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369 lines
9.9 KiB
369 lines
9.9 KiB
/* |
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* |
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* dvb_ringbuffer.c: ring buffer implementation for the dvb driver |
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* |
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* Copyright (C) 2003 Oliver Endriss |
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* Copyright (C) 2004 Andrew de Quincey |
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* |
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* based on code originally found in av7110.c & dvb_ci.c: |
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* Copyright (C) 1999-2003 Ralph Metzler |
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* & Marcus Metzler for convergence integrated media GmbH |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public License |
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* as published by the Free Software Foundation; either version 2.1 |
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* of the License, or (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU Lesser General Public License for more details. |
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*/ |
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#include <linux/errno.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/sched.h> |
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#include <linux/string.h> |
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#include <linux/uaccess.h> |
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#include <media/dvb_ringbuffer.h> |
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#define PKT_READY 0 |
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#define PKT_DISPOSED 1 |
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void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len) |
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{ |
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rbuf->pread=rbuf->pwrite=0; |
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rbuf->data=data; |
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rbuf->size=len; |
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rbuf->error=0; |
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init_waitqueue_head(&rbuf->queue); |
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spin_lock_init(&(rbuf->lock)); |
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} |
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int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf) |
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{ |
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/* smp_load_acquire() to load write pointer on reader side |
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* this pairs with smp_store_release() in dvb_ringbuffer_write(), |
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* dvb_ringbuffer_write_user(), or dvb_ringbuffer_reset() |
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* |
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* for memory barriers also see Documentation/core-api/circular-buffers.rst |
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*/ |
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return (rbuf->pread == smp_load_acquire(&rbuf->pwrite)); |
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} |
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ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf) |
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{ |
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ssize_t free; |
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/* READ_ONCE() to load read pointer on writer side |
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* this pairs with smp_store_release() in dvb_ringbuffer_read(), |
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* dvb_ringbuffer_read_user(), dvb_ringbuffer_flush(), |
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* or dvb_ringbuffer_reset() |
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*/ |
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free = READ_ONCE(rbuf->pread) - rbuf->pwrite; |
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if (free <= 0) |
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free += rbuf->size; |
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return free-1; |
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} |
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ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf) |
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{ |
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ssize_t avail; |
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/* smp_load_acquire() to load write pointer on reader side |
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* this pairs with smp_store_release() in dvb_ringbuffer_write(), |
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* dvb_ringbuffer_write_user(), or dvb_ringbuffer_reset() |
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*/ |
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avail = smp_load_acquire(&rbuf->pwrite) - rbuf->pread; |
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if (avail < 0) |
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avail += rbuf->size; |
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return avail; |
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} |
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void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf) |
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{ |
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/* dvb_ringbuffer_flush() counts as read operation |
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* smp_load_acquire() to load write pointer |
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* smp_store_release() to update read pointer, this ensures that the |
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* correct pointer is visible for subsequent dvb_ringbuffer_free() |
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* calls on other cpu cores |
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*/ |
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smp_store_release(&rbuf->pread, smp_load_acquire(&rbuf->pwrite)); |
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rbuf->error = 0; |
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} |
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EXPORT_SYMBOL(dvb_ringbuffer_flush); |
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void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf) |
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{ |
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/* dvb_ringbuffer_reset() counts as read and write operation |
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* smp_store_release() to update read pointer |
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*/ |
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smp_store_release(&rbuf->pread, 0); |
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/* smp_store_release() to update write pointer */ |
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smp_store_release(&rbuf->pwrite, 0); |
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rbuf->error = 0; |
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} |
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void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf) |
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{ |
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unsigned long flags; |
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spin_lock_irqsave(&rbuf->lock, flags); |
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dvb_ringbuffer_flush(rbuf); |
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spin_unlock_irqrestore(&rbuf->lock, flags); |
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wake_up(&rbuf->queue); |
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} |
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ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf, u8 __user *buf, size_t len) |
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{ |
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size_t todo = len; |
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size_t split; |
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split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0; |
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if (split > 0) { |
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if (copy_to_user(buf, rbuf->data+rbuf->pread, split)) |
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return -EFAULT; |
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buf += split; |
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todo -= split; |
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/* smp_store_release() for read pointer update to ensure |
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* that buf is not overwritten until read is complete, |
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* this pairs with READ_ONCE() in dvb_ringbuffer_free() |
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*/ |
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smp_store_release(&rbuf->pread, 0); |
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} |
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if (copy_to_user(buf, rbuf->data+rbuf->pread, todo)) |
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return -EFAULT; |
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/* smp_store_release() to update read pointer, see above */ |
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smp_store_release(&rbuf->pread, (rbuf->pread + todo) % rbuf->size); |
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return len; |
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} |
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void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len) |
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{ |
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size_t todo = len; |
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size_t split; |
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split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0; |
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if (split > 0) { |
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memcpy(buf, rbuf->data+rbuf->pread, split); |
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buf += split; |
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todo -= split; |
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/* smp_store_release() for read pointer update to ensure |
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* that buf is not overwritten until read is complete, |
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* this pairs with READ_ONCE() in dvb_ringbuffer_free() |
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*/ |
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smp_store_release(&rbuf->pread, 0); |
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} |
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memcpy(buf, rbuf->data+rbuf->pread, todo); |
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/* smp_store_release() to update read pointer, see above */ |
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smp_store_release(&rbuf->pread, (rbuf->pread + todo) % rbuf->size); |
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} |
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ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len) |
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{ |
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size_t todo = len; |
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size_t split; |
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split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0; |
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if (split > 0) { |
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memcpy(rbuf->data+rbuf->pwrite, buf, split); |
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buf += split; |
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todo -= split; |
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/* smp_store_release() for write pointer update to ensure that |
