Re: [PATCH 4/4] sigaltstack: allow disabling and re-enabling sas within sighandler

[Stas Sergeev]

01.02.2016 21:04, Oleg Nesterov ÐÐÑÐÑ:
> Yes, and SS_FORCE means "I know what I do", looks very simple.
But to me its not because I don't know what to do with
uc_stack after SS_FORCE is applied.

> I won't argue, but to me it would be better to keep this EPERM if !force.
> Just because we should avoid the incompatible changes if possible.
Ok then. Lets implement SS_FORCE.
What semantic should it have wrt uc_stack?

sigaltstack(SS_DISABLE | SS_FORCE);
swapcontext();
sigaltstack(set up new_sas);
rt_sigreturn();

What's at the end? Do we want a surprise for the user
that he's new_sas got ignored?