linux-kernel - Re: Using "Asynchronous Notifications" within an interrupt handler

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Date:	Fri, 6 Oct 2006 12:10:09 -0500
From:	"Madhu Saravana Sibi Govindan" <ssshayagriva@...il.com>
To:	"Jan Engelhardt" <jengelh@...ux01.gwdg.de>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Using "Asynchronous Notifications" within an interrupt handler

Thanks for the information.

I have another quick question: my device driver can expect up to 4
different interrupts (from 4 hardware devices). Can I send a posix
real-time signal (SIGRTMIN) using the kill_async interface and expect
the kernel to queue these signals for delievery to the sleeping
process? (Because if I use SIGIO it is possible that an incoming
interrupt is lost because the kernel doesn't queue up normal signals,
right?).

Thanks,
G.Sibi

On 10/6/06, Jan Engelhardt <jengelh@...ux01.gwdg.de> wrote:
> >
> > My question is: is it safe to use the asynchronous notification
> > mechanism within an interrupt handler? I see that this call acquires a
> > bunch of locks before sending the signal to the process. Would this
> > cause any deadlocking situations? Or should I resort to the top and
> > bottom half approach for interrupt handling and handle the
> > notification in the bottom half?
>
> It may be possible - I have an old driver for custom hardware lying
> around here, and it does this in the irq handler:
>
> kill_fasync(&global.fasync_ptr, SIGIO, POLL_IN);
>
>
>
>         -`J'
> --
>
-
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