529 lines · c
1// SPDX-License-Identifier: GPL-2.02/*3 * Contains the core associated with submission side polling of the SQ4 * ring, offloading submissions from the application to a kernel thread.5 */6#include <linux/kernel.h>7#include <linux/errno.h>8#include <linux/file.h>9#include <linux/mm.h>10#include <linux/slab.h>11#include <linux/audit.h>12#include <linux/security.h>13#include <linux/cpuset.h>14#include <linux/io_uring.h>15 16#include <uapi/linux/io_uring.h>17 18#include "io_uring.h"19#include "napi.h"20#include "sqpoll.h"21 22#define IORING_SQPOLL_CAP_ENTRIES_VALUE 823#define IORING_TW_CAP_ENTRIES_VALUE 824 25enum {26 IO_SQ_THREAD_SHOULD_STOP = 0,27 IO_SQ_THREAD_SHOULD_PARK,28};29 30void io_sq_thread_unpark(struct io_sq_data *sqd)31 __releases(&sqd->lock)32{33 WARN_ON_ONCE(sqd->thread == current);34 35 /*36 * Do the dance but not conditional clear_bit() because it'd race with37 * other threads incrementing park_pending and setting the bit.38 */39 clear_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);40 if (atomic_dec_return(&sqd->park_pending))41 set_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);42 mutex_unlock(&sqd->lock);43}44 45void io_sq_thread_park(struct io_sq_data *sqd)46 __acquires(&sqd->lock)47{48 WARN_ON_ONCE(data_race(sqd->thread) == current);49 50 atomic_inc(&sqd->park_pending);51 set_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);52 mutex_lock(&sqd->lock);53 if (sqd->thread)54 wake_up_process(sqd->thread);55}56 57void io_sq_thread_stop(struct io_sq_data *sqd)58{59 WARN_ON_ONCE(sqd->thread == current);60 WARN_ON_ONCE(test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state));61 62 set_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);63 mutex_lock(&sqd->lock);64 if (sqd->thread)65 wake_up_process(sqd->thread);66 mutex_unlock(&sqd->lock);67 wait_for_completion(&sqd->exited);68}69 70void io_put_sq_data(struct io_sq_data *sqd)71{72 if (refcount_dec_and_test(&sqd->refs)) {73 WARN_ON_ONCE(atomic_read(&sqd->park_pending));74 75 io_sq_thread_stop(sqd);76 kfree(sqd);77 }78}79 80static __cold void io_sqd_update_thread_idle(struct io_sq_data *sqd)81{82 struct io_ring_ctx *ctx;83 unsigned sq_thread_idle = 0;84 85 list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)86 sq_thread_idle = max(sq_thread_idle, ctx->sq_thread_idle);87 sqd->sq_thread_idle = sq_thread_idle;88}89 90void io_sq_thread_finish(struct io_ring_ctx *ctx)91{92 struct io_sq_data *sqd = ctx->sq_data;93 94 if (sqd) {95 io_sq_thread_park(sqd);96 list_del_init(&ctx->sqd_list);97 io_sqd_update_thread_idle(sqd);98 io_sq_thread_unpark(sqd);99 100 io_put_sq_data(sqd);101 ctx->sq_data = NULL;102 }103}104 105static struct io_sq_data *io_attach_sq_data(struct io_uring_params *p)106{107 struct io_ring_ctx *ctx_attach;108 struct io_sq_data *sqd;109 struct fd f;110 111 f = fdget(p->wq_fd);112 if (!fd_file(f))113 return ERR_PTR(-ENXIO);114 if (!io_is_uring_fops(fd_file(f))) {115 fdput(f);116 return ERR_PTR(-EINVAL);117 }118 119 ctx_attach = fd_file(f)->private_data;120 sqd = ctx_attach->sq_data;121 if (!sqd) {122 fdput(f);123 return ERR_PTR(-EINVAL);124 }125 if (sqd->task_tgid != current->tgid) {126 fdput(f);127 return ERR_PTR(-EPERM);128 }129 130 refcount_inc(&sqd->refs);131 fdput(f);132 return sqd;133}134 135static struct io_sq_data *io_get_sq_data(struct io_uring_params *p,136 bool *attached)137{138 struct io_sq_data *sqd;139 140 *attached = false;141 if (p->flags & IORING_SETUP_ATTACH_WQ) {142 sqd = io_attach_sq_data(p);143 if (!IS_ERR(sqd)) {144 *attached = true;145 return sqd;146 }147 /* fall through for EPERM case, setup new sqd/task */148 if (PTR_ERR(sqd) != -EPERM)149 return sqd;150 }151 152 sqd = kzalloc(sizeof(*sqd), GFP_KERNEL);153 if (!sqd)154 return ERR_PTR(-ENOMEM);155 156 atomic_set(&sqd->park_pending, 0);157 refcount_set(&sqd->refs, 1);158 INIT_LIST_HEAD(&sqd->ctx_list);159 mutex_init(&sqd->lock);160 init_waitqueue_head(&sqd->wait);161 init_completion(&sqd->exited);162 return sqd;163}164 165static inline bool io_sqd_events_pending(struct io_sq_data *sqd)166{167 return READ_ONCE(sqd->state);168}169 170static HWJS_SUSPENDS int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)171{172 unsigned int to_submit;173 int ret = 0;174 175 to_submit = io_sqring_entries(ctx);176 /* if we're handling multiple rings, cap submit size for fairness */177 if (cap_entries && to_submit > IORING_SQPOLL_CAP_ENTRIES_VALUE)178 to_submit = IORING_SQPOLL_CAP_ENTRIES_VALUE;179 180 if (to_submit || !wq_list_empty(&ctx->iopoll_list)) {181 const struct cred *creds = NULL;182 183 if (ctx->sq_creds != current_cred())184 creds = override_creds(ctx->sq_creds);185 186 mutex_lock(&ctx->uring_lock);187 if (!wq_list_empty(&ctx->iopoll_list))188 io_do_iopoll(ctx, true);189 190 /*191 * Don't submit if refs are dying, good for io_uring_register(),192 * but also it is relied upon by io_ring_exit_work()193 */194 if (to_submit && likely(!percpu_ref_is_dying(&ctx->refs)) &&195 !(ctx->flags & IORING_SETUP_R_DISABLED))196 ret = io_submit_sqes(ctx, to_submit);197 mutex_unlock(&ctx->uring_lock);198 199 if (to_submit && wq_has_sleeper(&ctx->sqo_sq_wait))200 wake_up(&ctx->sqo_sq_wait);201 if (creds)202 revert_creds(creds);203 }204 205 return ret;206}207 208static HWJS_SUSPENDS bool io_sqd_handle_event(struct io_sq_data *sqd)209{210 bool did_sig = false;211 struct ksignal ksig;212 213 if (test_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state) ||214 signal_pending(current)) {215 mutex_unlock(&sqd->lock);216 if (signal_pending(current))217 did_sig = get_signal(&ksig);218 cond_resched();219 mutex_lock(&sqd->lock);220 sqd->sq_cpu = raw_smp_processor_id();221 }222 return did_sig || test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);223}224 225/*226 * Run task_work, processing the retry_list first. The retry_list holds227 * entries that we passed on in the previous run, if we had more task_work228 * than we were asked to process. Newly queued task_work isn't run until the229 * retry list has been fully processed.230 */231static HWJS_SUSPENDS unsigned int io_sq_tw(struct llist_node **retry_list, int max_entries)232{233 struct io_uring_task *tctx = current->io_uring;234 unsigned int count = 0;235 236 if (*retry_list) {237 *retry_list = io_handle_tw_list(*retry_list, &count, max_entries);238 if (count >= max_entries)239 goto out;240 max_entries -= count;241 }242 *retry_list = tctx_task_work_run(tctx, max_entries, &count);243out:244 if (task_work_pending(current))245 task_work_run();246 return count;247}248 249static bool io_sq_tw_pending(struct llist_node *retry_list)250{251 struct io_uring_task *tctx = current->io_uring;252 253 return retry_list || !llist_empty(&tctx->task_list);254}255 256static void io_sq_update_worktime(struct io_sq_data *sqd, struct rusage *start)257{258 struct rusage