From: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
To: Lou Langholtz <ldl@chpc.utah.edu>
Cc: Linux/PPC Development <linuxppc-dev@lists.linuxppc.org>
Subject: Re: [Fwd: Bug: 2.2.12 still hangs PPC after some PPP activity]
Date: Wed, 29 Sep 1999 09:39:01 +0200 (MET DST) [thread overview]
Message-ID: <Pine.GSO.4.10.9909290937380.328-100000@begonia.sonytel.be> (raw)
In-Reply-To: <37F1C0A3.B9F25580@chpc.utah.edu>
Hi Lou,
> > > What might happen if a driver does:
> >
> > point A
> >
> > > save_flags(old_flags);
> > > cli();
> > > restore_flags(old_flags);
>
> point A2?
>
> > > save_flags(new_flags);
> > > cli();
> > > restore_flags(new_flags);
> >
> > point B
> >
> > > /* can't we be interupted here? Assume yes, if so */
> > > restore_flags(old_flags);
> >
> > point C
point A == point A2 == point B == point C
> > > . . .Opinions??? Please clue me in anyway... this stuff's a kick! :-)
> >
> > The interrupt mask register has the same contents at points A, B and C. Hence,
> > if we could be interrupt a point A, we can be interrupt at points B and C. . . .
>
> Looking in macserial.c's rs_write() function it can call transmit_chars(info) at
> point B which would seem to me to be able to be a point at which the interupt mask
> register could change. No? I have to admit I'm only now reading the various docs
> on kernel locks. So I just email'd you hoping you'd give me another hint ;-)
I don't know how the serial port hardware has to be programmed. But if
transmit_chars() must be called with interrupts disabled, it's indeed a bug.
Greetings,
Geert
--
Geert Uytterhoeven ----------------- Sony Suprastructure Center Europe (SUPC-E)
Geert.Uytterhoeven@sonycom.com ------------------- Sint Stevens Woluwestraat 55
Phone +32-2-7248648 Fax +32-2-7262686 ---------------- B-1130 Brussels, Belgium
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
next parent reply other threads:[~1999-09-29 7:39 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <37F1C0A3.B9F25580@chpc.utah.edu>
1999-09-29 7:39 ` Geert Uytterhoeven [this message]
[not found] <37F1AD4B.585E99AB@chpc.utah.edu>
1999-09-29 7:11 ` [Fwd: Bug: 2.2.12 still hangs PPC after some PPP activity] Geert Uytterhoeven
1999-09-29 7:16 ` Takashi Oe
1999-09-29 7:40 ` Geert Uytterhoeven
1999-09-29 9:13 ` Benjamin Herrenschmidt
1999-09-30 0:46 ` Takashi Oe
1999-09-30 8:50 ` Benjamin Herrenschmidt
1999-09-30 16:21 ` Takashi Oe
1999-09-30 16:35 ` Benjamin Herrenschmidt
1999-10-12 7:20 ` Lou Langholtz
1999-09-29 16:44 ` Lou Langholtz
1999-09-29 17:02 ` Benjamin Herrenschmidt
1999-09-29 18:08 ` Lou Langholtz
1999-09-29 18:46 ` Lou Langholtz
1999-09-29 20:00 ` Lou Langholtz
1999-09-30 1:14 ` Takashi Oe
1999-09-30 5:33 ` Geert Uytterhoeven
1999-10-01 13:26 ` Franz Sirl
1999-10-01 13:46 ` Alvin Brattli
[not found] ` <Pine.OSF.3.96.991001153658.16772E-100000@mitra.phys.uit.no >
1999-10-01 14:08 ` Franz Sirl
1999-10-01 16:14 ` Lou Langholtz
1999-09-10 16:51 Lou Langholtz
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