linux-kernel - Re: Broken pci_block_user_cfg

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]

Date:	Mon, 29 Aug 2011 22:18:58 +0300
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Jan Kiszka <jan.kiszka@...mens.com>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Brian King <brking@...ibm.com>,
	"James E.J. Bottomley" <JBottomley@...allels.com>,
	"Hans J. Koch" <hjk@...sjkoch.de>,
	Greg Kroah-Hartman <gregkh@...e.de>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
	kvm@...r.kernel.org
Subject: Re: Broken pci_block_user_cfg_access interface

On Mon, Aug 29, 2011 at 08:47:07PM +0200, Jan Kiszka wrote:
> On 2011-08-29 17:42, Jan Kiszka wrote:
> > I still don't get what prevents converting ipr to allow plain mutex
> > synchronization. My vision is:
> >  - push reset-on-error of ipr into workqueue (or threaded IRQ?)
> 
> I'm starting to like your proposal: I had a look at ipr, but it turned
> out to be anything but trivial to convert that driver. It runs its
> complete state machine under spin_lock_irq, and the functions calling
> pci_block/unblock_user_cfg_access are deep inside this thing. I have no
> hardware to test whatever change, and I feel a bit uncomfortable asking
> Brian to redesign his driver that massively.
> 
> So back to your idea: I would generalize pci_block_user_cfg_access to
> pci_block_cfg_access. It should fail when some other site already holds
> the access lock, but it should remain non-blocking - for the sake of ipr.

It would be easy to have blocking and non-blocking variants.

But
- I have no idea whether supporting sysfs config/reset access
  while ipr is active makes any sense - I know we need it for uio.
- reset while uio handles interrupt needs to block, not fail I think


> We should still provide generic pci-2.3 IRQ masking services, but that
> could be done in a second step. I could have a look at this.
> 
> Jan
> 
> -- 
> Siemens AG, Corporate Technology, CT T DE IT 1
> Corporate Competence Center Embedded Linux
--
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/