end;259 260 getrusage(current, RUSAGE_SELF, &end);261 end.ru_stime.tv_sec -= start->ru_stime.tv_sec;262 end.ru_stime.tv_usec -= start->ru_stime.tv_usec;263 264 sqd->work_time += end.ru_stime.tv_usec + end.ru_stime.tv_sec * 1000000;265}266 267static HWJS_SUSPENDS int io_sq_thread(void *data)268{269 struct llist_node *retry_list = NULL;270 struct io_sq_data *sqd = data;271 struct io_ring_ctx *ctx;272 struct rusage start;273 unsigned long timeout = 0;274 char buf[TASK_COMM_LEN];275 DEFINE_WAIT(wait);276 277 /* offload context creation failed, just exit */278 if (!current->io_uring)279 goto err_out;280 281 snprintf(buf, sizeof(buf), "iou-sqp-%d", sqd->task_pid);282 set_task_comm(current, buf);283 284 /* reset to our pid after we've set task_comm, for fdinfo */285 sqd->task_pid = current->pid;286 287 if (sqd->sq_cpu != -1) {288 set_cpus_allowed_ptr(current, cpumask_of(sqd->sq_cpu));289 } else {290 set_cpus_allowed_ptr(current, cpu_online_mask);291 sqd->sq_cpu = raw_smp_processor_id();292 }293 294 /*295 * Force audit context to get setup, in case we do prep side async296 * operations that would trigger an audit call before any issue side297 * audit has been done.298 */299 audit_uring_entry(IORING_OP_NOP);300 audit_uring_exit(true, 0);301 302 mutex_lock(&sqd->lock);303 while (1) {304 bool cap_entries, sqt_spin = false;305 306 if (io_sqd_events_pending(sqd) || signal_pending(current)) {307 if (io_sqd_handle_event(sqd))308 break;309 timeout = jiffies + sqd->sq_thread_idle;310 }311 312 cap_entries = !list_is_singular(&sqd->ctx_list);313 getrusage(current, RUSAGE_SELF, &start);314 list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {315 int ret = __io_sq_thread(ctx, cap_entries);316 317 if (!sqt_spin && (ret > 0 || !wq_list_empty(&ctx->iopoll_list)))318 sqt_spin = true;319 }320 if (io_sq_tw(&retry_list, IORING_TW_CAP_ENTRIES_VALUE))321 sqt_spin = true;322 323 list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)324 if (io_napi(ctx))325 io_napi_sqpoll_busy_poll(ctx);326 327 if (sqt_spin || !time_after(jiffies, timeout)) {328 if (sqt_spin) {329 io_sq_update_worktime(sqd, &start);330 timeout = jiffies + sqd->sq_thread_idle;331 }332 if (unlikely(need_resched())) {333 mutex_unlock(&sqd->lock);334 cond_resched();335 mutex_lock(&sqd->lock);336 sqd->sq_cpu = raw_smp_processor_id();337 }338 continue;339 }340 341 prepare_to_wait(&sqd->wait, &wait, TASK_INTERRUPTIBLE);342 if (!io_sqd_events_pending(sqd) && !io_sq_tw_pending(retry_list)) {343 bool needs_sched = true;344 345 list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {346 atomic_or(IORING_SQ_NEED_WAKEUP,347 &ctx->rings->sq_flags);348 if ((ctx->flags & IORING_SETUP_IOPOLL) &&349 !wq_list_empty(&ctx->iopoll_list)) {350 needs_sched = false;351 break;352 }353 354 /*355 * Ensure the store of the wakeup flag is not356 * reordered with the load of the SQ tail357 */358 smp_mb__after_atomic();359 360 if (io_sqring_entries(ctx)) {361 needs_sched = false;362 break;363 }364 }365 366 if (needs_sched) {367 mutex_unlock(&sqd->lock);368 schedule();369 mutex_lock(&sqd->lock);370 sqd->sq_cpu = raw_smp_processor_id();371 }372 list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)373 atomic_andnot(IORING_SQ_NEED_WAKEUP,374 &ctx->rings->sq_flags);375 }376 377 finish_wait(&sqd->wait, &wait);378 timeout = jiffies + sqd->sq_thread_idle;379 }380 381 if (retry_list)382 io_sq_tw(&retry_list, UINT_MAX);383 384 