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From: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Peter Huewe <peterhuewe@gmx.de>,
	Marcel Selhorst <tpmdd@selhorst.net>,
	"moderated list:TPM DEVICE DRIVER" 
	<tpmdd-devel@lists.sourceforge.net>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] tpm: fix crash in tpm_tis deinitialization
Date: Wed, 13 Apr 2016 11:04:26 -0600	[thread overview]
Message-ID: <20160413170426.GA28411@obsidianresearch.com> (raw)
In-Reply-To: <20160413065805.GB6986@intel.com>

On Wed, Apr 13, 2016 at 09:58:05AM +0300, Jarkko Sakkinen wrote:
> > > It prevents everything including the kernel from issuing a command
> >                          ^^^^^^^^^^^^^^^^^^^^
> > 
> > That lock is not used to exclude kernel access. Read lock is only taken
> > for the user space device in tpm-dev.c.
> 
> My bad. For the in-kernel API it is taken through tpm_find_get().

Right. At this point any thing that can run in-kernel concurrently
with the write exclusion is a kernel bug. Those places will need to
grab the read side of the lock.

Jason

      reply	other threads:[~2016-04-13 17:04 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-11 16:05 Jarkko Sakkinen
2016-04-11 17:40 ` Jason Gunthorpe
2016-04-12  4:26   ` Jarkko Sakkinen
2016-04-12 17:26     ` Jason Gunthorpe
2016-04-13  6:16       ` Jarkko Sakkinen
2016-04-13  6:58         ` Jarkko Sakkinen
2016-04-13 17:04           ` Jason Gunthorpe [this message]

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