Re: kern/44986: "screens" gets stuck during detach

[Matthias Scheler <tron%zhadum.org.uk@localhost>]

The following reply was made to PR kern/44986; it has been noted by GNATS.

From: Matthias Scheler <tron%zhadum.org.uk@localhost>
To: christos%zoulas.com@localhost (Christos Zoulas)
Cc: NetBSD GNATS <gnats-bugs%NetBSD.org@localhost>
Subject: Re: kern/44986: "screens" gets stuck during detach
Date: Wed, 25 May 2011 23:33:37 +0100

 On 25 May 2011, at 23:25, Christos Zoulas wrote:
 
 > On May 25,  9:44pm, tron%zhadum.org.uk@localhost (Matthias Scheler) wrote:
 > -- Subject: Re: kern/44986: "screens" gets stuck during detach
 >=20
 > | On Tue, May 24, 2011 at 11:37:47AM -0400, Christos Zoulas wrote:
 > | > On May 24,  2:17pm, tron%zhadum.org.uk@localhost (Matthias Scheler) 
 > wrote:
 > | > -- Subject: Re: kern/44986: "screens" gets stuck during detach
 > | >=20
 > | > | On Tue, May 24, 2011 at 08:42:11AM -0400, Christos Zoulas wrote:
 > | > | > Backout the select changes and leave the sigsuspend changes. =
 If that fixes
 > | > | > the problem, then the problem is with select. I don't see how =
 putting the
 > | > | > code in a separate function in sys_sig.c makes a difference.
 > | > |=20
 > | > | I'm wondering how the signal mask gets restored in case of =
 select(2) now.
 > | > | There used to be code which did that. But the old signal mask is =
 simply
 > | > | copied into a property of the "lwp" structure.
 > | >=20
 > | > The same way that it is restored for sigsuspend. Look in =
 kern_sig.c
 > |=20
 > | I've reverted "sys/kern/sys_select.c" to revision 1.30 in my source =
 tree
 > | and can no longer reproduce the problem.
 >=20
 > Ok, that is curious; can you ktrace screen and if it invokes select =
 with
 > a signal mask?
 
 You mean whether it uses pselect(2)? No, it doesn't, "pselect" is not =
 mentioned anywhere in the source code.
 
        Kind regards
 
 --=20
 Matthias Scheler                           http://zhadum.org.uk/