From: Rusty Russell <[email protected]> Date: Tue, 28 Apr 2015 15:29:45 +0930
> da91309e0a7e (cpumask: Utility function to set n'th cpu...) created a > genuinely weird function. I never saw it before, it went through DaveM. > (He only does this to make us other maintainers feel better about our own > mistakes.) > > cpumask_set_cpu_local_first's purpose is say "I need to spread things > across N online cpus, choose the ones on this numa node first"; you call > it in a loop. > > It can fail. One of the two callers ignores this, the other aborts and > fails the device open. > > It can fail in two ways: allocating the off-stack cpumask, or through a > convoluted codepath which AFAICT can only occur if cpu_online_mask > changes. Which shouldn't happen, because if cpu_online_mask can change > while you call this, it could return a now-offline cpu anyway. > > It contains a nonsensical test "!cpumask_of_node(numa_node)". This was > drawn to my attention by Geert, who said this causes a warning on Sparc. > It sets a single bit in a cpumask instead of returning a cpu number, > because that's what the callers want. > > It could be made more efficient by passing the previous cpu rather than > an index, but that would be more invasive to the callers. > > Fixes: da91309e0a7e8966d916a74cce42ed170fde06bf > Signed-off-by: Rusty Russell <[email protected]> Acked-by: David S. Miller <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
