Re: [PATCH] NFS: Fix RCU warnings in nfs_inode_return_delegation_noreclaim() [ver #2]

David Howells
2010-03-29T22:59:19Z

Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:

> Only on Alpha. Otherwise only a volatile access.

Whilst that is true, it's the principle of the thing. The extra barrier
shouldn't be emitted on Alpha. If Alpha's no longer important, then can we
scrap smp_read_barrier_depends()?

My point is that some of these rcu_dereference*()'s are unnecessary. If
there're required for correctness tracking purposes, fine; but can we have a
macro that is just a dummy for the purpose of stripping the pointer Sparse
annotation? One that doesn't invoke rcu_dereference_raw() and interpolate a
barrier, pretend or otherwise, when there's no second reference to order
against.

David