Re: Copy_to_user and copy_from_user

[Kernoulas]

No you cannot call it until all data has been copied. 
copy_{to,from}_user fails when a fault happens during the copy process. 
So you simply cannot try again... It will fault again.
Well, not 100% true. An other running thread (same mm with the process 
which copies data) can "fix" the faulty adress space. Bad thread....

Ramesh Sudini wrote:
> Hi,
>
> If copy_from_user returns non zero value, then I do not see any 
> driver(for example PPP) try to copy the remaining data. It treats it as 
> an error scenario.
>
> Why is this? Shouldnt it have a while loop and attempt to copy_from_user 
> till all the data is copied??
>
> I am writing a driver and trying to understand what needs to be done in 
> case it returns a non-zero value? I have huge amount of data to be 
> copied from user space Ex: 3000byte messages.
>
> Can somebody suggest me what is the best I could do...(Please cc me 
> personally with your response)
>
> Thanks
> Ramesh
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