io_uring/tctx.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/kernel.h>
   3 #include <linux/errno.h>
   4 #include <linux/file.h>
   5 #include <linux/mm.h>
   6 #include <linux/slab.h>
   7 #include <linux/nospec.h>
   8 #include <linux/io_uring.h>
   9
  10 #include <uapi/linux/io_uring.h>
  11
  12 #include "io_uring.h"
  13 #include "tctx.h"
  14
  15 static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx,
  16                                         struct task_struct *task)
  17 {
  18         struct io_wq_hash *hash;
  19         struct io_wq_data data;
  20         unsigned int concurrency;
  21
  22         mutex_lock(&ctx->uring_lock);
  23         hash = ctx->hash_map;
  24         if (!hash) {
  25                 hash = kzalloc(sizeof(*hash), GFP_KERNEL);
  26                 if (!hash) {
  27                         mutex_unlock(&ctx->uring_lock);
  28                         return ERR_PTR(-ENOMEM);
  29                 }
  30                 refcount_set(&hash->refs, 1);
  31                 init_waitqueue_head(&hash->wait);
  32                 ctx->hash_map = hash;
  33         }
  34         mutex_unlock(&ctx->uring_lock);
  35
  36         data.hash = hash;
  37         data.task = task;
  38         data.free_work = io_wq_free_work;
  39         data.do_work = io_wq_submit_work;
  40
  41         /* Do QD, or 4 * CPUS, whatever is smallest */
  42         concurrency = min(ctx->sq_entries, 4 * num_online_cpus());
  43
  44         return io_wq_create(concurrency, &data);
  45 }
  46
  47 void __io_uring_free(struct task_struct *tsk)
  48 {
  49         struct io_uring_task *tctx = tsk->io_uring;
  50
  51         WARN_ON_ONCE(!xa_empty(&tctx->xa));
  52         WARN_ON_ONCE(tctx->io_wq);
  53         WARN_ON_ONCE(tctx->cached_refs);
  54
  55         percpu_counter_destroy(&tctx->inflight);
  56         kfree(tctx);
  57         tsk->io_uring = NULL;
  58 }
  59
  60 __cold int io_uring_alloc_task_context(struct task_struct *task,
  61                                        struct io_ring_ctx *ctx)
  62 {
  63         struct io_uring_task *tctx;
  64         int ret;
  65
  66         tctx = kzalloc(sizeof(*tctx), GFP_KERNEL);
  67         if (unlikely(!tctx))
  68                 return -ENOMEM;
  69
  70         ret = percpu_counter_init(&tctx->inflight, 0, GFP_KERNEL);
  71         if (unlikely(ret)) {
  72                 kfree(tctx);
  73                 return ret;
  74         }
  75
  76         tctx->io_wq = io_init_wq_offload(ctx, task);
  77         if (IS_ERR(tctx->io_wq)) {
  78                 ret = PTR_ERR(tctx->io_wq);
  79                 percpu_counter_destroy(&tctx->inflight);
  80                 kfree(tctx);
  81                 return ret;
  82         }
  83
  84         xa_init(&tctx->xa);
  85         init_waitqueue_head(&tctx->wait);
  86         atomic_set(&tctx->in_cancel, 0);
  87         atomic_set(&tctx->inflight_tracked, 0);
  88         task->io_uring = tctx;
  89         init_llist_head(&tctx->task_list);
  90         init_task_work(&tctx->task_work, tctx_task_work);
  91         return 0;
  92 }
  93
  94 int __io_uring_add_tctx_node(struct io_ring_ctx *ctx)
  95 {
  96         struct io_uring_task *tctx = current->io_uring;
  97         struct io_tctx_node *node;
  98         int ret;
  99
 100         if (unlikely(!tctx)) {
 101                 ret = io_uring_alloc_task_context(current, ctx);
 102                 if (unlikely(ret))
 103                         return ret;
 104
 105                 tctx = current->io_uring;
 106                 if (ctx->iowq_limits_set) {
 107                         unsigned int limits[2] = { ctx->iowq_limits[0],
 108                                                    ctx->iowq_limits[1], };
 109
 110                         ret = io_wq_max_workers(tctx->io_wq, limits);
 111                         if (ret)
 112                                 return ret;
 113                 }
 114         }
 115         if (!xa_load(&tctx->xa, (unsigned long)ctx)) {
 116                 node = kmalloc(sizeof(*node), GFP_KERNEL);
 117                 if (!node)
 118                         return -ENOMEM;
 119                 node->ctx = ctx;
 120                 node->task = current;
 121
 122                 ret = xa_err(xa_store(&tctx->xa, (unsigned long)ctx,
 123                                         node, GFP_KERNEL));
