linux-kernel - Re: [PATCH 1/8] tpm: block messages while suspended

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Message-ID: <20190617225134.GA30762@ziepe.ca>
Date:   Mon, 17 Jun 2019 19:51:34 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Peter Huewe <peterhuewe@....de>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Andrey Pronin <apronin@...omium.org>,
        linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-integrity@...r.kernel.org, devicetree@...r.kernel.org,
        Duncan Laurie <dlaurie@...omium.org>,
        Guenter Roeck <groeck@...omium.org>
Subject: Re: [PATCH 1/8] tpm: block messages while suspended

On Fri, Jun 14, 2019 at 11:12:36AM -0700, Stephen Boyd wrote:
> Quoting Jason Gunthorpe (2019-06-13 16:26:13)
> > On Thu, Jun 13, 2019 at 11:09:24AM -0700, Stephen Boyd wrote:
> > > From: Andrey Pronin <apronin@...omium.org>
> > > 
> > > Other drivers or userspace may initiate sending a message to the tpm
> > > while the device itself and the controller of the bus it is on are
> > > suspended. That may break the bus driver logic.
> > > Block sending messages while the device is suspended.
> > > 
> > > Signed-off-by: Andrey Pronin <apronin@...omium.org>
> > > Signed-off-by: Stephen Boyd <swboyd@...omium.org>
> > > 
> > > I don't think this was ever posted before.
> > 
> > Use a real lock.
> > 
> 
> To make sure the bit is tested under a lock so that suspend/resume can't
> update the bit in parallel?

No, just use a real lock, don't make locks out of test bit/set bit

Jason