Re: Copy_to_user and copy_from_user

["Ramesh Sudini" <rameshred@hotmail.com>]

Then, how do I make sure that all the data I wanted to be copied is infact 
copied?? What are the scenarios where copy_to/from_user could fail and how 
can I avoid it.

Thanks
-Ramesh


>
>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
>>

_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today - it's FREE! 
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/