On Mon, May 27, 2019 at 10:57:52AM -0700, Joe Perches wrote: > On Mon, 2019-05-27 at 10:49 -0700, Paul E. McKenney wrote: > > On Mon, May 27, 2019 at 10:21:22AM -0700, Joe Perches wrote: > > > On Mon, 2019-05-27 at 09:10 -0700, Paul E. McKenney wrote: > > > > On Mon, May 27, 2019 at 10:49:57AM +0200, Andrea Parri wrote: > > > > > Quoting Paul [1]: > > > > > > > > > > "Given that a quick (and perhaps error-prone) search of the uses > > > > > of rcu_assign_pointer() in v5.1 didn't find a single use of the > > > > > return value, let's please instead change the documentation and > > > > > implementation to eliminate the return value." > > > > > > > > > > [1] https://lkml.kernel.org/r/20190523135013.GL28207@xxxxxxxxxxxxx > > > > > > > > Queued, thank you! > > > > > > > > Adding the checkpatch maintainers on CC as well. The "do { } while > > > > (0)" prevents the return value from being used, by design. Given the > > > > checkpatch complaint, is there some better way to achieve this? > > > > > > Not sure what the checkpatch complaint is here. > > > > Checkpatch seems to want at least two statements in each > > "do { } while (0)" macro definition: > > > > WARNING: Single statement macros should not use a do {} while (0) loop > > > > > Reading the link above, there seems to be a compiler warning. > > > > The compiler warning is a theoretical issue that is being fixed by this > > patch, and the patch is giving the checkpatch warning. > > > > > Perhaps a statement expression macro with no return value? > > > > > > #define rcu_assign_pointer(p, v) ({ (p) = (v); ; }) > > > > This is at best an acquired taste for me... > > Another ugly possibility could be: > > #define rcu_assign_pointer(p, v) do {if (1) (p) = (v); } while (0) And, not to be left out, another ugly possibility might be: #define rcu_assign_pointer(p, v) ((void)((p) = (v))) > Possibly the best option would be to ignore checkpatch here > and just add a comment above the use. Works for me! Thanx, Paul
