Re: [PATCH v2 0/2] Replace and improve "mcsafe" with copy_safe()

[Andy Lutomirski]

> On Apr 30, 2020, at 5:40 PM, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> 
> ïOn Thu, Apr 30, 2020 at 5:23 PM Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>> 
>>> But anyway, I don't hate something like "copy_to_user_fallible()"
>>> conceptually. The naming needs to be fixed, in that "user" can always
>>> take a fault, so it's the _source_ that can fault, not the "user"
>>> part.
>> 
>> I donât like this.  âuserâ already implied that basically anything can be wrong with the memory
> 
> Maybe I didn't explain.
> 
> "user" already implies faulting. We agree.
> 
> And since we by definition cannot know what the user has mapped into
> user space, *every* normal copy_to_user() has to be able to handle
> whatever faults that throws at us.
> 
> The reason I dislike "copy_to_user_fallible()" is that the user side
> already has that 'fallible".
> 
> If it's the _source_ being "fallible" (it really needs a better name -
> I will not call it just "f") then it should be "copy_f_to_user()".
> 
> That would be ok.
> 
> So "copy_f_to_user()" makes sense. But "copy_to_user_f()" does not.
> That puts the "f" on the "user", which we already know can fault.
> 
> See what I want in the name? I want the name to say which side can
> cause problems!

We are in violent agreement. Iâm moderately confident that I never suggested copy_from_user_f(). We appear to agree completely.