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 if ((cell = f->head) != NULL) { 147 f->head = cell->next; 148 149 /* reset tail if this was the last element */ 150 if (f->tail == cell) 151 f->tail = NULL; 152 153 cell->next = NULL; 154 f->cells--; 155 } 156 157 return cell; 158 } 159 160 /* dequeue cell from fifo and copy on user space */ 161 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f, 162 struct snd_seq_event_cell **cellp, int nonblock) 163 { 164 struct snd_seq_event_cell *cell; 165 unsigned long flags; 166 wait_queue_entry_t wait; 167 168 if (snd_BUG_ON(!f)) 169 return -EINVAL; 170 171 *cellp = NULL; 172 init_waitqueue_entry(&wait, current); 173 spin_lock_irqsave(&f->lock, flags); 174 while ((cell = fifo_cell_out(f)) == NULL) { 175 if (nonblock) { 176 /* non-blocking - return immediately */ 177 spin_unlock_irqrestore(&f->lock, flags); 178 return -EAGAIN; 179 } 180 set_current_state(TASK_INTERRUPTIBLE); 181 add_wait_queue(&f->input_sleep, &wait); 182 spin_unlock_irqrestore(&f->lock, flags); 183 schedule(); 184 spin_lock_irqsave(&f->lock, flags); 185 remove_wait_queue(&f->input_sleep, &wait); 186 if (signal_pending(current)) { 187 spin_unlock_irqrestore(&f->lock, flags); 188 return -ERESTARTSYS; 189 } 190 } 191 spin_unlock_irqrestore(&f->lock, flags); 192 *cellp = cell; 193 194 return 0; 195 } 196 197 198 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f, 199 struct snd_seq_event_cell *cell) 200 { 201 unsigned long flags; 202 203 if (cell) { 204 spin_lock_irqsave(&f->lock, flags); 205 cell->next = f->head; 206 f->head = cell; 207 if (!f->tail) 208 f->tail = cell; 209 f->cells++; 210 spin_unlock_irqrestore(&f->lock, flags); 211 } 212 } 213 214 215 /* polling; return non-zero if queue is available */ 216 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file, 217 poll_table *wait) 218 { 219 poll_wait(file, &f->input_sleep, wait); 220 return (f->cells > 0); 221 } 222 223 /* change the size of pool; all old events are removed */ 224 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize) 225 { 226 struct snd_seq_pool *newpool, *oldpool; 227 struct snd_seq_event_cell *cell, *next, *oldhead; 228 229 if (snd_BUG_ON(!f || !f->pool)) 230 return -EINVAL; 231 232 /* allocate new pool */ 233 newpool = snd_seq_pool_new(poolsize); 234 if (newpool == NULL) 235 return -ENOMEM; 236 if (snd_seq_pool_init(newpool) < 0) { 237 snd_seq_pool_delete(&newpool); 238 return -ENOMEM; 239 } 240 241 spin_lock_irq(&f->lock); 242 /* remember old pool */ 243 oldpool = f->pool; 244 oldhead = f->head; 245 /* exchange pools */ 246 f->pool = newpool; 247 f->head = NULL; 248 f->tail = NULL; 249 f->cells = 0; 250 /* NOTE: overflow flag is not cleared */ 251 spin_unlock_irq(&f->lock); 252 253 /* close the old pool and wait until all users are gone */ 254 snd_seq_pool_mark_closing(oldpool); 255 snd_use_lock_sync(&f->use_lock); 256 257 /* release cells in old pool */ 258 for (cell = oldhead; cell; cell = next) { 259 next = cell->next; 260 snd_seq_cell_free(cell); 261 } 262 snd_seq_pool_delete(&oldpool); 263 264 return 0; 265 } 266 267 /* get the number of unused cells safely */ 268 int snd_seq_fifo_unused_cells(struct snd_seq_fifo *f) 269 { 270 unsigned long flags; 271 int cells; 272 273 if (!f) 274 return 0; 275 276 snd_use_lock_use(&f->use_lock); 277 spin_lock_irqsave(&f->lock, flags); 278 cells = snd_seq_unused_cells(f->pool); 279 spin_unlock_irqrestore(&f->lock, flags); 280 snd_use_lock_free(&f->use_lock); 281 return cells; 282 } 283