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authorStefan Richter <stefanr@s5r6.in-berlin.de>2008-08-19 21:30:17 +0200
committerStefan Richter <stefanr@s5r6.in-berlin.de>2008-10-15 22:21:09 +0200
commitfc392fe83176cefbab99f9d12e6e27395aa2b5d0 (patch)
tree070fe832dff6cea485333b2572efb4c8b716a410 /drivers/firewire
parent11305c3eda233d3aff52d755a2d6c1706c509962 (diff)
ieee1394: survive a few seconds connection loss
There are situations when nodes vanish from the bus and come back in quickly thereafter: - When certain bus-powered hubs are plugged in, - when certain disk enclosures are switched from self-power to bus power or vice versa and break the daisy chain during the transition, - when the user plugs a cable out and quickly plugs it back in, e.g. to reorder a daisy chain (works on Mac OS X if done quickly enough), - when certain hubs temporarily malfunction during high bus traffic. The ieee1394 driver's nodemgr already contained a function to set vanished nodes aside into "limbo"; i.e. they wouldn't actually be deleted right away. (In fact, only unloading the driver or writing into an obscure sysfs attribute would delete them eventually.) If nodes reappeared later, they would be resurrected out of limbo. Moving nodes into and out of limbo was accompanied with calling the .suspend() and .resume() driver methods of the drivers which were bound to a respective node's unit directories. Not only is this somewhat strange due to the intended use of these driver methods for power management, also the sbp2 driver in particular does not implement .suspend() and .resume(). Hence sbp2 would be disconnected from devices in situations as listed above. We now: - leave drivers bound when nodes go into limbo, - call the drivers' .update() when nodes come out of limbo, - automatically delete in-limbo nodes 3 seconds after the last bus reset and bus rescan. - Because of the automatic removal, the now obsolete bus attribute /sys/bus/ieee1394/destroy_node is removed. This especially lets sbp2 survive brief disconnections. You can for example yank a disk's cable and plug it back in while reading the respective disk with dd, but dd will happily continue as if nothing happened. Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Diffstat (limited to 'drivers/firewire')
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