diff options
Diffstat (limited to 'kernel/rcu/rcu.h')
| -rw-r--r-- | kernel/rcu/rcu.h | 43 |
1 files changed, 41 insertions, 2 deletions
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 115616ac3bfa..4a1b9622598b 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -14,6 +14,43 @@ /* * Grace-period counter management. + * + * The two least significant bits contain the control flags. + * The most significant bits contain the grace-period sequence counter. + * + * When both control flags are zero, no grace period is in progress. + * When either bit is non-zero, a grace period has started and is in + * progress. When the grace period completes, the control flags are reset + * to 0 and the grace-period sequence counter is incremented. + * + * However some specific RCU usages make use of custom values. + * + * SRCU special control values: + * + * SRCU_SNP_INIT_SEQ : Invalid/init value set when SRCU node + * is initialized. + * + * SRCU_STATE_IDLE : No SRCU gp is in progress + * + * SRCU_STATE_SCAN1 : State set by rcu_seq_start(). Indicates + * we are scanning the readers on the slot + * defined as inactive (there might well + * be pending readers that will use that + * index, but their number is bounded). + * + * SRCU_STATE_SCAN2 : State set manually via rcu_seq_set_state() + * Indicates we are flipping the readers + * index and then scanning the readers on the + * slot newly designated as inactive (again, + * the number of pending readers that will use + * this inactive index is bounded). + * + * RCU polled GP special control value: + * + * RCU_GET_STATE_COMPLETED : State value indicating an already-completed + * polled GP has completed. This value covers + * both the state and the counter of the + * grace-period sequence number. */ #define RCU_SEQ_CTR_SHIFT 2 @@ -341,11 +378,13 @@ extern void rcu_init_geometry(void); * specified state structure (for SRCU) or the only rcu_state structure * (for RCU). */ -#define srcu_for_each_node_breadth_first(sp, rnp) \ +#define _rcu_for_each_node_breadth_first(sp, rnp) \ for ((rnp) = &(sp)->node[0]; \ (rnp) < &(sp)->node[rcu_num_nodes]; (rnp)++) #define rcu_for_each_node_breadth_first(rnp) \ - srcu_for_each_node_breadth_first(&rcu_state, rnp) + _rcu_for_each_node_breadth_first(&rcu_state, rnp) +#define srcu_for_each_node_breadth_first(ssp, rnp) \ + _rcu_for_each_node_breadth_first(ssp->srcu_sup, rnp) /* * Scan the leaves of the rcu_node hierarchy for the rcu_state structure. |