Messages in this thread | | | From | Milton Miller <> | Subject | Re: calling smp_call_function_many() with non-stable CPU mask | Date | Tue, 01 Feb 2011 02:45:15 -0600 |
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> There are a couple of examples of smp_call_function_many() getting > called with mm_cpumask() as the first argument. Since that mask > generally can change while smp_call_function_many() is executing, > it seems there might be a problem with the case where that mask > becomes empty after the initial checks, but before the mask is made > permanent (by copying into data->cpumask). > > Shouldn't there be a check of data->refs being zero right after > setting it (to avoid having csd_lock_wait() wait for a remote CPU > to clear the lock flag, and to avoid adding the entry to > call_function.queue)? > > If that isn't considered necessary, is it then incorrect to pass > in-flight CPU masks to smp_call_function_many() (and should > this requirement then be documented somewhere, and the > existing calls all be inspected for correctness)? >
Mike Galbraith just brought this up, and I supplied a patch, and even a rediff on top of other changes:
http://lkml.indiana.edu/hypermail/linux/kernel/1101.3/02813.html http://lkml.indiana.edu/hypermail/linux/kernel/1101.3/03172.html
http://lkml.indiana.edu/hypermail/linux/kernel/1102.0/00017.html
This doesn't address https://bugzilla.kernel.org/show_bug.cgi?id=23042 which is x86 not expecting the mask to be cleared while its thinking about the mask.
milton
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