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 guard(spinlock_irq)(&f->lock); 92 /* drain the fifo */ 93 while ((cell = fifo_cell_out(f)) != NULL) { 94 snd_seq_cell_free(cell); 95 } 96 } 97 98 99 /* enqueue event to fifo */ 100 int snd_seq_fifo_event_in(struct snd_seq_fifo *f, 101 struct snd_seq_event *event) 102 { 103 struct snd_seq_event_cell *cell; 104 int err; 105 106 if (snd_BUG_ON(!f)) 107 return -EINVAL; 108 109 guard(snd_seq_fifo)(f); 110 err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL, NULL); /* always non-blocking */ 111 if (err < 0) { 112 if ((err == -ENOMEM) || (err == -EAGAIN)) 113 atomic_inc(&f->overflow); 114 return err; 115 } 116 117 /* append new cells to fifo */ 118 scoped_guard(spinlock_irqsave, &f->lock) { 119 if (f->tail != NULL) 120 f->tail->next = cell; 121 f->tail = cell; 122 if (f->head == NULL) 123 f->head = cell; 124 cell->next = NULL; 125 f->cells++; 126 } 127 128 /* wakeup client */ 129 if (waitqueue_active(&f->input_sleep)) 130 wake_up(&f->input_sleep); 131 132 return 0; /* success */ 133 134 } 135 136 /* dequeue cell from fifo */ 137 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f) 138 { 139 struct snd_seq_event_cell *cell; 140 141 cell = f->head; 142 if (cell) { 143 f->head = cell->next; 144 145 /* reset tail if this was the last element */ 146 if (f->tail == cell) 147 f->tail = NULL; 148 149 cell->next = NULL; 150 f->cells--; 151 } 152 153 return cell; 154 } 155 156 /* dequeue cell from fifo and copy on user space */ 157 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f, 158 struct snd_seq_event_cell **cellp, int nonblock) 159 { 160 struct snd_seq_event_cell *cell; 161 unsigned long flags; 162 wait_queue_entry_t wait; 163 164 if (snd_BUG_ON(!f)) 165 return -EINVAL; 166 167 *cellp = NULL; 168 init_waitqueue_entry(&wait, current); 169 spin_lock_irqsave(&f->lock, flags); 170 while ((cell = fifo_cell_out(f)) == NULL) { 171 if (nonblock) { 172 /* non-blocking - return immediately */ 173 spin_unlock_irqrestore(&f->lock, flags); 174 return -EAGAIN; 175 } 176 set_current_state(TASK_INTERRUPTIBLE); 177 add_wait_queue(&f->input_sleep, &wait); 178 spin_unlock_irqrestore(&f->lock, flags); 179 schedule(); 180 spin_lock_irqsave(&f->lock, flags); 181 remove_wait_queue(&f->input_sleep, &wait); 182 if (signal_pending(current)) { 183 spin_unlock_irqrestore(&f->lock, flags); 184 return -ERESTARTSYS; 185 } 186 } 187 spin_unlock_irqrestore(&f->lock, flags); 188 *cellp = cell; 189 190 return 0; 191 } 192 193 194 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f, 195 struct snd_seq_event_cell *cell) 196 { 197 if (cell) { 198 guard(spinlock_irqsave)(&f->lock); 199 cell->next = f->head; 200 f->head = cell; 201 if (!f->tail) 202 f->tail = cell; 203 f->cells++; 204 } 205 } 206 207 208 /* polling; return non-zero if queue is available */ 209 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file, 210 poll_table *wait) 211 { 212 poll_wait(file, &f->input_sleep, wait); 213 return (f->cells > 0); 214 } 215 216 /* change the size of pool; all old events are removed */ 217 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize) 218 { 219 struct snd_seq_pool *newpool, *oldpool; 220 struct snd_seq_event_cell *cell, *next, *oldhead; 221 222 if (snd_BUG_ON(!f || !f->pool)) 223 return -EINVAL; 224 225 /* allocate new pool */ 226 newpool = snd_seq_pool_new(poolsize); 227 if (newpool == NULL) 228 return -ENOMEM; 229 if (snd_seq_pool_init(newpool) < 0) { 230 snd_seq_pool_delete(&newpool); 231 return -ENOMEM; 232 } 233 234 scoped_guard(spinlock_irq, &f->lock) { 235 /* remember old pool */ 236 oldpool = f->pool; 237 oldhead = f->head; 238 /* exchange pools */ 239 f->pool = newpool; 240 f->head = NULL; 241 f->tail = NULL; 242 f->cells = 0; 243 /* NOTE: overflow flag is not cleared */ 244 } 245 246 /* close the old pool and wait until all users are gone */ 247 snd_seq_pool_mark_closing(oldpool); 248 snd_use_lock_sync(&f->use_lock); 249 250 /* release cells in old pool */ 251 for (cell = oldhead; cell; cell = next) { 252 next = cell->next; 253 snd_seq_cell_free(cell); 254 } 255 snd_seq_pool_delete(&oldpool); 256 257 return 0; 258 } 259 260 /* get the number of unused cells safely */ 261 int snd_seq_fifo_unused_cells(struct snd_seq_fifo *f) 262 { 263 if (!f) 264 return 0; 265 266 guard(snd_seq_fifo)(f); 267 guard(spinlock_irqsave)(&f->lock); 268 return snd_seq_unused_cells(f->pool); 269 } 270