Re: [PATCH] xchg/alpha: Add unconditional memory barrier to cmpxchg

2018-02-21 Thread Andrea Parri
On Wed, Feb 21, 2018 at 11:21:38AM +, Will Deacon wrote: > Hi Andrea, > > On Tue, Feb 20, 2018 at 07:45:56PM +0100, Andrea Parri wrote: > > Continuing along with the fight against smp_read_barrier_depends() [1] > > (or rather, against its improper use), add an unconditional barrier to > > cmpx

Re: [PATCH] xchg/alpha: Add unconditional memory barrier to cmpxchg

2018-02-21 Thread Will Deacon
Hi Andrea, On Tue, Feb 20, 2018 at 07:45:56PM +0100, Andrea Parri wrote: > Continuing along with the fight against smp_read_barrier_depends() [1] > (or rather, against its improper use), add an unconditional barrier to > cmpxchg. This guarantees that dependency ordering is preserved when a > depe

Re: [PATCH] xchg/alpha: Add unconditional memory barrier to cmpxchg

2018-02-20 Thread Paul E. McKenney
On Tue, Feb 20, 2018 at 07:45:56PM +0100, Andrea Parri wrote: > Continuing along with the fight against smp_read_barrier_depends() [1] > (or rather, against its improper use), add an unconditional barrier to > cmpxchg. This guarantees that dependency ordering is preserved when a > dependency is he

[PATCH] xchg/alpha: Add unconditional memory barrier to cmpxchg

2018-02-20 Thread Andrea Parri
Continuing along with the fight against smp_read_barrier_depends() [1] (or rather, against its improper use), add an unconditional barrier to cmpxchg. This guarantees that dependency ordering is preserved when a dependency is headed by an unsuccessful cmpxchg. As it turns out, the change could en