1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * ALSA sequencer FIFO 4 * Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl> 5 */ 6 7 #include <sound/core.h> 8 #include <linux/slab.h> 9 #include <linux/sched/signal.h> 10 11 #include "seq_fifo.h" 12 #include "seq_lock.h" 13 14 15 /* FIFO */ 16 17 /* create new fifo */ 18 struct snd_seq_fifo *snd_seq_fifo_new(int poolsize) 19 { 20 struct snd_seq_fifo *f; 21 22 f = kzalloc(sizeof(*f), GFP_KERNEL); 23 if (!f) 24 return NULL; 25 26 f->pool = snd_seq_pool_new(poolsize); 27 if (f->pool == NULL) { 28 kfree(f); 29 return NULL; 30 } 31 if (snd_seq_pool_init(f->pool) < 0) { 32 snd_seq_pool_delete(&f->pool); 33 kfree(f); 34 return NULL; 35 } 36 37 spin_lock_init(&f->lock); 38 snd_use_lock_init(&f->use_lock); 39 init_waitqueue_head(&f->input_sleep); 40 atomic_set(&f->overflow, 0); 41 42 f->head = NULL; 43 f->tail = NULL; 44 f->cells = 0; 45 46 return f; 47 } 48 49 void snd_seq_fifo_delete(struct snd_seq_fifo **fifo) 50 { 51 struct snd_seq_fifo *f; 52 53 if (snd_BUG_ON(!fifo)) 54 return; 55 f = *fifo; 56 if (snd_BUG_ON(!f)) 57 return; 58 *fifo = NULL; 59 60 if (f->pool) 61 snd_seq_pool_mark_closing(f->pool); 62 63 snd_seq_fifo_clear(f); 64 65 /* wake up clients if any */ 66 if (waitqueue_active(&f->input_sleep)) 67 wake_up(&f->input_sleep); 68 69 /* release resources...*/ 70 /*....................*/ 71 72 if (f->pool) { 73 snd_seq_pool_done(f->pool); 74 snd_seq_pool_delete(&f->pool); 75 } 76 77 kfree(f); 78 } 79 80 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f); 81 82 /* clear queue */ 83 void snd_seq_fifo_clear(struct snd_seq_fifo *f) 84 { 85 struct snd_seq_event_cell *cell; 86 87 /* clear overflow flag */ 88 atomic_set(&f->overflow, 0); 89 90 snd_use_lock_sync(&f->use_lock); 91 spin_lock_irq(&f->lock); 92 /* drain the fifo */ 93 while ((cell = fifo_cell_out(f)) != NULL) { 94 snd_seq_cell_free(cell); 95 } 96 spin_unlock_irq(&f->lock); 97 } 98 99 100 /* enqueue event to fifo */ 101 int snd_seq_fifo_event_in(struct snd_seq_fifo *f, 102 struct snd_seq_event *event) 103 { 104 struct snd_seq_event_cell *cell; 105 unsigned long flags; 106 int err; 107 108 if (snd_BUG_ON(!f)) 109 return -EINVAL; 110 111 snd_use_lock_use(&f->use_lock); 112 err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL, NULL); /* always non-blocking */ 113 if (err < 0) { 114 if ((err == -ENOMEM) || (err == -EAGAIN)) 115 atomic_inc(&f->overflow); 116 snd_use_lock_free(&f->use_lock); 117 return err; 118 } 119 120 /* append new cells to fifo */ 121 spin_lock_irqsave(&f->lock, flags); 122 if (f->tail != NULL) 123 f->tail->next = cell; 124 f->tail = cell; 125 if (f->head == NULL) 126 f->head = cell; 127 cell->next = NULL; 128 f->cells++; 129 spin_unlock_irqrestore(&f->lock, flags); 130 131 /* wakeup client */ 132 if (waitqueue_active(&f->input_sleep)) 133 wake_up(&f->input_sleep); 134 135 snd_use_lock_free(&f->use_lock); 136 137 return 0; /* success */ 138 139 } 140 141 /* dequeue cell from fifo */ 142 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f) 143 { 144 struct snd_seq_event_cell *cell; 145 146 cell = f->head; 147 if (cell) { 148 f->head = cell->next; 149 150 /* reset tail if this was the last element */ 151 if (f->tail == cell) 152 f->tail = NULL; 153 154 cell->next = NULL; 155 f->cells--; 156 } 157 158 return cell; 159 } 160 161 /* dequeue cell from fifo and copy on user space */ 162 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f, 163 struct snd_seq_event_cell **cellp, int nonblock) 164 { 165 struct snd_seq_event_cell *cell; 166 unsigned long flags; 167 wait_queue_entry_t wait; 168 169 if (snd_BUG_ON(!f)) 170 return -EINVAL; 171 172 *cellp = NULL; 173 init_waitqueue_entry(&wait, current); 174 spin_lock_irqsave(&f->lock, flags); 175 while ((cell = fifo_cell_out(f)) == NULL) { 176 if (nonblock) { 177 /* non-blocking - return immediately */ 178 spin_unlock_irqrestore(&f->lock, flags); 179 return -EAGAIN; 180 } 181 set_current_state(TASK_INTERRUPTIBLE); 182 add_wait_queue(&f->input_sleep, &wait); 183 spin_unlock_irqrestore(&f->lock, flags); 184 schedule(); 185 spin_lock_irqsave(&f->lock, flags); 186 remove_wait_queue(&f->input_sleep, &wait); 187 if (signal_pending(current)) { 188 spin_unlock_irqrestore(&f->lock, flags); 189 return -ERESTARTSYS; 190 } 191 } 192 spin_unlock_irqrestore(&f->lock, flags); 193 *cellp = cell; 194 195 return 0; 196 } 197 198 199 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f, 200 struct snd_seq_event_cell *cell) 201 { 202 unsigned long flags; 203 204 if (cell) { 205 spin_lock_irqsave(&f->lock, flags); 206 cell->next = f->head; 207 f->head = cell; 208 if (!f->tail) 209 f->tail = cell; 210 f->cells++; 211 spin_unlock_irqrestore(&f->lock, flags); 212 } 213 } 214 215 216 /* polling; return non-zero if queue is available */ 217 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file, 218 poll_table *wait) 219 { 220 poll_wait(file, &f->input_sleep, wait); 221 return (f->cells > 0); 222 } 223 224 /* change the size of pool; all old events are removed */ 225 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize) 226 { 227 struct snd_seq_pool *newpool, *oldpool; 228 struct snd_seq_event_cell *cell, *next, *oldhead; 229 230 if (snd_BUG_ON(!f || !f->pool)) 231 return -EINVAL; 232 233 /* allocate new pool */ 234 newpool = snd_seq_pool_new(poolsize); 235 if (newpool == NULL) 236 return -ENOMEM; 237 if (snd_seq_pool_init(newpool) < 0) { 238 snd_seq_pool_delete(&newpool); 239 return -ENOMEM; 240 } 241 242 spin_lock_irq(&f->lock); 243 /* remember old pool */ 244 oldpool = f->pool; 245 oldhead = f->head; 246 /* exchange pools */ 247 f->pool = newpool; 248 f->head = NULL; 249 f->tail = NULL; 250 f->cells = 0; 251 /* NOTE: overflow flag is not cleared */ 252 spin_unlock_irq(&f->lock); 253 254 /* close the old pool and wait until all users are gone */ 255 snd_seq_pool_mark_closing(oldpool); 256 snd_use_lock_sync(&f->use_lock); 257 258 /* release cells in old pool */ 259 for (cell = oldhead; cell; cell = next) { 260 next = cell->next; 261 snd_seq_cell_free(cell); 262 } 263 snd_seq_pool_delete(&oldpool); 264 265 return 0; 266 } 267 268 /* get the number of unused cells safely */ 269 int snd_seq_fifo_unused_cells(struct snd_seq_fifo *f) 270 { 271 unsigned long flags; 272 int cells; 273 274 if (!f) 275 return 0; 276 277 snd_use_lock_use(&f->use_lock); 278 spin_lock_irqsave(&f->lock, flags); 279 cells = snd_seq_unused_cells(f->pool); 280 spin_unlock_irqrestore(&f->lock, flags); 281 snd_use_lock_free(&f->use_lock); 282 return cells; 283 } 284