linux-kernel - Re: [RFC PATCH 0/1] dm-crypt excessive overhead

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Message-ID: <alpine.LRH.2.02.2006201535280.24999@file01.intranet.prod.int.rdu2.redhat.com>
Date:   Sat, 20 Jun 2020 15:36:21 -0400 (EDT)
From:   Mikulas Patocka <mpatocka@...hat.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>
cc:     Ignat Korchagin <ignat@...udflare.com>,
        "David S. Miller" <davem@...emloft.net>,
        Mike Snitzer <snitzer@...hat.com>, agk@...hat.com,
        dm-devel@...hat.com, dm-crypt@...ut.de,
        linux-kernel@...r.kernel.org, kernel-team@...udflare.com
Subject: Re: [RFC PATCH 0/1] dm-crypt excessive overhead



On Sat, 20 Jun 2020, Herbert Xu wrote:

> On Fri, Jun 19, 2020 at 02:39:39PM -0400, Mikulas Patocka wrote:
> >
> > I'm looking at this and I'd like to know why does the crypto API fail in 
> > hard-irq context and why does it work in tasklet context. What's the exact 
> > reason behind this?
> 
> You're not supposed to do any real work in IRQ handlers.  All
> the substantial work should be postponed to softirq context.

I see.

BTW - should it also warn if it is running in a process context with 
interrupts disabled?

Mikulas

> Why do you need to do work in hard IRQ context?
> 
> Cheers,
> -- 
> Email: Herbert Xu <herbert@...dor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
>