Re: kern/50430: syscall_disestablish() can remove active syscalls

[Masao Uebayashi <uebayasi%gmail.com@localhost>]

The following reply was made to PR kern/50430; it has been noted by GNATS.

From: Masao Uebayashi <uebayasi%gmail.com@localhost>
To: Christos Zoulas <christos%zoulas.com@localhost>
Cc: gnats-bugs%netbsd.org@localhost, kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, 
	netbsd-bugs%netbsd.org@localhost, Paul Goyette <paul%whooppee.com@localhost>
Subject: Re: kern/50430: syscall_disestablish() can remove active syscalls
Date: Mon, 16 Nov 2015 17:08:42 +0900

 On Mon, Nov 16, 2015 at 6:45 AM, Christos Zoulas <christos%zoulas.com@localhost> wrote:
 > On Nov 15,  8:25pm, mrg%eterna.com.au@localhost (matthew green) wrote:
 > -- Subject: re: kern/50430: syscall_disestablish() can remove active syscalls
 >
 > |  until bug is fixed, can we disable the autounload?
 >
 > Sure, that sounds prudent. It is difficult to fix properly. One way to do
 > this would be to mark all lwps that have used compat syscalls with a bit
 > depending on the module they have used, and refuse to unload the module
 > until the lwp is gone.
 >
 > - when load a module that has compat syscalls, assign to it a bit.
 > - mark a flags field of all syscalls that were loaded with that module
 >   with that bit.
 > - or the lwp flags with the syscall flags on each syscall.
 > - when it is time to unload check that no lwp has that bit in the flags set.
 > - instead of keeping l_sysent, keep l_sysmodflags or something.
 
 What happens if signal handler does longjmp(3) and interrupted syscall
 never returns?