linux-kernel - Re: [PATCH 2/2] tpm_tis: Clean up the force=1 module parameter

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20151201173549.GB691@obsidianresearch.com>
Date:	Tue, 1 Dec 2015 10:35:49 -0700
From:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
Cc:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
	tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	Martin Wilck <Martin.Wilck@...fujitsu.com>,
	Peter Huewe <peterhuewe@....de>
Subject: Re: [PATCH 2/2] tpm_tis: Clean up the force=1 module parameter

On Tue, Dec 01, 2015 at 08:28:35AM +0100, Uwe Kleine-König wrote:
> On Mon, Nov 30, 2015 at 12:27:12PM -0700, Jason Gunthorpe wrote:
> > The TPM core has long assumed that every device has a driver attached,
> > however b8b2c7d845d5 ("base/platform: assert that dev_pm_domain callbacks are
> > called unconditionally") breaks that assumption.
> 
> Maybe it's worth to point out that b8b2c7d845d5 didn't break it on
> purpose and is fixed accordingly. Still the assumption isn't valid, but
> works in practise.

Purposeful or not, it is the source of the bug this patch is
fixing.. I'm happy with any language, proposal?
> > +        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +        if (res == NULL) {
> 
> indention problems here.

Woops, forgot to run check patch..

> > +	if (res)
> > +		tpm_info.irq = res->start;
> > +	else {
> 
> If one branch of an if/else has braces, all of them should.

Is that a thing now? Surprised checkpatch doesn't complain.

> >  static bool force;
> > +#ifdef CONFIG_X86
> >  module_param(force, bool, 0444);
> >  MODULE_PARM_DESC(force, "Force device probe rather than using ACPI entry");
> > +#endif
> 
> Is this added ifdef intended to be in this commit?

Yes, upon auditing all this it is clear the values we have are
hard-wired to x86, so this will never work on another platform.

I'm happy to put that in another patch.

> > -err_init:
> > -	platform_device_unregister(pdev);
> > -err_dev:
> > -	platform_driver_unregister(&tis_drv);
> > +out4:
> > +#ifdef CONFIG_ACPI
> > +	acpi_bus_unregister_driver(&tis_acpi_driver);
> > +out3:
> > +#endif
> > +	pnp_unregister_driver(&tis_pnp_driver);
> > +out2:
> > +	platform_device_unregister(force_pdev);
> > +out1:
> 
> Might be a matter of taste, but having nicer names for the error labels
> makes review easier. For example I would have called "out3"
> "err_register_acpi" instead. Then you can easily verify that it's placed
> right in the error path being directly after
> acpi_bus_unregister_driver.

The downside is it is harder to review the goto sites because there is
no longer much logic to their ordering, but sure, names seem a bit
more common in tpm.

> Also all kind of strange things happen if you later need to add a label
> between out2 and out3. drivers/scsi/hpsa.c for example used "clean2_5"
> in a similar situation.

Yes, it isn't so bad to do that.

Jason
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/