279
280 req->rq_connect_cookie = xprt->connect_cookie - 1;
281 smp_mb__before_atomic();
282 clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
283 smp_mb__after_atomic();
284
285 /*
286 * Return it to the list of preallocations so that it
287 * may be reused by a new callback request.
288 */
289 spin_lock_bh(&xprt->bc_pa_lock);
290 if (xprt_need_to_requeue(xprt)) {
291 xprt_bc_reinit_xdr_buf(&req->rq_snd_buf);
292 xprt_bc_reinit_xdr_buf(&req->rq_rcv_buf);
293 req->rq_rcv_buf.len = PAGE_SIZE;
294 list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
295 xprt->bc_alloc_count++;
296 atomic_inc(&xprt->bc_slot_count);
297 req = NULL;
298 }
299 spin_unlock_bh(&xprt->bc_pa_lock);
300 if (req != NULL) {
301 /*
302 * The last remaining session was destroyed while this
303 * entry was in use. Free the entry and don't attempt
304 * to add back to the list because there is no need to
305 * have anymore preallocated entries.
306 */
307 dprintk("RPC: Last session removed req=%p\n", req);
308 xprt_free_allocation(req);
309 }
310 xprt_put(xprt);
311}
312
313/*
314 * One or more rpc_rqst structure have been preallocated during the
315 * backchannel setup. Buffer space for the send and private XDR buffers
316 * has been preallocated as well. Use xprt_alloc_bc_request to allocate
317 * to this request. Use xprt_free_bc_request to return it.
318 *
319 * We know that we're called in soft interrupt context, grab the spin_lock
320 * since there is no need to grab the bottom half spin_lock.
321 *
322 * Return an available rpc_rqst, otherwise NULL if non are available.
323 */
324struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid)
325{
326 struct rpc_rqst *req, *new = NULL;
327
328 do {
329 spin_lock(&xprt->bc_pa_lock);
330 list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) {
331 if (req->rq_connect_cookie != xprt->connect_cookie)
332 continue;
333 if (req->rq_xid == xid)
334 goto found;
335 }
336 req = xprt_get_bc_request(xprt, xid, new);
337found:
338 spin_unlock(&xprt->bc_pa_lock);
339 if (new) {
340 if (req != new)
341 xprt_free_allocation(new);
342 break;
343 } else if (req)
344 break;
345 new = xprt_alloc_bc_req(xprt);
346 } while (new);
347 return req;
348}
349
350/*
351 * Add callback request to callback list. Wake a thread
352 * on the first pool (usually the only pool) to handle it.
353 */
354void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
355{
356 struct rpc_xprt *xprt = req->rq_xprt;
357 struct svc_serv *bc_serv = xprt->bc_serv;
358
359 spin_lock(&xprt->bc_pa_lock);
360 list_del(&req->rq_bc_pa_list);
361 xprt->bc_alloc_count--;
362 spin_unlock(&xprt->bc_pa_lock);
363
364 req->rq_private_buf.len = copied;
365 set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
366
367 dprintk("RPC: add callback request to list\n");
368 xprt_get(xprt);
369 lwq_enqueue(&req->rq_bc_list, &bc_serv->sv_cb_list);
370 svc_pool_wake_idle_thread(&bc_serv->sv_pools[0]);
371}
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_bh(&xprt->bc_pa_lock);
175 list_splice(&tmp_list, &xprt->bc_pa_list);
176 xprt_inc_alloc_count(xprt, min_reqs);
177 spin_unlock_bh(&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