From da2c08714c94780d81780dd8918c71d491f672f4 Mon Sep 17 00:00:00 2001 From: Christian Gromm Date: Fri, 23 Sep 2016 15:20:02 +0200 Subject: [PATCH] staging: most: aim-cdev: make syscall write accept buffers of arbitrary size This patch allows to call the write() function for synchronous and isochronous channels with buffers of any size. The AIM simply waits for data to fill up the MOST buffer object according to the network interface controller specification for streaming channels, before it submits the buffer to the HDM. The new behavior is backward compatible to the old applications, since all known applications needed to fill the buffer completely anyway. Signed-off-by: Christian Gromm Signed-off-by: Greg Kroah-Hartman --- drivers/staging/most/aim-cdev/cdev.c | 37 +++++++++++++++++----------- 1 file changed, 22 insertions(+), 15 deletions(-) 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; -- 2.45.2