Re: Your clang TSA patches

[Stefan Hajnoczi]

On Tue, 9 May 2023 at 03:01, Marc-André Lureau
<marcandre.lureau@gmail.com> wrote:
>
> Hi Stefan
>
> On Mon, May 8, 2023 at 6:54 PM Stefan Hajnoczi <stefanha@gmail.com> wrote:
>>
>> Hi Marc-André,
>> clang's Thread Safety Analysis is being used more in the QEMU block
>> layer and a few limitations have been hit:
>> 1. Mutexes that are struct fields are not supported (only global mutexes 
>> work).
>> 2. Analysis does not extend across function pointers. See
>> GRAPH_RDLOCK_PTR for a workaround that is currently used.
>>
>> (There was a third limitation that I don't remember. Maybe Kevin remembers.)
>>
>> I heard you had clang or LLVM patches in that past that improve TSA.
>> Did your patches address these things? Any idea how hard it is to fix
>> these limitations?
>
>
>
> I don't remember much about that work, I didn't spend that much time on it, 
> and it was 5y ago already!
>
> My WIP branch is still available: 
> https://github.com/elmarco/clang/commits/qemu-ta
>
> it seems I was trying to modify clang to support TSA annotations on typedef 
> and function pointers, and warn on unmatching. I have no idea if this is 
> still relevant. I remember dropping the effort at that time because of lack 
> of interest or help in both projects.

Thanks! The changes seem small enough that it may be possible to get
them merged without a major time commitment.

It seems the function pointer analysis limitation still exists after
these 5 years :).

Stefan