linux-kernel - Re: [PATCH 4.19 001/106] tpm: use tpm_try_get

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Date:   Wed, 9 Oct 2019 02:45:14 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Pavel Machek <pavel@...x.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Stefan Berger <stefanb@...ux.ibm.com>,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        Alexander Steffen <Alexander.Steffen@...ineon.com>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.19 001/106] tpm: use tpm_try_get_ops() in tpm-sysfs.c.

On Tue, Oct 08, 2019 at 02:51:20PM +0200, Pavel Machek wrote:
> For example this did not have any locking, and is now protected by
> 
>         get_device(&chip->dev);
> 
>         down_read(&chip->ops_sem);
> 
> . Is that intended? Is this known to fix any bugs?

It is, sysfs code can otherwise race when ops is set NULL in
class shutdown.

/Jarkko