Otavio Salvador <ota...@ossystems.com.br> writes: > On Mon, Aug 4, 2014 at 6:18 PM, Richard Tollerton <rich.toller...@ni.com> > wrote: >> Otavio Salvador <ota...@ossystems.com.br> writes: >> >>> I am not sure about this one. I see the value you are adding here but >>> I worry how often something can be connected during this process and >>> change the contents along the way. Did you see something as that >>> during your tests? >> >> No, but point taken. I didn't really test "physical" hotplug during >> bootup -- and in particular, for this to be a persisting issue, the >> added/removed device must be removed/added during this boot -- but I >> suppose that is totally possible. >> >> This reflects an underlying race condition, starting at the computation >> of NEWDATA/OLDDATA in the udev initscript, and ending in the tarball >> creation in udev-cache. I suppose that we can mitigate this by spinning >> in udev-cache until the devcache stops changing...? Cheesy, untested, >> dirty RFC follows: > > You need to check the list of files taken by 'tar' and compare. This > mitigates it but does not really solves the issue.
Hmm, I'm confused. If we relied entirely on /dev contents, how would we detect (and correct for) if a device was removed between the execution of udev and of udev-cache? > Maybe we could "copy" the nodes to a tmp area and use this as a > snapshot? The copy should be fast and makes it mostly "atomic". I agree that the copy of the contents of /dev needs to be as fast as possible -- your about using tmpfs as a staging area is well taken. But beyond that, it seems to me that the root issue you articulated is about ensuring adequate synchronization of udev.cache and the tarball; rereading CMP_FILE_LIST in udev-cache thus seems unavoidable. > -- > Otavio Salvador O.S. Systems > http://www.ossystems.com.br http://code.ossystems.com.br > Mobile: +55 (53) 9981-7854 Mobile: +1 (347) 903-9750 -- Richard Tollerton <rich.toller...@ni.com> -- _______________________________________________ Openembedded-core mailing list Openembedded-core@lists.openembedded.org http://lists.openembedded.org/mailman/listinfo/openembedded-core
