]> Git Repo - J-linux.git/blob - io_uring/sqpoll.c
Merge patch series "riscv: Extension parsing fixes"
[J-linux.git] / io_uring / sqpoll.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Contains the core associated with submission side polling of the SQ
4  * 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/io_uring.h>
14
15 #include <uapi/linux/io_uring.h>
16
17 #include "io_uring.h"
18 #include "napi.h"
19 #include "sqpoll.h"
20
21 #define IORING_SQPOLL_CAP_ENTRIES_VALUE 8
22 #define IORING_TW_CAP_ENTRIES_VALUE     8
23
24 enum {
25         IO_SQ_THREAD_SHOULD_STOP = 0,
26         IO_SQ_THREAD_SHOULD_PARK,
27 };
28
29 void io_sq_thread_unpark(struct io_sq_data *sqd)
30         __releases(&sqd->lock)
31 {
32         WARN_ON_ONCE(sqd->thread == current);
33
34         /*
35          * Do the dance but not conditional clear_bit() because it'd race with
36          * other threads incrementing park_pending and setting the bit.
37          */
38         clear_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);
39         if (atomic_dec_return(&sqd->park_pending))
40                 set_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);
41         mutex_unlock(&sqd->lock);
42 }
43
44 void io_sq_thread_park(struct io_sq_data *sqd)
45         __acquires(&sqd->lock)
46 {
47         WARN_ON_ONCE(sqd->thread == current);
48
49         atomic_inc(&sqd->park_pending);
50         set_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);
51         mutex_lock(&sqd->lock);
52         if (sqd->thread)
53                 wake_up_process(sqd->thread);
54 }
55
56 void io_sq_thread_stop(struct io_sq_data *sqd)
57 {
58         WARN_ON_ONCE(sqd->thread == current);
59         WARN_ON_ONCE(test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state));
60
61         set_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);
62         mutex_lock(&sqd->lock);
63         if (sqd->thread)
64                 wake_up_process(sqd->thread);
65         mutex_unlock(&sqd->lock);
66         wait_for_completion(&sqd->exited);
67 }
68
69 void io_put_sq_data(struct io_sq_data *sqd)
70 {
71         if (refcount_dec_and_test(&sqd->refs)) {
72                 WARN_ON_ONCE(atomic_read(&sqd->park_pending));
73
74                 io_sq_thread_stop(sqd);
75                 kfree(sqd);
76         }
77 }
78
79 static __cold void io_sqd_update_thread_idle(struct io_sq_data *sqd)
80 {
81         struct io_ring_ctx *ctx;
82         unsigned sq_thread_idle = 0;
83
84         list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
85                 sq_thread_idle = max(sq_thread_idle, ctx->sq_thread_idle);
86         sqd->sq_thread_idle = sq_thread_idle;
87 }
88
89 void io_sq_thread_finish(struct io_ring_ctx *ctx)
90 {
91         struct io_sq_data *sqd = ctx->sq_data;
92
93         if (sqd) {
94                 io_sq_thread_park(sqd);
95                 list_del_init(&ctx->sqd_list);
96                 io_sqd_update_thread_idle(sqd);
97                 io_sq_thread_unpark(sqd);
98
99                 io_put_sq_data(sqd);
100                 ctx->sq_data = NULL;
101         }
102 }
103
104 static struct io_sq_data *io_attach_sq_data(struct io_uring_params *p)
105 {
106         struct io_ring_ctx *ctx_attach;
107         struct io_sq_data *sqd;
108         struct fd f;
109
110         f = fdget(p->wq_fd);
111         if (!f.file)
112                 return ERR_PTR(-ENXIO);
113         if (!io_is_uring_fops(f.file)) {
114                 fdput(f);
115                 return ERR_PTR(-EINVAL);
116         }
117
118         ctx_attach = f.file->private_data;
119         sqd = ctx_attach->sq_data;
120         if (!sqd) {
121                 fdput(f);
122                 return ERR_PTR(-EINVAL);
123         }
124         if (sqd->task_tgid != current->tgid) {
125                 fdput(f);
126                 return ERR_PTR(-EPERM);
127         }
128
129         refcount_inc(&sqd->refs);
130         fdput(f);
131         return sqd;
132 }
133
134 static struct io_sq_data *io_get_sq_data(struct io_uring_params *p,
135                                          bool *attached)
136 {
137         struct io_sq_data *sqd;
138
139         *attached = false;
140         if (p->flags & IORING_SETUP_ATTACH_WQ) {
141                 sqd = io_attach_sq_data(p);
142                 if (!IS_ERR(sqd)) {
143                         *attached = true;
144                         return sqd;
145                 }
146                 /* fall through for EPERM case, setup new sqd/task */
147                 if (PTR_ERR(sqd) != -EPERM)
148                         return sqd;
149         }
150
151         sqd = kzalloc(sizeof(*sqd), GFP_KERNEL);
152         if (!sqd)
153                 return ERR_PTR(-ENOMEM);
154
155         atomic_set(&sqd->park_pending, 0);
156         refcount_set(&sqd->refs, 1);
157         INIT_LIST_HEAD(&sqd->ctx_list);
158         mutex_init(&sqd->lock);
159         init_waitqueue_head(&sqd->wait);
160         init_completion(&sqd->exited);
161         return sqd;
162 }
163
164 static inline bool io_sqd_events_pending(struct io_sq_data *sqd)
165 {
166         return READ_ONCE(sqd->state);
167 }
168
169 static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
170 {
171         unsigned int to_submit;
172         int ret = 0;
173
174         to_submit = io_sqring_entries(ctx);
175         /* if we're handling multiple rings, cap submit size for fairness */