 124                 if (ret) {
 125                         kfree(node);
 126                         return ret;
 127                 }
 128
 129                 mutex_lock(&ctx->uring_lock);
 130                 list_add(&node->ctx_node, &ctx->tctx_list);
 131                 mutex_unlock(&ctx->uring_lock);
 132         }
 133         return 0;
 134 }
 135
 136 int __io_uring_add_tctx_node_from_submit(struct io_ring_ctx *ctx)
 137 {
 138         int ret;
 139
 140         if (ctx->flags & IORING_SETUP_SINGLE_ISSUER
 141             && ctx->submitter_task != current)
 142                 return -EEXIST;
 143
 144         ret = __io_uring_add_tctx_node(ctx);
 145         if (ret)
 146                 return ret;
 147
 148         current->io_uring->last = ctx;
 149         return 0;
 150 }
 151
 152 /*
 153  * Remove this io_uring_file -> task mapping.
 154  */
 155 __cold void io_uring_del_tctx_node(unsigned long index)
 156 {
 157         struct io_uring_task *tctx = current->io_uring;
 158         struct io_tctx_node *node;
 159
 160         if (!tctx)
 161                 return;
 162         node = xa_erase(&tctx->xa, index);
 163         if (!node)
 164                 return;
 165
 166         WARN_ON_ONCE(current != node->task);
 167         WARN_ON_ONCE(list_empty(&node->ctx_node));
 168
 169         mutex_lock(&node->ctx->uring_lock);
 170         list_del(&node->ctx_node);
 171         mutex_unlock(&node->ctx->uring_lock);
 172
 173         if (tctx->last == node->ctx)
 174                 tctx->last = NULL;
 175         kfree(node);
 176 }
 177
 178 __cold void io_uring_clean_tctx(struct io_uring_task *tctx)
 179 {
 180         struct io_wq *wq = tctx->io_wq;
 181         struct io_tctx_node *node;
 182         unsigned long index;
 183
 184         xa_for_each(&tctx->xa, index, node) {
 185                 io_uring_del_tctx_node(index);
 186                 cond_resched();
 187         }
 188         if (wq) {
 189                 /*
 190                  * Must be after io_uring_del_tctx_node() (removes nodes under
 191                  * uring_lock) to avoid race with io_uring_try_cancel_iowq().
 192                  */
 193                 io_wq_put_and_exit(wq);
 194                 tctx->io_wq = NULL;
 195         }
 196 }
 197
 198 void io_uring_unreg_ringfd(void)
 199 {
 200         struct io_uring_task *tctx = current->io_uring;
 201         int i;
 202
 203         for (i = 0; i < IO_RINGFD_REG_MAX; i++) {
 204                 if (tctx->registered_rings[i]) {
 205                         fput(tctx->registered_rings[i]);
 206                         tctx->registered_rings[i] = NULL;
 207                 }
 208         }
 209 }
 210
 211 int io_ring_add_registered_file(struct io_uring_task *tctx, struct file *file,
 212                                      int start, int end)
 213 {
 214         int offset;
 215         for (offset = start; offset < end; offset++) {
 216                 offset = array_index_nospec(offset, IO_RINGFD_REG_MAX);
 217                 if (tctx->registered_rings[offset])
 218                         continue;
 219
 220                 tctx->registered_rings[offset] = file;
 221                 return offset;
 222         }
 223         return -EBUSY;
 224 }
 225
 226 static int io_ring_add_registered_fd(struct io_uring_task *tctx, int fd,
 227                                      int start, int end)
 228 {
 229         struct file *file;
 230         int offset;
 231
 232         file = fget(fd);
 233         if (!file) {
 234                 return -EBADF;
 235         } else if (!io_is_uring_fops(file)) {
 236                 fput(file);
 237                 return -EOPNOTSUPP;
 238         }
 239         offset = io_ring_add_registered_file(tctx, file, start, end);
 240         if (offset < 0)
 241                 fput(file);
 242         return offset;
 243 }
 244
 245 /*
 246  * Register a ring fd to avoid fdget/fdput for each io_uring_enter()
 247  * invocation. User passes in an array of struct io_uring_rsrc_update
 248  * with ->data set to the ring_fd, and ->offset given for the desired
 249  * index. If no index is desired, application may set ->offset == -1U
 250  * and we'll find an available index. Returns number of entries
 251  * successfully processed, or < 0 on error if none were processed.
