On 01/09/2016 16:40, Pranith Kumar wrote: >> > >> > bh is shared since it is equal to ctx->first_bh or >> > ctx->first_bh->...->next. While the compiler will always order the load >> > of bh->next after the load of ctx->first_bh and any previous load of >> > bh->next, this may not be the case for the processor. Only the DEC >> > Alpha has this behavior, but it _can_ happen. > In that case there are a bunch of places in the same file where we > need to insert this barrier. I also guarantee that there are many more > files which would need this barrier if we examine closely.
If it's protected by a lock, it's not necessary. If you don't like smp_read_barrier_depends, you can introduce a synonym for atomic_rcu_read with another name. But the functionality is required. Paolo
