diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2016-11-28 12:08:49 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-01-25 12:54:22 -0800 |
| commit | d85b62f18d543c663cbdd6061054efeb9e66cee7 (patch) | |
| tree | f057b276302012d5f62a6c0a2727e0b334e26866 /kernel/rcu/tree.h | |
| parent | f2c4689640e9a34bc45c013032185ed4ce47e7ff (diff) | |
srcu: Force full grace-period ordering
If a process invokes synchronize_srcu(), is delayed just the right amount
of time, and thus does not sleep when waiting for the grace period to
complete, there is no ordering between the end of the grace period and
the code following the synchronize_srcu(). Similarly, there can be a
lack of ordering between the end of the SRCU grace period and callback
invocation.
This commit adds the necessary ordering.
Reported-by: Lance Roy <ldr709@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Further smp_mb() adjustment per email with Lance Roy. ]
Diffstat (limited to 'kernel/rcu/tree.h')
| -rw-r--r-- | kernel/rcu/tree.h | 12 |
1 files changed, 0 insertions, 12 deletions
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index fe98dd24adf8..abcc25bdcb29 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -688,18 +688,6 @@ static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll) #endif /* #ifdef CONFIG_RCU_TRACE */ /* - * Place this after a lock-acquisition primitive to guarantee that - * an UNLOCK+LOCK pair act as a full barrier. This guarantee applies - * if the UNLOCK and LOCK are executed by the same CPU or if the - * UNLOCK and LOCK operate on the same lock variable. - */ -#ifdef CONFIG_PPC -#define smp_mb__after_unlock_lock() smp_mb() /* Full ordering for lock. */ -#else /* #ifdef CONFIG_PPC */ -#define smp_mb__after_unlock_lock() do { } while (0) -#endif /* #else #ifdef CONFIG_PPC */ - -/* * Wrappers for the rcu_node::lock acquire and release. * * Because the rcu_nodes form a tree, the tree traversal locking will observe |