On Tue, Oct 24, 2017 at 11:31:04AM +0200, Ingo Molnar wrote:

* Paul E. McKenney [off-list ref] wrote:

quoted

From: Will Deacon <redacted>

lockless_dereference is a nice idea, but its gained little traction in
kernel code since it's introduction three years ago. This is partly

s/its/it
s/it's/its

Crikey, no idea what happened there!

quoted

because it's a pain to type, but also because using READ_ONCE instead
will work correctly on all architectures apart from Alpha, which is a
fully supported but somewhat niche architecture these days.

This patch moves smp_read_barrier_depends() (a NOP on all architectures
other than Alpha) from lockless_dereference into READ_ONCE, converts
the few actual users over to READ_ONCE and then finally removes
lockless_dereference altogether.

Nit: if we refer to smp_read_barrier_depends() with parentheses (which is the nice 
thing to do for function-alike symbols), then we should do the same with 
READ_ONCE() and lockless_dereference() as well.

Also, could we please split this into three patches:

 #1: Add smp_read_barrier_depends() to READ_ONCE()
 #2: Convert all lockless_dereference() users to READ_ONCE()
 #3: Remove the now unused lockless_dereference() API

to make it easier to analyze if bisected to, should any problems arise?

Sure, I'll do that now.

Will