On Tue, Mar 10, 2020 at 03:05:57PM +0000, David Laight wrote:
From: Marco Elver
Sent: 10 March 2020 14:10
...
FWIW, for writes we're already being quite generous, in that plain aligned writes up to word-size are assumed to be "atomic" with the default (conservative) config, i.e. marking such writes is optional. Although, that's a generous assumption that is not always guaranteed to hold (https://lore.kernel.org/lkml/20190821103200.kpufwtviqhpbuv2n@willie-the-truc...).
Remind me to start writing everything in assembler.
Been there, done that. :-/
That and to mark all structure members 'volatile'.
Indeed. READ_ONCE() and WRITE_ONCE() get this same effect, but without pessimizing non-concurrent accesses to those same members. Plus KCSAN knows about READ_ONCE(), WRITE_ONCE(), and also volatile members.
Thanx, Paul