Re: [Qemu-devel] [RFC PATCH 0/5] Scoped locks using attribute((cleanup))

[Paolo Bonzini]

On 11/12/2017 15:11, Eric Blake wrote:
> I don't know if there is a way to make gcc insert stack-unwind
> directives that are honored across longjmp (I know C++ does it for
> exceptions; so there may be a way, and I just don't know it).

Probably -fexceptions.

Paolo

> Conversely, I do know that pthread_cleanup_push/pop, which does
> something similar, is permitted by POSIX to NOT work across longjmp:
> 
>        Calling longjmp(3) (siglongjmp(3)) produces undefined  results
> if  any
>        call  has  been made to pthread_cleanup_push() or
> pthread_cleanup_pop()
>        without the matching call of the pair since the jump buffer was
> filled
>        by   setjmp(3)  (sigsetjmp(3)).   Likewise,  calling  longjmp(3)
> (sig‐
>        longjmp(3)) from inside a clean-up handler produces  undefined
> results
>        unless  the  jump  buffer  was  also filled by setjmp(3)
> (sigsetjmp(3))
>        inside the handler.

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