diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-03-22 15:26:18 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-04-18 11:38:22 -0700 |
| commit | 80a7956fe36c2ee40c6ff12c77926d267802b7c8 (patch) | |
| tree | e8140078439a4e0fda35fa54d000212be1f6f00e /kernel/rcu/rcu.h | |
| parent | f1ec57a462314f3d1cd0c9c8a04979228aa9d38c (diff) | |
| download | linux-80a7956fe36c2ee40c6ff12c77926d267802b7c8.tar.bz2 | |
srcu: Merge ->srcu_state into ->srcu_gp_seq
Updating ->srcu_state and ->srcu_gp_seq will lead to extremely complex
race conditions given multiple callback queues, so this commit takes
advantage of the two-bit state now available in rcu_seq counters to
store the state in the bottom two bits of ->srcu_gp_seq.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/rcu.h')
| -rw-r--r-- | kernel/rcu/rcu.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 87a0ac95b551..73e16ec4054b 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -82,6 +82,16 @@ static inline int rcu_seq_state(unsigned long s) return s & RCU_SEQ_STATE_MASK; } +/* + * Set the state portion of the pointed-to sequence number. + * The caller is responsible for preventing conflicting updates. + */ +static inline void rcu_seq_set_state(unsigned long *sp, int newstate) +{ + WARN_ON_ONCE(newstate & ~RCU_SEQ_STATE_MASK); + WRITE_ONCE(*sp, (*sp & ~RCU_SEQ_STATE_MASK) + newstate); +} + /* Adjust sequence number for start of update-side operation. */ static inline void rcu_seq_start(unsigned long *sp) { |