1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/kernel.h> 3 #include <linux/errno.h> 4 #include <linux/fs.h> 5 #include <linux/file.h> 6 #include <linux/io_uring.h> 7 8 #include <uapi/linux/io_uring.h> 9 10 #include "../kernel/futex/futex.h" 11 #include "io_uring.h" 12 #include "alloc_cache.h" 13 #include "futex.h" 14 15 struct io_futex { 16 struct file *file; 17 void __user *uaddr; 18 unsigned long futex_val; 19 unsigned long futex_mask; 20 unsigned long futexv_owned; 21 u32 futex_flags; 22 unsigned int futex_nr; 23 bool futexv_unqueued; 24 }; 25 26 struct io_futex_data { 27 struct futex_q q; 28 struct io_kiocb *req; 29 }; 30 31 #define IO_FUTEX_ALLOC_CACHE_MAX 32 32 33 bool io_futex_cache_init(struct io_ring_ctx *ctx) 34 { 35 return io_alloc_cache_init(&ctx->futex_cache, IO_FUTEX_ALLOC_CACHE_MAX, 36 sizeof(struct io_futex_data), 0); 37 } 38 39 void io_futex_cache_free(struct io_ring_ctx *ctx) 40 { 41 io_alloc_cache_free(&ctx->futex_cache, kfree); 42 } 43 44 static void __io_futex_complete(struct io_kiocb *req, io_tw_token_t tw) 45 { 46 hlist_del_init(&req->hash_node); 47 io_req_task_complete(req, tw); 48 } 49 50 static void io_futex_complete(struct io_kiocb *req, io_tw_token_t tw) 51 { 52 struct io_ring_ctx *ctx = req->ctx; 53 54 io_tw_lock(ctx, tw); 55 io_cache_free(&ctx->futex_cache, req->async_data); 56 io_req_async_data_clear(req, 0); 57 __io_futex_complete(req, tw); 58 } 59 60 static void io_futexv_complete(struct io_kiocb *req, io_tw_token_t tw) 61 { 62 struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); 63 struct futex_vector *futexv = req->async_data; 64 65 io_tw_lock(req->ctx, tw); 66 67 if (!iof->futexv_unqueued) { 68 int res; 69 70 res = futex_unqueue_multiple(futexv, iof->futex_nr); 71 if (res != -1) 72 io_req_set_res(req, res, 0); 73 } 74 75 io_req_async_data_free(req); 76 __io_futex_complete(req, tw); 77 } 78 79 static bool io_futexv_claim(struct io_futex *iof) 80 { 81 if (test_bit(0, &iof->futexv_owned) || 82 test_and_set_bit_lock(0, &iof->futexv_owned)) 83 return false; 84 return true; 85 } 86 87 static bool __io_futex_cancel(struct io_kiocb *req) 88 { 89 /* futex wake already done or in progress */ 90 if (req->opcode == IORING_OP_FUTEX_WAIT) { 91 struct io_futex_data *ifd = req->async_data; 92 93 if (!futex_unqueue(&ifd->q)) 94 return false; 95 req->io_task_work.func = io_futex_complete; 96 } else { 97 struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); 98 99 if (!io_futexv_claim(iof)) 100 return false; 101 req->io_task_work.func = io_futexv_complete; 102 } 103 104 hlist_del_init(&req->hash_node); 105 io_req_set_res(req, -ECANCELED, 0); 106 io_req_task_work_add(req); 107 return true; 108 } 109 110 int io_futex_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd, 111 unsigned int issue_flags) 112 { 113 return io_cancel_remove(ctx, cd, issue_flags, &ctx->futex_list, __io_futex_cancel); 114 } 115 116 bool io_futex_remove_all(struct io_ring_ctx *ctx, struct io_uring_task *tctx, 117 bool cancel_all) 118 { 119 return io_cancel_remove_all(ctx, tctx, &ctx->futex_list, cancel_all, __io_futex_cancel); 120 } 121 122 int io_futex_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) 123 { 124 struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); 125 u32 flags; 126 127 if (unlikely(sqe->len || sqe->futex_flags || sqe->buf_index || 128 sqe->file_index)) 129 return -EINVAL; 130 131 iof->uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr)); 132 iof->futex_val = READ_ONCE(sqe->addr2); 133 iof->futex_mask = READ_ONCE(sqe->addr3); 134 flags = READ_ONCE(sqe->fd); 135 136 if (flags & ~FUTEX2_VALID_MASK) 137 return -EINVAL; 138 139 iof->futex_flags = futex2_to_flags(flags); 140 if (!futex_flags_valid(iof->futex_flags)) 141 return -EINVAL; 142 143 if (!futex_validate_input(iof->futex_flags, iof->futex_val) || 144 !futex_validate_input(iof->futex_flags, iof->futex_mask)) 145 return -EINVAL; 146 147 /* Mark as inflight, so file exit cancelation will find it */ 148 io_req_track_inflight(req); 149 return 0; 150 } 151 152 static void io_futex_wakev_fn(struct wake_q_head *wake_q, struct futex_q *q) 153 { 154 struct io_kiocb *req = q->wake_data; 155 struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); 156 157 if (!io_futexv_claim(iof)) 158 return; 159 if (unlikely(!