 252  */
 253 int io_ringfd_register(struct io_ring_ctx *ctx, void __user *__arg,
 254                        unsigned nr_args)
 255 {
 256         struct io_uring_rsrc_update __user *arg = __arg;
 257         struct io_uring_rsrc_update reg;
 258         struct io_uring_task *tctx;
 259         int ret, i;
 260
 261         if (!nr_args || nr_args > IO_RINGFD_REG_MAX)
 262                 return -EINVAL;
 263
 264         mutex_unlock(&ctx->uring_lock);
 265         ret = __io_uring_add_tctx_node(ctx);
 266         mutex_lock(&ctx->uring_lock);
 267         if (ret)
 268                 return ret;
 269
 270         tctx = current->io_uring;
 271         for (i = 0; i < nr_args; i++) {
 272                 int start, end;
 273
 274                 if (copy_from_user(&reg, &arg[i], sizeof(reg))) {
 275                         ret = -EFAULT;
 276                         break;
 277                 }
 278
 279                 if (reg.resv) {
 280                         ret = -EINVAL;
 281                         break;
 282                 }
 283
 284                 if (reg.offset == -1U) {
 285                         start = 0;
 286                         end = IO_RINGFD_REG_MAX;
 287                 } else {
 288                         if (reg.offset >= IO_RINGFD_REG_MAX) {
 289                                 ret = -EINVAL;
 290                                 break;
 291                         }
 292                         start = reg.offset;
 293                         end = start + 1;
 294                 }
 295
 296                 ret = io_ring_add_registered_fd(tctx, reg.data, start, end);
 297                 if (ret < 0)
 298                         break;
 299
 300                 reg.offset = ret;
 301                 if (copy_to_user(&arg[i], &reg, sizeof(reg))) {
 302                         fput(tctx->registered_rings[reg.offset]);
 303                         tctx->registered_rings[reg.offset] = NULL;
 304                         ret = -EFAULT;
 305                         break;
 306                 }
 307         }
 308
 309         return i ? i : ret;
 310 }
 311
 312 int io_ringfd_unregister(struct io_ring_ctx *ctx, void __user *__arg,
 313                          unsigned nr_args)
 314 {
 315         struct io_uring_rsrc_update __user *arg = __arg;
 316         struct io_uring_task *tctx = current->io_uring;
 317         struct io_uring_rsrc_update reg;
 318         int ret = 0, i;
 319
 320         if (!nr_args || nr_args > IO_RINGFD_REG_MAX)
 321                 return -EINVAL;
 322         if (!tctx)
 323                 return 0;
 324
 325         for (i = 0; i < nr_args; i++) {
 326                 if (copy_from_user(&reg, &arg[i], sizeof(reg))) {
 327                         ret = -EFAULT;
 328                         break;
 329                 }
 330                 if (reg.resv || reg.data || reg.offset >= IO_RINGFD_REG_MAX) {
 331                         ret = -EINVAL;
 332                         break;
 333                 }
 334
 335                 reg.offset = array_index_nospec(reg.offset, IO_RINGFD_REG_MAX);
 336                 if (tctx->registered_rings[reg.offset]) {
 337                         fput(tctx->registered_rings[reg.offset]);
 338                         tctx->registered_rings[reg.offset] = NULL;
 339                 }
 340         }
 341
 342         return i ? i : ret;
 343 }