Messages in this thread | | | Date | Wed, 18 Oct 2006 08:57:22 -0600 | From | Matthew Wilcox <> | Subject | Re: [PATCH] Block on access to temporarily unavailable pci device |
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On Wed, Oct 18, 2006 at 08:51:04AM -0600, Matthew Wilcox wrote: > This reimplementation uses a global wait queue and a bit per device. > I've open-coded prepare_to_wait() / finish_wait() as I could optimise > it significantly by knowing that the pci_lock protected us at all points.
I forgot to report how I've tested it. Using the 'test' patch from yesterday, I have two processes running lspci in an infinite loop. When I write a 1 to /sys/bus/pci/devices/0000\:00\:01.0/block, they both halt. When I write a 0, they both resume.
Then I tried doing echo 0 >/sys/bus/pci/devices/0000\:00\:01.0/block a second time, and I got the WARNing I expected.
animal:~# echo 1 >/sys/bus/pci/devices/0000\:00\:01.0/block animal:~# echo 1 >/sys/bus/pci/devices/0000\:00\:01.0/block animal:~# echo 0 >/sys/bus/pci/devices/0000\:00\:01.0/block
They both resumed (as expected; we don't support nesting).
animal:~# echo 1 >/sys/bus/pci/devices/0000\:00\:01.0/block animal:~# echo 1 >/sys/bus/pci/devices/0000\:00\:01.1/block animal:~# echo 0 >/sys/bus/pci/devices/0000\:00\:01.0/block animal:~# echo 0 >/sys/bus/pci/devices/0000\:00\:01.1/block
Both resumed only after the second echo 0 (as lspci reads all devices before printing anything).
It's not exactly rigorous testing, but I couldn't think of any other cases to try. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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