From: Paul Fulghum <paulkf@microgate.com>
To: franck.bui-huu@innova-card.com
Cc: linux-kernel@vger.kernel.org, linux-os@analogic.com,
pmarques@grupopie.com
Subject: Re: [TTY] 2 points seems strange to me.
Date: Fri, 18 Feb 2005 10:41:01 -0600 [thread overview]
Message-ID: <42161A9D.1080406@microgate.com> (raw)
In-Reply-To: <421617D3.4080207@innova-card.com>
Franck Bui-Huu wrote:
> I was looking at driver for 8250 in 8250.c file and at the end
> of "receive_chars" interrupt handler, it calls "tty_flip_buffer_push"
> even if "tty->low_latency" is set since no such test is done before
> the call...
Yes this is a known problem. In the case of SMP kernel
and low_latency, and 8250.c, this causes a dead lock. This has
resurfaced again and again for many months from
different sources.
There is disagreement on what code is
in error and what should be fixed. So it stays broken.
> I was also wondering why not always calling "schedule_delayed_work"
> whatever the state of "tty->latency"?
If low_latency is set and you are not calling
from interrupt, then calling work directly speeds processing.
I submitted a patch that forced schedule_delayed_work
if in interrupt context to avoid this problem. It was rejected.
--
Paul Fulghum
Microgate Systems, Ltd.
next prev parent reply other threads:[~2005-02-18 16:42 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-17 17:51 Problems with dma_mmap_writecombine on mach-pxa Frank Buss
2005-02-17 18:12 ` Russell King
2005-02-17 19:14 ` Frank Buss
2005-02-17 19:58 ` Russell King
2005-02-18 9:30 ` [TTY] 2 points seems strange to me Franck Bui-Huu
2005-02-18 14:58 ` Paul Fulghum
2005-02-18 15:08 ` Paulo Marques
2005-02-18 15:15 ` Paul Fulghum
2005-02-18 15:24 ` Paulo Marques
2005-02-18 15:24 ` linux-os
2005-02-18 15:27 ` Paulo Marques
2005-02-18 16:14 ` Franck Bui-Huu
2005-02-18 15:19 ` linux-os
2005-02-18 16:29 ` Franck Bui-Huu
2005-02-18 16:41 ` Paul Fulghum [this message]
2005-02-18 18:07 ` Problems with dma_mmap_writecombine on mach-pxa Frank Buss
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