The rcu_assign_pointer() macro has changed over time, and the version in Documentation/RCU/whatisRCU.txt has not kept up. This commit brings it into 2017, albeit in a simplified fashion.
Reported-by: Andrea Parri <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]> --- Documentation/RCU/whatisRCU.txt | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-) diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index 5cbd8b2395b8..6b0337008f9c 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -587,20 +587,21 @@ It is extremely simple: write_unlock(&rcu_gp_mutex); } -[You can ignore rcu_assign_pointer() and rcu_dereference() without -missing much. But here they are anyway. And whatever you do, don't -forget about them when submitting patches making use of RCU!] - - #define rcu_assign_pointer(p, v) ({ \ - smp_wmb(); \ - (p) = (v); \ - }) - - #define rcu_dereference(p) ({ \ - typeof(p) _________p1 = p; \ - smp_read_barrier_depends(); \ - (_________p1); \ - }) +[You can ignore rcu_assign_pointer() and rcu_dereference() without missing +much. But here are simplified versions anyway. And whatever you do, +don't forget about them when submitting patches making use of RCU!] + + #define rcu_assign_pointer(p, v) \ + ({ \ + smp_store_release(&(p), (v)); \ + }) + + #define rcu_dereference(p) \ + ({ \ + typeof(p) _________p1 = p; \ + smp_read_barrier_depends(); \ + (_________p1); \ + }) The rcu_read_lock() and rcu_read_unlock() primitive read-acquire -- 2.5.2
