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Date:   Fri, 8 Nov 2019 18:27:49 -0800
From:   Eric Biggers <ebiggers@kernel.org>
To:     Tero Kristo <t-kristo@ti.com>
Cc:     Herbert Xu <herbert@gondor.apana.org.au>,
        Gilad Ben-Yossef <gilad@benyossef.com>,
        David Miller <davem@davemloft.net>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        linux-omap@vger.kernel.org,
        Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 09/10] crypto: add timeout to crypto_wait_req
Message-ID: <20191109022749.GB9739@sol.localdomain>
Mail-Followup-To: Tero Kristo <t-kristo@ti.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Gilad Ben-Yossef <gilad@benyossef.com>,
        David Miller <davem@davemloft.net>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        linux-omap@vger.kernel.org,
        Linux ARM <linux-arm-kernel@lists.infradead.org>
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 <20191108022759.GB1140@sol.localdomain>
 <d55c0182-5fb0-2ef9-f056-54b396fb0026@ti.com>
 <20191108091608.i5fxt2vu2nwrybgn@gondor.apana.org.au>
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On Fri, Nov 08, 2019 at 11:22:48AM +0200, Tero Kristo wrote:
> On 08/11/2019 11:16, Herbert Xu wrote:
> > On Fri, Nov 08, 2019 at 09:40:57AM +0200, Tero Kristo wrote:
> > > 
> > > The problem is not detecting a hung task, the problem is determining what
> > > caused the hang. Personally I don't care if the system dies if a crypto
> > > accelerator self test has failed, as long as I get reported about the exact
> > > nature of the failure. The failures are expected to happen only in
> > > development phase of a crypto driver.
> > > 
> > > With the timeout patch in place, I get reported what exact crypto test case
> > > failed and I can focus my debug efforts on that one.
> > 
> > If that's all you need then how about just making the wait killable?
> 
> Yeah, that would be an alternative.
> 

I don't see how making crypto_wait_req killable would be any better than adding
a timeout, since in both cases the crypto operation would still be proceeding in
the background while things are being freed.

Would it help if the crypto self-tests printed a pr_debug() message when
starting each test vector?  These wouldn't be shown by default, but it would be
possible to enable them using dynamic-debug or by adding '#define DEBUG' to the
top of the source file.

- Eric