From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Grant Edwards <grant.b.edwards@gmail.com>
Cc: linux-serial@vger.kernel.org
Subject: Re: tty_flip_buffer() from atomic context when low_latency==1
Date: Fri, 19 Aug 2011 21:24:16 +0100 [thread overview]
Message-ID: <20110819212416.6f626852@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <j2med6$q2r$1@dough.gmane.org>
> But, many drivers appear to call tty_flip_buffer_push() from an atomic
> context. If that is done with tty->low_latency==1 it turns into a call
> to flush_to_ldisc(), which then calls disc->ops->receive_buf(), which
> must not be called from an atomic context.
It's covered under "So don't do that then".
> Is the low_latency flag being forced to 0 somewhere behind the scenes
> when tty_flip_buffer_push() is being called from an atomic context?
No. The driver authors are assumed to have a modicum of competence and if
they don't usually a shower of lock debug messages enlightens
appropriately.
Alan
next prev parent reply other threads:[~2011-08-19 20:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-19 19:43 tty_flip_buffer() from atomic context when low_latency==1 Grant Edwards
2011-08-19 20:24 ` Alan Cox [this message]
2011-08-19 20:44 ` Grant Edwards
2011-08-19 21:06 ` Alan Cox
2011-08-19 21:24 ` Grant Edwards
2011-08-19 21:31 ` Alan Cox
2011-08-19 21:52 ` Grant Edwards
2011-08-19 22:53 ` Alan Cox
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