On Mon, Feb 06, 2012 at 08:23:40AM +0200, Kalle Valo wrote:
> When debugging firmware issues it's not always enough to get
> the latest firmware logs, sometimes we need to get logs from a longer
> period. To make this possible, add a debugfs file named fwlog_block. When
> reading from this file ath6kl will send firmware logs whenever available
> and otherwise it will block and wait for new logs.
>
> Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxxxx>
> ---
> +static ssize_t ath6kl_fwlog_block_read(struct file *file,
> + char __user *user_buf,
> + size_t count,
> + loff_t *ppos)
> +{
> + struct ath6kl *ar = file->private_data;
> + struct sk_buff *skb;
> + ssize_t ret_cnt;
> + size_t len = 0, not_copied;
> + char *buf;
> + int ret;
> +
> + buf = vmalloc(count);
> + if (!buf)
> + return -ENOMEM;
> +
> + spin_lock(&ar->debug.fwlog_queue.lock);
> +
> + if (skb_queue_len(&ar->debug.fwlog_queue) == 0) {
> + /* we must init under queue lock */
> + init_completion(&ar->debug.fwlog_completion);
> +
> + spin_unlock(&ar->debug.fwlog_queue.lock);
> +
> + ret = wait_for_completion_interruptible(
> + &ar->debug.fwlog_completion);
> + if (ret == -ERESTARTSYS)
> + return ret;
> +
> + spin_lock(&ar->debug.fwlog_queue.lock);
> + }
> +
> + while ((skb = __skb_dequeue(&ar->debug.fwlog_queue))) {
> + if (skb->len > count - len) {
> + /* not enough space, put skb back and leave */
> + __skb_queue_head(&ar->debug.fwlog_queue, skb);
> + break;
> + }
> +
> +
> + memcpy(buf + len, skb->data, skb->len);
> + len += skb->len;
> +
> + kfree_skb(skb);
> + }
> +
> + spin_unlock(&ar->debug.fwlog_queue.lock);
> +
> + /* FIXME: what to do if len == 0? */
> +
> + not_copied = copy_to_user(user_buf, buf, len);
> + if (not_copied != 0) {
> + ret_cnt = -EFAULT;
> + goto out;
> + }
> +
> + *ppos = *ppos + len;
Why not to use simple_read_from_buffer()?, looks like it can also
takes care of len == 0 case in the following check.
if (pos >= available || !count)
return 0;
when available (len) is 0, pos = available with
ath6kl_fwlog_block_read().
Vasanth
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