__futex_wake_mark(q))) 160 return; 161 162 io_req_set_res(req, 0, 0); 163 req->io_task_work.func = io_futexv_complete; 164 io_req_task_work_add(req); 165 } 166 167 int io_futexv_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) 168 { 169 struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); 170 struct futex_vector *futexv; 171 int ret; 172 173 /* No flags or mask supported for waitv */ 174 if (unlikely(sqe->fd || sqe->buf_index || sqe->file_index || 175 sqe->addr2 || sqe->futex_flags || sqe->addr3)) 176 return -EINVAL; 177 178 iof->uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr)); 179 iof->futex_nr = READ_ONCE(sqe->len); 180 if (!iof->futex_nr || iof->futex_nr > FUTEX_WAITV_MAX) 181 return -EINVAL; 182 183 futexv = kcalloc(iof->futex_nr, sizeof(*futexv), GFP_KERNEL); 184 if (!futexv) 185 return -ENOMEM; 186 187 ret = futex_parse_waitv(futexv, iof->uaddr, iof->futex_nr, 188 io_futex_wakev_fn, req); 189 if (ret) { 190 kfree(futexv); 191 return ret; 192 } 193 194 /* Mark as inflight, so file exit cancelation will find it */ 195 io_req_track_inflight(req); 196 iof->futexv_owned = 0; 197 iof->futexv_unqueued = 0; 198 req->flags |= REQ_F_ASYNC_DATA; 199 req->async_data = futexv; 200 return 0; 201 } 202 203 static void io_futex_wake_fn(struct wake_q_head *wake_q, struct futex_q *q) 204 { 205 struct io_futex_data *ifd = container_of(q, struct io_futex_data, q); 206 struct io_kiocb *req = ifd->req; 207 208 if (unlikely(!__futex_wake_mark(q))) 209 return; 210 211 io_req_set_res(req, 0, 0); 212 req->io_task_work.func = io_futex_complete; 213 io_req_task_work_add(req); 214 } 215 216 int io_futexv_wait(struct io_kiocb *req, unsigned int issue_flags) 217 { 218 struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); 219 struct futex_vector *futexv = req->async_data; 220 struct io_ring_ctx *ctx = req->ctx; 221 int ret, woken = -1; 222 223 io_ring_submit_lock(ctx, issue_flags); 224 225 ret = futex_wait_multiple_setup(futexv, iof->futex_nr, &woken); 226 227 /* 228 * Error case, ret is < 0. Mark the request as failed. 229 */ 230 if (unlikely(ret < 0)) { 231 io_ring_submit_unlock(ctx, issue_flags); 232 req_set_fail(req); 233 io_req_set_res(req, ret, 0); 234 io_req_async_data_free(req); 235 return IOU_COMPLETE; 236 } 237 238 /* 239 * 0 return means that we successfully setup the waiters, and that 240 * nobody triggered a wakeup while we were doing so. If the wakeup 241 * happened post setup, the task_work will be run post this issue and 242 * under the submission lock. 1 means We got woken while setting up, 243 * let that side do the completion. Note that 244 * futex_wait_multiple_setup() will have unqueued all the futexes in 245 * this case. Mark us as having done that already, since this is 246 * different from normal wakeup. 247 */ 248 if (!ret) { 249 /* 250 * If futex_wait_multiple_setup() returns 0 for a 251 * successful setup, then the task state will not be 252 * runnable. This is fine for the sync syscall, as 253 * it'll be blocking unless we already got one of the 254 * futexes woken, but it obviously won't work for an 255 * async invocation. Mark us runnable again. 256 */ 257 __set_current_state(TASK_RUNNING); 258 hlist_add_head(&req->hash_node, &ctx->futex_list); 259 } else { 260 iof->futexv_unqueued = 1; 261 if (woken != -1) 262 io_req_set_res(req, woken, 0); 263 } 264 265 io_ring_submit_unlock(ctx, issue_flags); 266 return IOU_ISSUE_SKIP_COMPLETE; 267 } 268 269 int io_futex_wait(struct io_kiocb *req, unsigned int issue_flags) 270 { 271 struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); 272 struct io_ring_ctx *ctx = req->ctx; 273 struct io_futex_data *ifd = NULL; 274 int ret; 275 276 if (!iof->futex_mask) { 277 ret = -EINVAL; 278 goto done; 279 } 280 281 io_ring_submit_lock(ctx, issue_flags); 282 ifd = io_cache_alloc(&ctx->futex_cache, GFP_NOWAIT); 283 if (!ifd) { 284 ret = -ENOMEM; 285 goto done_unlock; 286 } 287 288 req->flags |= REQ_F_ASYNC_DATA; 289 req->async_data = ifd; 290 ifd->q = futex_q_init; 291 ifd->q.bitset = iof->futex_mask; 292 ifd->q.wake = io_futex_wake_fn; 293 ifd->req = req; 294 295 ret = futex_wait_setup(iof->uaddr, iof->futex_val, iof->futex_flags, 296 &ifd->q, NULL, NULL); 297 if (!ret) { 298 hlist_add_head(&req->hash_node, &ctx->futex_list); 299 io_ring_submit_unlock(ctx, issue_flags); 300 301 return IOU_ISSUE_SKIP_COMPLETE; 302 } 303 304 done_unlock: 305 io_ring_submit_unlock(ctx, issue_flags); 306 done: 307 if (ret < 0) 308 req_set_fail(req); 309 io_req_set_res(req, ret, 0); 310 io_req_async_data_free(req); 311 return IOU_COMPLETE; 312 } 313 314 int io_futex_wake(struct io_kiocb *req, unsigned int issue_flags) 315 { 316 struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); 317 int ret; 318 319 /* 320 * Strict flags - ensure that waking 0 futexes yields a 0 result. 321 * See commit 43adf8449510 ("futex: FLAGS_STRICT") for details. 322 */ 323 ret = futex_wake(iof->uaddr, FLAGS_STRICT | iof->futex_flags, 324 iof->futex_val, iof->futex_mask); 325 if (ret < 0) 326 req_set_fail(req); 327 io_req_set_res(req, ret, 0); 328 return IOU_COMPLETE; 329 } 330