linux-kernel - Re: [PATCH] tpm: don't destroy chip device prematurely

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Message-ID: <20161003160008.GE5722@obsidianresearch.com>
Date:   Mon, 3 Oct 2016 10:00:08 -0600
From:   Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:     "Winkler, Tomas" <tomas.winkler@...el.com>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        "tpmdd-devel@...ts.sourceforge.net" 
        <tpmdd-devel@...ts.sourceforge.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tpm: don't destroy chip device prematurely

On Mon, Oct 03, 2016 at 07:05:48AM +0000, Winkler, Tomas wrote:

> > This patch is wrong, I though the comments were clear. All entry points to find
> > the device must be deleted before we commit to shutting down the device.
> > 
> > You need to figure out some other way to solve your problem.
> 
> Please be more specific regarding flows you think will be wrong with
> this patch, you must agree that the current code is broken even w/o
> runtime pm.

No, I don't agree. Accessing dev->name is OK after the device_del.

What devicde_del does is fence off all sorts of ways to access the
device, eg sysfs files, bus registrations, etc, etc. That absolutely
must be done before calling tpm_suspend.

Jason