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* written data is visible on other cpu cores before the pointer |
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* update, this pairs with smp_load_acquire() in |
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* dvb_ringbuffer_empty() or dvb_ringbuffer_avail() |
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*/ |
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smp_store_release(&rbuf->pwrite, 0); |
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} |
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memcpy(rbuf->data+rbuf->pwrite, buf, todo); |
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/* smp_store_release() for write pointer update, see above */ |
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smp_store_release(&rbuf->pwrite, (rbuf->pwrite + todo) % rbuf->size); |
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return len; |
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} |
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ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf, |
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const u8 __user *buf, size_t len) |
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{ |
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int status; |
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size_t todo = len; |
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size_t split; |
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split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0; |
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if (split > 0) { |
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status = copy_from_user(rbuf->data+rbuf->pwrite, buf, split); |
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if (status) |
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return len - todo; |
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buf += split; |
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todo -= split; |
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/* smp_store_release() for write pointer update to ensure that |
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* written data is visible on other cpu cores before the pointer |
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* update, this pairs with smp_load_acquire() in |
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* dvb_ringbuffer_empty() or dvb_ringbuffer_avail() |
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*/ |
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smp_store_release(&rbuf->pwrite, 0); |
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} |
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status = copy_from_user(rbuf->data+rbuf->pwrite, buf, todo); |
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if (status) |
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return len - todo; |
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/* smp_store_release() for write pointer update, see above */ |
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smp_store_release(&rbuf->pwrite, (rbuf->pwrite + todo) % rbuf->size); |
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return len; |
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} |
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ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len) |
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{ |
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int status; |
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ssize_t oldpwrite = rbuf->pwrite; |
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DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8); |
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DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff); |
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DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY); |
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status = dvb_ringbuffer_write(rbuf, buf, len); |
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if (status < 0) rbuf->pwrite = oldpwrite; |
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return status; |
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} |
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ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx, |
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int offset, u8 __user *buf, size_t len) |
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{ |
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size_t todo; |
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size_t split; |
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size_t pktlen; |
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pktlen = rbuf->data[idx] << 8; |
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pktlen |= rbuf->data[(idx + 1) % rbuf->size]; |
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if (offset > pktlen) return -EINVAL; |
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if ((offset + len) > pktlen) len = pktlen - offset; |
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idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size; |
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todo = len; |
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split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0; |
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if (split > 0) { |
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if (copy_to_user(buf, rbuf->data+idx, split)) |
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return -EFAULT; |
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buf += split; |
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todo -= split; |
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idx = 0; |
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} |
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if (copy_to_user(buf, rbuf->data+idx, todo)) |
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return -EFAULT; |
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return len; |
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} |
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ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx, |
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int offset, u8* buf, size_t len) |
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{ |
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size_t todo; |
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size_t split; |
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size_t pktlen; |
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pktlen = rbuf->data[idx] << 8; |
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pktlen |= rbuf->data[(idx + 1) % rbuf->size]; |
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if (offset > pktlen) return -EINVAL; |
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if ((offset + len) > pktlen) len = pktlen - offset; |
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idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size; |
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todo = len; |
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split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0; |
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if (split > 0) { |
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memcpy(buf, rbuf->data+idx, split); |
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buf += split; |
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todo -= split; |
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idx = 0; |
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} |
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memcpy(buf, rbuf->data+idx, todo); |
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return len; |
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} |
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void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx) |
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{ |
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size_t pktlen; |
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rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED; |
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// clean up disposed packets |
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while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) { |
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if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) { |
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pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8; |
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pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1); |
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DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE); |
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} else { |
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// first packet is not disposed, so we stop cleaning now |
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break; |
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} |
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} |
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} |
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ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen) |
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{ |
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int consumed; |
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int curpktlen; |
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int curpktstatus; |
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if (idx == -1) { |
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idx = rbuf->pread; |
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} else { |
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curpktlen = rbuf->data[idx] << 8; |
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curpktlen |= rbuf->data[(idx + 1) % rbuf->size]; |
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idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size; |
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} |
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consumed = (idx - rbuf->pread) % rbuf->size; |
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while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) { |
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curpktlen = rbuf->data[idx] << 8; |
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curpktlen |= rbuf->data[(idx + 1) % rbuf->size]; |
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curpktstatus = rbuf->data[(idx + 2) % rbuf->size]; |
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if (curpktstatus == PKT_READY) { |
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*pktlen = curpktlen; |
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return idx; |
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} |
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consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE; |
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idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size; |
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} |
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// no packets available |
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return -1; |
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} |
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EXPORT_SYMBOL(dvb_ringbuffer_init); |
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EXPORT_SYMBOL(dvb_ringbuffer_empty); |
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EXPORT_SYMBOL(dvb_ringbuffer_free); |
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EXPORT_SYMBOL(dvb_ringbuffer_avail); |
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EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup); |
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EXPORT_SYMBOL(dvb_ringbuffer_read_user); |
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EXPORT_SYMBOL(dvb_ringbuffer_read); |
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EXPORT_SYMBOL(dvb_ringbuffer_write); |
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EXPORT_SYMBOL(dvb_ringbuffer_write_user);
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