On 02/01, Stas Sergeev wrote: > > 01.02.2016 20:09, Oleg Nesterov пишет: > >OK, I didn't notice you modified save_altstack_ex() to use ->sas_ss_flags instead > >of sas_ss_flags()... still doesn't look right, in this case restore_altstack() will > >not restore sas_ss_size/sas_ss_sp and they can be changed by signal handler. > How? > Trying to change them in a sighandler with sigaltstack() > will get EPERM. Only if on_sig_stack() and this is not true if we change the stack. > >Anyway, whatever I missed I agree with Andy, SS_FORCE looks simpler and better to me. > > But perhaps you missed the most important thing, that > it is not possible to change the altstack in sighandler - you'll > get EPERM, even with my patch. See above. > But with SS_FORCE this is > exactly not the case. Yes, and SS_FORCE means "I know what I do", looks very simple. > Also it would be interesting to know what do you think about > just removing the EPERM check instead of this all. 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. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