176         if (cap_entries && to_submit > IORING_SQPOLL_CAP_ENTRIES_VALUE)
177                 to_submit = IORING_SQPOLL_CAP_ENTRIES_VALUE;
178
179         if (!wq_list_empty(&ctx->iopoll_list) || to_submit) {
180                 const struct cred *creds = NULL;
181
182                 if (ctx->sq_creds != current_cred())
183                         creds = override_creds(ctx->sq_creds);
184
185                 mutex_lock(&ctx->uring_lock);
186                 if (!wq_list_empty(&ctx->iopoll_list))
187                         io_do_iopoll(ctx, true);
188
189                 /*
190                  * Don't submit if refs are dying, good for io_uring_register(),
191                  * but also it is relied upon by io_ring_exit_work()
192                  */
193                 if (to_submit && likely(!percpu_ref_is_dying(&ctx->refs)) &&
194                     !(ctx->flags & IORING_SETUP_R_DISABLED))
195                         ret = io_submit_sqes(ctx, to_submit);
196                 mutex_unlock(&ctx->uring_lock);
197
198                 if (io_napi(ctx))
199                         ret += io_napi_sqpoll_busy_poll(ctx);
200
201                 if (to_submit && wq_has_sleeper(&ctx->sqo_sq_wait))
202                         wake_up(&ctx->sqo_sq_wait);
203                 if (creds)
204                         revert_creds(creds);
205         }
206
207         return ret;
208 }
209
210 static bool io_sqd_handle_event(struct io_sq_data *sqd)
211 {
212         bool did_sig = false;
213         struct ksignal ksig;
214
215         if (test_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state) ||
216             signal_pending(current)) {
217                 mutex_unlock(&sqd->lock);
218                 if (signal_pending(current))
219                         did_sig = get_signal(&ksig);
220                 cond_resched();
221                 mutex_lock(&sqd->lock);
222                 sqd->sq_cpu = raw_smp_processor_id();
223         }
224         return did_sig || test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);
225 }
226
227 /*
228  * Run task_work, processing the retry_list first. The retry_list holds
229  * entries that we passed on in the previous run, if we had more task_work
230  * than we were asked to process. Newly queued task_work isn't run until the
231  * retry list has been fully processed.
232  */
233 static unsigned int io_sq_tw(struct llist_node **retry_list, int max_entries)
234 {
235         struct io_uring_task *tctx = current->io_uring;
236         unsigned int count = 0;
237
238         if (*retry_list) {
239                 *retry_list = io_handle_tw_list(*retry_list, &count, max_entries);
240                 if (count >= max_entries)
241                         return count;
242                 max_entries -= count;
243         }
244
245         *retry_list = tctx_task_work_run(tctx, max_entries, &count);
246         return count;
247 }
248
249 static 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
256 static 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
267 static 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 async
296          * operations that would trigger an audit call before any issue side
297          * 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                 if (sqt_spin || !time_after(jiffies, timeout)) {
324                         if (sqt_spin) {
325                                 io_sq_update_worktime(sqd, &start);
326                                 timeout = jiffies + sqd->sq_thread_idle;
327                         }
328                         if (unlikely(need_resched())) {
329                                 mutex_unlock(&sqd->lock);
330                                 cond_resched();
331                                 mutex_lock(&sqd->lock);
332                                 sqd->sq_cpu = raw_smp_processor_id();
333                         }
334                         continue;
335                 }
336
337                 prepare_to_wait(&sqd->wait, &wait, TASK_INTERRUPTIBLE);
338                 if (!io_sqd_events_pending(sqd) && !io_sq_tw_pending(retry_list)) {
339                         bool needs_sched = true;
340
341                         list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
342                                 atomic_or(IORING_SQ_NEED_WAKEUP,
343                                                 &ctx->rings->sq_flags);
344                                 if ((ctx->flags & IORING_SETUP_IOPOLL) &&
345                                     !wq_list_empty(&ctx->iopoll_list)) {
346                                         needs_sched = false;
347                                         break;
348                                 }
349
350                                 /*
351                                  * Ensure the store of the wakeup flag is not
352                                  * reordered with the load of the SQ tail
353                                  */
354                                 smp_mb__after_atomic();
355
356                                 if (io_sqring_entries(ctx)) {
357                                         needs_sched = false;
358                                         break;
359                                 }
360                         }
361
362                         if (needs_sched) {
363                                 mutex_unlock(&sqd->lock);
364                                 schedule();
365                                 mutex_lock(&sqd->lock);
