Date: Fri, 5 Jul 2002 19:44:36 -0700 (PDT) From: David Xu <bsddiy@yahoo.com> To: Peter Wemm <peter@wemm.org> Cc: Julian Elischer <julian@elischer.org>, current@FreeBSD.ORG Subject: Re: status of KSE merge Message-ID: <20020706024436.40687.qmail@web20907.mail.yahoo.com>
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the following patch can fix the bug, but for KSE programs, it may not be a
best solution, KSE programs signal handling is on going...
--- kern_synch.c Wed Jul 3 17:15:20 2002
+++ kern_synch.c.new Sat Jul 6 10:36:22 2002
@@ -537,8 +537,7 @@
PROC_LOCK(p);
sig = cursig(td);
if (thread_suspend_check(1)) {
- sig = EINTR;
- rval = EINTR;
+ sig = SIGSTOP;
}
mtx_lock_spin(&sched_lock);
PROC_UNLOCK(p);
-David Xu
----- Original Message -----
From: "Peter Wemm" <peter@wemm.org>
To: "Julian Elischer" <julian@elischer.org>
Cc: "FreeBSD current users" <current@FreeBSD.ORG>
Sent: Saturday, July 06, 2002 3:52 AM
Subject: Re: status of KSE merge
> Julian Elischer wrote:
>
> > At this time I have no information on any apps that fail to work (that did
> > work before KSE).
> >
> > The signal flakiness is still present but at least people can get work
> > done. I will work on this next (though signal experts are welcome to
> > try their hand as well.. (in fact any beginners who want to jump inat the
> > deep end of the pool can guarantee a near-drowning-experience by trying
> > to understand signals).
>
> Some news: syscall restart after signals is broken. This is responsible
> for a lot of the ^Z/fg problems as well as some applications failing when
> their timer signals cause IO problems.
>
> Test case:
> peter@overcee[12:49pm]~-125> cat restart.sh
> #! /tmp/44sh
> echo -n "Type something: "
> read foo
> echo "You typed: \"$foo\""
> peter@overcee[12:49pm]~-126> ./restart.sh
> Type something: foo
> You typed: "foo"
> peter@overcee[12:49pm]~-127> ktrace ./restart.sh
> Type something: ^Z
> [1] + Suspended ktrace ./restart.sh
> peter@overcee[12:49pm]~-128> fg
> ktrace ./restart.sh
> You typed: ""
> peter@overcee[12:49pm]~-129> kdump -R
> [...]
> 1091 44sh 0.000061 CALL write(0x1,0x80c4000,0x10)
> 1091 44sh 0.000029 GIO fd 1 wrote 16 bytes
> "Type something: "
> 1091 44sh 0.000198 RET write 16/0x10
> 1091 44sh 0.000187 CALL read(0,0xbfbff2f3,0x1)
> 1091 44sh 3.054434 RET read -1 errno 4 Interrupted system call
> 1091 44sh 0.000695 CALL write(0x1,0x80c4000,0xe)
> 1091 44sh 0.000025 GIO fd 1 wrote 14 bytes
> "You typed: ""
> "
> 1091 44sh 0.000254 RET write 14/0xe
> [..]
>
> The errno 4 - interrupted system call should not happen. read returns
> ERESTART internally on the signal catch, and the syscall() function in trap.c
> is supposed to back up the eip which causes the syscall to be rerun.
>
> I have not looked at the code yet. This is responsible for things like
> vipw failing after ^Z/fg (editor=vi), mergemaster failing on ^Z/fg etc.
> (it was mergemaster that tipped me off on this.)
>
> Applications that use interval timers would be suffering from this pretty
> badly.
>
> Cheers,
> -Peter
> --
> Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com
> "All of this is for nothing if we don't go to the stars" - JMS/B5
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