Re: calling context when writing to tty_driver

David McIlwraith
2002-10-01T11:28:04Z

Spinlocks *could* be used in place, if this is the case. Having not examined
the code, I don't know the implementation specifics.

----- Original Message -----
From: "Martin Diehl" <lists@mdiehl.de>
To: "David McIlwraith" <quack@bigpond.net.au>
Cc: "Martin Diehl" <lists@mdiehl.de>; <linux-kernel@vger.kernel.org>
Sent: Tuesday, October 01, 2002 9:28 PM
Subject: Re: calling context when writing to tty_driver

> On Tue, 1 Oct 2002, David McIlwraith wrote:
>
> > Semaphores may sleep - therefore, they cannot be used from a 'non-sleep'
> > context.
>
> Yes, sure. Sorry if I wasn't clear enough - the point is whether those
> tty_driver write/write_room() calls are allowed to sleep or not. If yes,
> the usbserial implementation is right and it is impossible to do further
> writing directly from write_wakeup() callback (which would be really bad
> IMHO) - if not, usbserial needs to avoid the down() somehow.
>
> Martin
>
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