2011-02-07 11:01:13

by Jan Beulich

Subject: x86: mis-named percpu_xchg_op() after switch to cmpxchg?

Other than its name implies, with the switch to use cmpxchg instead of
xchg (commit 8270137a0d50507a5b40f880db636527045b8466) this
macro is no longer suitable for accessing anything that may be written
by other than the local CPU (i.e. anything but the various this_cpu
accessors). Shouldn't it therefore get renamed to eg this_cpu_xchg_op()?

Jan

2011-02-07 17:17:29

by Christoph Lameter (Ampere)

Subject: Re: x86: mis-named percpu_xchg_op() after switch to cmpxchg?

On Mon, 7 Feb 2011, Jan Beulich wrote:

> Other than its name implies, with the switch to use cmpxchg instead of
> xchg (commit 8270137a0d50507a5b40f880db636527045b8466) this
> macro is no longer suitable for accessing anything that may be written
> by other than the local CPU (i.e. anything but the various this_cpu
> accessors). Shouldn't it therefore get renamed to eg this_cpu_xchg_op()?

No. The intend of the percpu_xchg_op was also to provide local cpu only
semantics. percpu_xx operations in general have the same semantics as
this_cpu operations.