diff --git a/drivers/staging/most/aim-cdev/cdev.c b/drivers/staging/most/aim-cdev/cdev.c index 5458fb932d86..7f51024dc5eb 100644 --- a/drivers/staging/most/aim-cdev/cdev.c +++ b/drivers/staging/most/aim-cdev/cdev.c @@ -57,7 +57,11 @@ static inline bool ch_has_mbo(struct aim_channel *c) static inline bool ch_get_mbo(struct aim_channel *c, struct mbo **mbo) { - *mbo = most_get_mbo(c->iface, c->channel_id, &cdev_aim); + if (!kfifo_peek(&c->fifo, mbo)) { + *mbo = most_get_mbo(c->iface, c->channel_id, &cdev_aim); + if (*mbo) + kfifo_in(&c->fifo, mbo, 1); + } return *mbo; } @@ -184,8 +188,7 @@ static ssize_t aim_write(struct file *filp, const char __user *buf, size_t count, loff_t *offset) { int ret; - size_t actual_len; - size_t max_len; + size_t to_copy, left; struct mbo *mbo = NULL; struct aim_channel *c = filp->private_data; @@ -205,20 +208,24 @@ static ssize_t aim_write(struct file *filp, const char __user *buf, goto unlock; } - max_len = c->cfg->buffer_size; - actual_len = min(count, max_len); - mbo->buffer_length = actual_len; - - if (copy_from_user(mbo->virt_address, buf, mbo->buffer_length)) { + to_copy = min(count, c->cfg->buffer_size - c->mbo_offs); + left = copy_from_user(mbo->virt_address + c->mbo_offs, buf, to_copy); + if (left == to_copy) { ret = -EFAULT; - goto put_mbo; + goto unlock; } - most_submit_mbo(mbo); - mutex_unlock(&c->io_mutex); - return actual_len; -put_mbo: - most_put_mbo(mbo); + c->mbo_offs += to_copy - left; + if (c->mbo_offs >= c->cfg->buffer_size || + c->cfg->data_type == MOST_CH_CONTROL || + c->cfg->data_type == MOST_CH_ASYNC) { + kfifo_skip(&c->fifo); + mbo->buffer_length = c->mbo_offs; + c->mbo_offs = 0; + most_submit_mbo(mbo); + } + + ret = to_copy - left; unlock: mutex_unlock(&c->io_mutex); return ret; @@ -287,7 +294,7 @@ static unsigned int aim_poll(struct file *filp, poll_table *wait) if (!kfifo_is_empty(&c->fifo)) mask |= POLLIN | POLLRDNORM; } else { - if (ch_has_mbo(c)) + if (!kfifo_is_empty(&c->fifo) || ch_has_mbo(c)) mask |= POLLOUT | POLLWRNORM; } return mask;