366                                 sqd->sq_cpu = raw_smp_processor_id();
367                         }
368                         list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
369                                 atomic_andnot(IORING_SQ_NEED_WAKEUP,
370                                                 &ctx->rings->sq_flags);
371                 }
372
373                 finish_wait(&sqd->wait, &wait);
374                 timeout = jiffies + sqd->sq_thread_idle;
375         }
376
377         if (retry_list)
378                 io_sq_tw(&retry_list, UINT_MAX);
379
380         io_uring_cancel_generic(true, sqd);
381         sqd->thread = NULL;
382         list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
383                 atomic_or(IORING_SQ_NEED_WAKEUP, &ctx->rings->sq_flags);
384         io_run_task_work();
385         mutex_unlock(&sqd->lock);
386 err_out:
387         complete(&sqd->exited);
388         do_exit(0);
389 }
390
391 void io_sqpoll_wait_sq(struct io_ring_ctx *ctx)
392 {
393         DEFINE_WAIT(wait);
394
395         do {
396                 if (!io_sqring_full(ctx))
397                         break;
398                 prepare_to_wait(&ctx->sqo_sq_wait, &wait, TASK_INTERRUPTIBLE);
399
400                 if (!io_sqring_full(ctx))
401                         break;
402                 schedule();
403         } while (!signal_pending(current));
404
405         finish_wait(&ctx->sqo_sq_wait, &wait);
406 }
407
408 __cold int io_sq_offload_create(struct io_ring_ctx *ctx,
409                                 struct io_uring_params *p)
410 {
411         int ret;
412
413         /* Retain compatibility with failing for an invalid attach attempt */
414         if ((ctx->flags & (IORING_SETUP_ATTACH_WQ | IORING_SETUP_SQPOLL)) ==
415                                 IORING_SETUP_ATTACH_WQ) {
416                 struct fd f;
417
418                 f = fdget(p->wq_fd);
419                 if (!f.file)
420                         return -ENXIO;
421                 if (!io_is_uring_fops(f.file)) {
422                         fdput(f);
423                         return -EINVAL;
424                 }
425                 fdput(f);
426         }
427         if (ctx->flags & IORING_SETUP_SQPOLL) {
428                 struct task_struct *tsk;
429                 struct io_sq_data *sqd;
430                 bool attached;
431
432                 ret = security_uring_sqpoll();
433                 if (ret)
434                         return ret;
435
436                 sqd = io_get_sq_data(p, &attached);
437                 if (IS_ERR(sqd)) {
438                         ret = PTR_ERR(sqd);
439                         goto err;
440                 }
441
442                 ctx->sq_creds = get_current_cred();
443                 ctx->sq_data = sqd;
444                 ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle);
445                 if (!ctx->sq_thread_idle)
446                         ctx->sq_thread_idle = HZ;
447
448                 io_sq_thread_park(sqd);
449                 list_add(&ctx->sqd_list, &sqd->ctx_list);
450                 io_sqd_update_thread_idle(sqd);
451                 /* don't attach to a dying SQPOLL thread, would be racy */
452                 ret = (attached && !sqd->thread) ? -ENXIO : 0;
453                 io_sq_thread_unpark(sqd);
454
455                 if (ret < 0)
456                         goto err;
457                 if (attached)
458                         return 0;
459
460                 if (p->flags & IORING_SETUP_SQ_AFF) {
461                         int cpu = p->sq_thread_cpu;
462
463                         ret = -EINVAL;
464                         if (cpu >= nr_cpu_ids || !cpu_online(cpu))
465                                 goto err_sqpoll;
466                         sqd->sq_cpu = cpu;
467                 } else {
468                         sqd->sq_cpu = -1;
469                 }
470
471                 sqd->task_pid = current->pid;
472                 sqd->task_tgid = current->tgid;
473                 tsk = create_io_thread(io_sq_thread, sqd, NUMA_NO_NODE);
474                 if (IS_ERR(tsk)) {
475                         ret = PTR_ERR(tsk);
476                         goto err_sqpoll;
477                 }
478
479                 sqd->thread = tsk;
480                 ret = io_uring_alloc_task_context(tsk, ctx);
481                 wake_up_new_task(tsk);
482                 if (ret)
483                         goto err;
484         } else if (p->flags & IORING_SETUP_SQ_AFF) {
485                 /* Can't have SQ_AFF without SQPOLL */
486                 ret = -EINVAL;
487                 goto err;
488         }
489
490         return 0;
491 err_sqpoll:
492         complete(&ctx->sq_data->exited);
493 err:
494         io_sq_thread_finish(ctx);
495         return ret;
496 }
497
498 __cold int io_sqpoll_wq_cpu_affinity(struct io_ring_ctx *ctx,
499                                      cpumask_var_t mask)
500 {
501         struct io_sq_data *sqd = ctx->sq_data;
502         int ret = -EINVAL;
503
504         if (sqd) {
505                 io_sq_thread_park(sqd);
506                 /* Don't set affinity for a dying thread */
507                 if (sqd->thread)
508                         ret = io_wq_cpu_affinity(sqd->thread->io_uring, mask);
509                 io_sq_thread_unpark(sqd);
510         }
511
512         return ret;
513 }
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