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Groups > linux.kernel > #1495202
| From | Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] tpm: don't destroy chip device prematurely |
| Date | 2016-10-04 07:30 +0200 |
| Message-ID | <soqsF-6wU-1@gated-at.bofh.it> (permalink) |
| References | (1 earlier) <snM2e-5xP-5@gated-at.bofh.it> <snMbU-5Br-19@gated-at.bofh.it> <snWuB-3G8-11@gated-at.bofh.it> <so5xT-Vq-1@gated-at.bofh.it> <soaQV-4YM-9@gated-at.bofh.it> |
| Organization | Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo |
On Mon, Oct 03, 2016 at 03:48:36PM +0300, Jarkko Sakkinen wrote:
> On Mon, Oct 03, 2016 at 07:05:48AM +0000, Winkler, Tomas wrote:
> >
> > > On Sun, Oct 02, 2016 at 01:24:55PM +0300, Jarkko Sakkinen wrote:
> > > > On Sun, Oct 02, 2016 at 01:17:55PM +0300, Jarkko Sakkinen wrote:
> > > > > On Sun, Oct 02, 2016 at 10:39:31AM +0300, Tomas Winkler wrote:
> > > > > > In tpm_del_char_device device_del is called prior to tpm2_shutdown
> > > > > > where it is still used.
> > > > > >
> > > > > > Fortunately, so far chip->dev was used only for printouts int
> > > > > > tpm2_shutdown flow, hence system didn't crash. But with the
> > > > > > introduction of runtime power management it will result in
> > > > > > shutting down the parent device while it still in use.
> > > > > >
> > > > > > Fixes: 20e0152393b41 ("tpm: fix crash in tpm_tis
> > > > > > deinitialization")
> > > > > > Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
> > > > >
> > > > > Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > > > > Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > > >
> > > > Applied.
> > >
> > > 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.
>
> Make the driver uncallable first. The worst race that can happen is that
> open("/dev/tpm0", ...) returns -EPIPE. I do not consider this fatal at
> all.
No responses for this reasonable proposal so I'll show what I mean:
/* Make the driver uncallable. */
down_write(&chip->ops_sem);
if (chip->flags & TPM_CHIP_FLAG_TPM2)
tpm2_shutdown(chip, TPM2_SU_CLEAR);
chip->ops = NULL;
up_write(&chip->ops_sem);
cdev_del(&chip->cdev);
device_del(&chip->dev);
/* Make the chip unavailable. */
mutex_lock(&idr_lock);
idr_replace(&dev_nums_idr, NULL, chip->dev_num);
mutex_unlock(&idr_lock);
The worst thing that can happen is -EPIPE.
/Jarkko
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[PATCH] tpm: don't destroy chip device prematurely Tomas Winkler <tomas.winkler@intel.com> - 2016-10-02 09:50 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2016-10-02 12:20 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2016-10-02 12:30 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-02 23:30 +0200
RE: [PATCH] tpm: don't destroy chip device prematurely "Winkler, Tomas" <tomas.winkler@intel.com> - 2016-10-03 09:10 +0200
RE: [PATCH] tpm: don't destroy chip device prematurely "Winkler, Tomas" <tomas.winkler@intel.com> - 2016-10-03 09:40 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2016-10-03 14:50 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-03 18:10 +0200
RE: [PATCH] tpm: don't destroy chip device prematurely "Winkler, Tomas" <tomas.winkler@intel.com> - 2016-10-03 19:40 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2016-10-03 14:50 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2016-10-04 07:30 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-04 18:50 +0200
RE: [PATCH] tpm: don't destroy chip device prematurely "Winkler, Tomas" <tomas.winkler@intel.com> - 2016-10-05 00:00 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-05 01:20 +0200
RE: [PATCH] tpm: don't destroy chip device prematurely "Winkler, Tomas" <tomas.winkler@intel.com> - 2016-10-05 09:50 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2016-10-05 17:20 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-05 18:40 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-05 19:20 +0200
RE: [PATCH] tpm: don't destroy chip device prematurely "Winkler, Tomas" <tomas.winkler@intel.com> - 2016-10-05 22:10 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-05 23:20 +0200
RE: [PATCH] tpm: don't destroy chip device prematurely "Winkler, Tomas" <tomas.winkler@intel.com> - 2016-10-06 02:50 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-06 04:10 +0200
RE: [PATCH] tpm: don't destroy chip device prematurely "Winkler, Tomas" <tomas.winkler@intel.com> - 2016-10-07 16:30 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-07 21:20 +0200
RE: [PATCH] tpm: don't destroy chip device prematurely "Winkler, Tomas" <tomas.winkler@intel.com> - 2016-10-07 22:20 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2016-10-08 12:50 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2016-10-05 12:10 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-05 18:30 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2016-10-06 13:30 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-06 18:30 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2016-10-06 18:50 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> - 2016-10-05 12:10 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-03 18:10 +0200
RE: [PATCH] tpm: don't destroy chip device prematurely "Winkler, Tomas" <tomas.winkler@intel.com> - 2016-10-03 19:20 +0200
Re: [PATCH] tpm: don't destroy chip device prematurely Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2016-10-03 19:40 +0200
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