On 02/06/2012 11:06 AM, Vasanthakumar Thiagarajan wrote:
> 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>
[...]
>> + 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().
I actually used simple_read_from_buffer() first, but the problem is that
it assumes that there's just one buffer from which the data is copied.
But in this case there can be multiple buffers from which I copy data.
Ok, that was a bit confusing, let's try to explain a bit differently :)
If 'ppos > 0' (for example during the second function call)
simple_read_from_buffer() will try to copy from 'user_buf + ppos' but I
would want to copy from 'user_buf'.
Kalle
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