netdev - Re: network devices don't handle pci_dma_mapping

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:	Thu, 7 Dec 2006 11:55:22 +0530
From:	"Amit S. Kale" <amitkale@...syssoft.com>
To:	Stephen Hemminger <shemminger@...l.org>
Cc:	David Miller <davem@...emloft.net>, muli@...ibm.com,
	jeff@...zik.org, amitkale@...xen.com, netdev@...r.kernel.org,
	brazilnut@...ibm.com, netxenproj@...syssoft.com, rob@...xen.com,
	romieu@...zoreil.com, sanjeev@...xen.com, wendyx@...ibm.com
Subject: Re: network devices don't handle pci_dma_mapping_error()'s

We can let a driver handle dma mapping errors using these->

1.Reduce the size of a receive ring. This will free some possibly remapped 
memory, reducing pressure on iommu. We also need to printk a message so that 
a user knows the reason why receive ring was shrunk. Growing it when iommu 
pressure goes down will result in a ping-pong.
2. Force processing of receive and transmit ring. This will ensure that the 
buffers processed by hardware are freed, reducing iommu pressure.

3. If we need to do (1) and (2) a predefined number of times (say 20), stop 
the queue. Stopping the queue in general will cause a ping-pong, so it should 
be avoided as far as possible.

-Amit

On Thursday 07 December 2006 06:28, Stephen Hemminger wrote:
> The more robust way would be to stop the queue (like flow control)
> and return busy. You would need a timer though to handle the case
> where some disk i/o stole all the mappings and then network device flow
> blocked.
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html