1 /****************************************************************************** 2 3 (c) 2007 Network Appliance, Inc. All Rights Reserved. 4 (c) 2009 NetApp. All Rights Reserved. 5 6 NetApp provides this source code under the GPL v2 License. 7 The GPL v2 license is available at 8 http://opensource.org/licenses/gpl-license.php. 9 10 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 11 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 12 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 13 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 14 CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 15 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 16 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 17 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 18 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 19 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 20 SOFTWARE, 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 */ 38 static 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 43 static 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 49 static 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 */ 59 static 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 72 static 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 83 static 84 struct 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_bc_list); 95 96 /* Preallocate one XDR receive buffer */ 97 if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) { 98 printk(KERN_ERR "Failed to create bc receive xbuf\n"); 99 goto out_free; 100 } 101 req->rq_rcv_buf.len = PAGE_SIZE; 102 103 /* Preallocate one XDR send buffer */ 104 if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) { 105 printk(KERN_ERR "Failed to create bc snd xbuf\n"); 106 goto out_free; 107 } 108 return req; 109 out_free: 110 xprt_free_allocation(req); 111 return NULL; 112 } 113 114 /* 115 * Preallocate up to min_reqs structures and related buffers for use 116 * by the backchannel. This function can be called multiple times 117 * when creating new sessions that use the same rpc_xprt. The 118 * preallocated buffers are added to the pool of resources used by 119 * the rpc_xprt. Anyone of these resources may be used used by an 120 * incoming callback request. It's up to the higher levels in the 121 * stack to enforce that the maximum number of session slots is not 122 * being exceeded. 123 * 124 * Some callback arguments can be large. For example, a pNFS server 125 * using multiple deviceids. The list can be unbound, but the client 126 * has the ability to tell the server the maximum size of the callback 127 * requests. Each deviceID is 16 bytes, so allocate one page 128 * for the arguments to have enough room to receive a number of these 129 * deviceIDs. The NFS client indicates to the pNFS server that its 130 * callback requests can be up to 4096 bytes in size. 131 */ 132 int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs) 133 { 134 if (!xprt->ops->bc_setup) 135 return 0; 136 return xprt->ops->bc_setup(xprt, min_reqs); 137 } 138 EXPORT_SYMBOL_GPL(xprt_setup_backchannel); 139 140 int xprt_setup_bc(struct rpc_xprt *xprt, unsigned int min_reqs) 141 { 142 struct rpc_rqst *req; 143 struct list_head tmp_list; 144 int i; 145 146 dprintk("RPC: setup backchannel transport\n"); 147 148 /* 149 * We use a temporary list to keep track of the preallocated 150 * buffers. Once we're done building the list we splice it 151 * into the backchannel preallocation list off of the rpc_xprt 152 * struct. This helps minimize the amount of time the list 153 * lock is held on the rpc_xprt struct. It also makes cleanup 154 * easier in case of memory allocation errors. 155 */ 156 INIT_LIST_HEAD(&tmp_list); 157 for (i = 0; i < min_reqs; i++) { 158 /* Pre-allocate one backchannel rpc_rqst */ 159 req = xprt_alloc_bc_req(xprt, GFP_KERNEL); 160 if (req == NULL) { 161 printk(KERN_ERR "Failed to create bc rpc_rqst\n"); 162 goto out_free; 163 } 164 165 /* Add the allocated buffer to the tmp list */ 166 dprintk("RPC: adding req= %p\n", req); 167 list_add(&req->rq_bc_pa_list, &tmp_list); 168 } 169 170 /* 171 * Add the temporary list to the backchannel preallocation list 172 */ 173 spin_lock(&xprt->bc_pa_lock); 174 list_splice(&tmp_list, &xprt->bc_pa_list); 175 xprt_inc_alloc_count(xprt, min_reqs); 176 spin_unlock(&xprt->bc_pa_lock); 177 178 dprintk("RPC: setup backchannel transport done\n"); 179 return 0; 180 181 out_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 */ 206 void 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 } 211 EXPORT_SYMBOL_GPL(xprt_destroy_backchannel); 212 213 void 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_dec_alloc_count(xprt, max_reqs); 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 if (--max_reqs == 0) 229 break; 230 } 231 spin_unlock_bh(&xprt->bc_pa_lock); 232 233 out: 234 dprintk("RPC: backchannel list empty= %s\n", 235 list_empty(&xprt->bc_pa_list) ? "true" : "false"); 236 } 237 238 static struct rpc_rqst *xprt_get_bc_request(struct rpc_xprt *xprt, __be32 xid, 239 struct rpc_rqst *new) 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 if (!new) 248 goto not_found; 249 list_add_tail(&new->rq_bc_pa_list, &xprt->bc_pa_list); 250 xprt->bc_alloc_count++; 251 } 252 req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst, 253 rq_bc_pa_list); 254 req->rq_reply_bytes_recvd = 0; 255 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, 256 sizeof(req->rq_private_buf)); 257 req->rq_xid = xid; 258 req->rq_connect_cookie = xprt->connect_cookie; 259 dprintk("RPC: backchannel req=%p\n", req); 260 not_found: 261 return req; 262 } 263 264 /* 265 * Return the preallocated rpc_rqst structure and XDR buffers 266 * associated with this rpc_task. 267 */ 268 void xprt_free_bc_request(struct rpc_rqst *req) 269 { 270 struct rpc_xprt *xprt = req->rq_xprt; 271 272 xprt->ops->bc_free_rqst(req); 273 } 274 275 void xprt_free_bc_rqst(struct rpc_rqst *req) 276 { 277 struct rpc_xprt *xprt = req->rq_xprt; 278 279 dprintk("RPC: free backchannel req=%p\n", req); 280 281 req->rq_connect_cookie = xprt->connect_cookie - 1; 282 smp_mb__before_atomic(); 283 clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); 284 smp_mb__after_atomic(); 285 286 /* 287 * Return it to the list of preallocations so that it 288 * may be reused by a new callback request. 289 */ 290 spin_lock_bh(&xprt->bc_pa_lock); 291 if (xprt_need_to_requeue(xprt)) { 292 list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list); 293 xprt->bc_alloc_count++; 294 req = NULL; 295 } 296 spin_unlock_bh(&xprt->bc_pa_lock); 297 if (req != NULL) { 298 /* 299 * The last remaining session was destroyed while this 300 * entry was in use. Free the entry and don't attempt 301 * to add back to the list because there is no need to 302 * have anymore preallocated entries. 303 */ 304 dprintk("RPC: Last session removed req=%p\n", req); 305 xprt_free_allocation(req); 306 return; 307 } 308 } 309 310 /* 311 * One or more rpc_rqst structure have been preallocated during the 312 * backchannel setup. Buffer space for the send and private XDR buffers 313 * has been preallocated as well. Use xprt_alloc_bc_request to allocate 314 * to this request. Use xprt_free_bc_request to return it. 315 * 316 * We know that we're called in soft interrupt context, grab the spin_lock 317 * since there is no need to grab the bottom half spin_lock. 318 * 319 * Return an available rpc_rqst, otherwise NULL if non are available. 320 */ 321 struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid) 322 { 323 struct rpc_rqst *req, *new = NULL; 324 325 do { 326 spin_lock(&xprt->bc_pa_lock); 327 list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) { 328 if (req->rq_connect_cookie != xprt->connect_cookie) 329 continue; 330 if (req->rq_xid == xid) 331 goto found; 332 } 333 req = xprt_get_bc_request(xprt, xid, new); 334 found: 335 spin_unlock(&xprt->bc_pa_lock); 336 if (new) { 337 if (req != new) 338 xprt_free_bc_rqst(new); 339 break; 340 } else if (req) 341 break; 342 new = xprt_alloc_bc_req(xprt, GFP_KERNEL); 343 } while (new); 344 return req; 345 } 346 347 /* 348 * Add callback request to callback list. The callback 349 * service sleeps on the sv_cb_waitq waiting for new 350 * requests. Wake it up after adding enqueing the 351 * request. 352 */ 353 void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied) 354 { 355 struct rpc_xprt *xprt = req->rq_xprt; 356 struct svc_serv *bc_serv = xprt->bc_serv; 357 358 spin_lock(&xprt->bc_pa_lock); 359 list_del(&req->rq_bc_pa_list); 360 xprt_dec_alloc_count(xprt, 1); 361 spin_unlock(&xprt->bc_pa_lock); 362 363 req->rq_private_buf.len = copied; 364 set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); 365 366 dprintk("RPC: add callback request to list\n"); 367 spin_lock(&bc_serv->sv_cb_lock); 368 list_add(&req->rq_bc_list, &bc_serv->sv_cb_list); 369 wake_up(&bc_serv->sv_cb_waitq); 370 spin_unlock(&bc_serv->sv_cb_lock); 371 } 372