On Mon, 2017-10-23 at 21:07 +0000, Paul E. McKenney wrote: > From: Mark Rutland <mark.rutland@xxxxxxx> > > For several reasons, it is desirable to use {READ,WRITE}_ONCE() in > preference to ACCESS_ONCE(), and new code is expected to use one of the > former. So far, there's been no reason to change most existing uses of > ACCESS_ONCE(), as these aren't currently harmful. > > However, for some features it is necessary to instrument reads and > writes separately, which is not possible with ACCESS_ONCE(). This > distinction is critical to correct operation. > > It's possible to transform the bulk of kernel code using the Coccinelle > script below. However, this doesn't pick up some uses, including those > in <linux/average.h>. As a preparatory step, this patch converts the > file to use {READ,WRITE}_ONCE() consistently. > > At the same time, this patch addds missing includes necessary for > {READ,WRITE}_ONCE(), *BUG_ON*(), and ilog2(). > > ---- > virtual patch > > @ depends on patch @ > expression E1, E2; > @@ > > - ACCESS_ONCE(E1) = E2 > + WRITE_ONCE(E1, E2) > > @ depends on patch @ > expression E; > @@ > > - ACCESS_ONCE(E) > + READ_ONCE(E) > ---- > > Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> > Cc: Johannes Berg <johannes.berg@xxxxxxxxx> Reviewed-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx> Let me know if you want me to apply this, since I seem to be the average.h maintainer :-) johannes