Re: [PATCH v4 04/10] tpm: Get rid of module locking

["Stefan Berger" <stefanb-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>]

[-- Attachment #1.1: Type: text/plain, Size: 2379 bytes --]

Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> wrote on 02/29/2016 
03:35:50 PM:


> On Mon, Feb 29, 2016 at 12:29:50PM -0500, Stefan Berger wrote:
> > Now that the tpm core has strong locking around 'ops' it is possible
> > to remove a TPM driver, module and all, even while user space still
> > has things like /dev/tpmX open. For consistency and simplicity, drop
> > the module locking entirely.
> 
> I don't understand why the user visible behavior of /dev/tpmX should
> be changed if there are no life and death reasons to do it. Do you
> think that this patch is absolutely crucial for the feature
> implemented?

This changes the module counter on the hardware / backend driver and not 
other user visible behavior from what I can tell. It's certainly/hopefully 
not a life-and-death thing, though I am wondering whether it's be applied 
sooner or later anyway for cleanup reasons following the preceding patch 
providing 'strong locking'.

   Stefan

> 
> /Jarkko
> 
> > Signed-off-by: Stefan Berger <stefanb-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
> > ---
> >  drivers/char/tpm/tpm-chip.c | 6 +-----
> >  1 file changed, 1 insertion(+), 5 deletions(-)
> > 
> > diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> > index 1ae30f2..8f4b5f2 100644
> > --- a/drivers/char/tpm/tpm-chip.c
> > +++ b/drivers/char/tpm/tpm-chip.c
> > @@ -57,9 +57,6 @@ int tpm_try_get_ops(struct tpm_chip *chip)
> >     if (!chip->ops)
> >        goto out_lock;
> > 
> > -   if (!try_module_get(chip->dev.parent->driver->owner))
> > -      goto out_lock;
> > -
> >     return 0;
> >  out_lock:
> >     up_read(&chip->ops_sem);
> > @@ -77,7 +74,6 @@ EXPORT_SYMBOL_GPL(tpm_try_get_ops);
> >   */
> >  void tpm_put_ops(struct tpm_chip *chip)
> >  {
> > -   module_put(chip->dev.parent->driver->owner);
> >     up_read(&chip->ops_sem);
> >     put_device(&chip->dev);
> >  }
> > @@ -183,7 +179,7 @@ struct tpm_chip *tpmm_chip_alloc(struct device 
*dev,
> >        goto out;
> > 
> >     cdev_init(&chip->cdev, &tpm_fops);
> > -   chip->cdev.owner = dev->driver->owner;
> > +   chip->cdev.owner = THIS_MODULE;
> >     chip->cdev.kobj.parent = &chip->dev.kobj;
> > 
> >     rc = devm_add_action(dev, (void (*)(void *)) put_device, 
&chip->dev);
> > -- 
> > 2.4.3
> > 
> 



[-- Attachment #1.2: Type: text/html, Size: 3212 bytes --]

[-- Attachment #2: Type: text/plain, Size: 413 bytes --]

------------------------------------------------------------------------------
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140

[-- Attachment #3: Type: text/plain, Size: 192 bytes --]

_______________________________________________
tpmdd-devel mailing list
tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
https://lists.sourceforge.net/lists/listinfo/tpmdd-devel