Messages in this thread | | | Subject | Re: [Experimental CPU Hotplug PATCH] - Move migrate_all_tasks to CPU_DEAD handling | From | Rusty Russell <> | Date | Thu, 08 Apr 2004 08:55:56 +1000 |
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On Thu, 2004-04-08 at 00:17, Srivatsa Vaddagiri wrote: > On Wed, Apr 07, 2004 at 03:32:12PM +1000, Rusty Russell wrote: > > But other tasks can do a getaffinity() on it and see the wrong affinity. > > Probably not a big issue. > > hmm .. the fact that getaffinity reads the cpus_allowed mask w/o doing > lock_cpu_hotplug makes it already racy wrt setaffinity?
But that's OK: that's a user race. It's like reading a file at the same time as writing it.
> Maybe it needs to take CPU hotplug sem before it reads the mask?
Yes, taking it in both syscalls would work, too.
> I would like to run my stress tests for longer time before I send it > for inclusion (i would be on vacation till next tuesday ..so maybe i will send > in the patch after that!)
Thanks. BTW, can you take a look at the FIXME: in xics.c and change it to be dynamic. Joel is having trouble proving it's a problem, and yet Anton assures me that ioremap is needed, so CPUs not present at boot which are brought in should be failing...
Thanks! Rusty. -- Anyone who quotes me in their signature is an idiot -- Rusty Russell
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