Re: Nasty 2.6 sendfile() bug / regression; affects vsftpd

From: Linus Torvalds
Date: Mon Apr 19 2004 - 00:32:03 EST

On Mon, 19 Apr 2004, Jamie Lokier wrote:
> Is there a reason why put_user() supports 1/2/4/8 bytes and get_user()
> supports only 1/2/4 bytes?

It's a bit more complicated to do get_user, mainly because we use a 64-bit
value to pass the data around already on x86 - the "real data" in %eax,
and the error code in %edx. So you'd need to have a slightly different
calling convention for the 8-byte case, so it was more than just
"duplicate the other cases".

I agree that it's an ugly special case. get/put_user should really accept
all the normal cases, and that includes 'u64'.

Not a lot of code cares, though, so for now we've just had the special
case. You are the first one to notice, I think.

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