io_uring_cancel_generic(true, sqd);385 sqd->thread = NULL;386 list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)387 atomic_or(IORING_SQ_NEED_WAKEUP, &ctx->rings->sq_flags);388 io_run_task_work();389 mutex_unlock(&sqd->lock);390err_out:391 complete(&sqd->exited);392 do_exit(0);393}394 395void io_sqpoll_wait_sq(struct io_ring_ctx *ctx)396{397 DEFINE_WAIT(wait);398 399 do {400 if (!io_sqring_full(ctx))401 break;402 prepare_to_wait(&ctx->sqo_sq_wait, &wait, TASK_INTERRUPTIBLE);403 404 if (!io_sqring_full(ctx))405 break;406 schedule();407 } while (!signal_pending(current));408 409 finish_wait(&ctx->sqo_sq_wait, &wait);410}411 412__cold int io_sq_offload_create(struct io_ring_ctx *ctx,413 struct io_uring_params *p)414{415 int ret;416 417 /* Retain compatibility with failing for an invalid attach attempt */418 if ((ctx->flags & (IORING_SETUP_ATTACH_WQ | IORING_SETUP_SQPOLL)) ==419 IORING_SETUP_ATTACH_WQ) {420 struct fd f;421 422 f = fdget(p->wq_fd);423 if (!fd_file(f))424 return -ENXIO;425 if (!io_is_uring_fops(fd_file(f))) {426 fdput(f);427 return -EINVAL;428 }429 fdput(f);430 }431 if (ctx->flags & IORING_SETUP_SQPOLL) {432 struct task_struct *tsk;433 struct io_sq_data *sqd;434 bool attached;435 436 ret = security_uring_sqpoll();437 if (ret)438 return ret;439 440 sqd = io_get_sq_data(p, &attached);441 if (IS_ERR(sqd)) {442 ret = PTR_ERR(sqd);443 goto err;444 }445 446 ctx->sq_creds = get_current_cred();447 ctx->sq_data = sqd;448 ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle);449 if (!ctx->sq_thread_idle)450 ctx->sq_thread_idle = HZ;451 452 io_sq_thread_park(sqd);453 list_add(&ctx->sqd_list, &sqd->ctx_list);454 io_sqd_update_thread_idle(sqd);455 /* don't attach to a dying SQPOLL thread, would be racy */456 ret = (attached && !sqd->thread) ? -ENXIO : 0;457 io_sq_thread_unpark(sqd);458 459 if (ret < 0)460 goto err;461 if (attached)462 return 0;463 464 if (p->flags & IORING_SETUP_SQ_AFF) {465 cpumask_var_t allowed_mask;466 int cpu = p->sq_thread_cpu;467 468 ret = -EINVAL;469 if (cpu >= nr_cpu_ids || !cpu_online(cpu))470 goto err_sqpoll;471 ret = -ENOMEM;472 if (!alloc_cpumask_var(&allowed_mask, GFP_KERNEL))473 goto err_sqpoll;474 ret = -EINVAL;475 cpuset_cpus_allowed(current, allowed_mask);476 if (!cpumask_test_cpu(cpu, allowed_mask)) {477 free_cpumask_var(allowed_mask);478 goto err_sqpoll;479 }480 free_cpumask_var(allowed_mask);481 sqd->sq_cpu = cpu;482 } else {483 sqd->sq_cpu = -1;484 }485 486 sqd->task_pid = current->pid;487 sqd->task_tgid = current->tgid;488 tsk = create_io_thread(io_sq_thread, sqd, NUMA_NO_NODE);489 if (IS_ERR(tsk)) {490 ret = PTR_ERR(tsk);491 goto err_sqpoll;492 }493 494 sqd->thread = tsk;495 ret = io_uring_alloc_task_context(tsk, ctx);496 wake_up_new_task(tsk);497 if (ret)498 goto err;499 } else if (p->flags & IORING_SETUP_SQ_AFF) {500 /* Can't have SQ_AFF without SQPOLL */501 ret = -EINVAL;502 goto err;503 }504 505 return 0;506err_sqpoll:507 complete(&ctx->sq_data->exited);508err:509 io_sq_thread_finish(ctx);510 return ret;511}512 513__cold int io_sqpoll_wq_cpu_affinity(struct io_ring_ctx *ctx,514 cpumask_var_t mask)515{516 struct io_sq_data *sqd = ctx->sq_data;517 int ret = -EINVAL;518 519 if (sqd) {520 io_sq_thread_park(sqd);521 /* Don't set affinity for a dying thread */522 if (sqd->thread)523 ret = io_wq_cpu_affinity(sqd->thread->io_uring, mask);524 io_sq_thread_unpark(sqd);525 }526 527 return ret;528}529