Re: [PATCH RFC tip/core/rcu 28/28] rcu: Fix idle-task checks

From: Josh Triplett
Date: Thu Nov 03 2011 - 00:56:02 EST


On Wed, Nov 02, 2011 at 01:30:49PM -0700, Paul E. McKenney wrote:
> From: Paul E. McKenney <paul.mckenney@xxxxxxxxxx>
>
> RCU has traditionally relied on idle_cpu() to determine whether a given
> CPU is running in the context of an idle task, but recent changes have
> invalidated this approach. This commit therefore switches from idle_cpu
> to "current->pid != 0".

Could you elaborate a bit on "recent changes"? It looks like you mean
commit 908a3283728d92df36e0c7cd63304fd35e93a8a9; if so, could you add
that reference to the commit message?

Also, the hard-coded use of "current->pid != 0" concerns me. Could this
use some existing function? Does idle_task() help? If no appropriate
predicate exists, perhaps it should. is_idle_task(current)?

- Josh Triplett
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