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Date: Wed, 6 Jun 2012 17:27:04 +0100 From: Matthew Garrett <mjg59@...f.ucam.org> To: Khalid Aziz <khalid.aziz@...com> Cc: linux-kernel@...r.kernel.org, bhelgaas@...gle.com, linux-pci@...r.kernel.org Subject: Re: [PATCH] Disable Bus Master on PCI device shutdown On Wed, Jun 06, 2012 at 10:17:43AM -0600, Khalid Aziz wrote: > That is a good piece of information. I see your concern and agree with > it. My take is shutdown method for the drivers will end all active I/O > and clear the I/O queue. This should take care of any DMA caused by an > I/O request originating in the kernel. For devices like NIC, a DMA can > be triggered by an incoming packet and I am trying to stop that by > disabling Bus Master bit. This is the issue that was reported on kexec > mailing list in July of last year and it involved qla driver. I observed > similar problem with kexec on ia64 many years ago and had written a > patch to disable Bus Master bit on kexec. This patch was in ia64 tree > for some time before it was removed. HP shipped kernels with this patch > for many years and those kernels have been in deployment in field for > some 7+ years with no problems. If the qla driver knows that this is safe, then can't this just be done in the qla driver? -- Matthew Garrett | mjg59@...f.ucam.org -- 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/
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