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rcu: Add leaf-node macros 

This commit adds rcu_first_leaf_node() that returns a pointer to
the first leaf rcu_node structure in the specified RCU flavor and an
rcu_is_leaf_node() that returns true iff the specified rcu_node structure
is a leaf.  This commit also uses these macros where appropriate.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Nicholas Piggin <npiggin@gmail.com>
This commit is contained in:
Paul E. McKenney 2018-04-13 17:11:44 -07:00
parent 4317228ad9
commit 5b4c11d54b
3 changed files with 12 additions and 7 deletions
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11
kernel/rcu/rcu.h
View File

@ -270,6 +270,12 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
}
}
/* Returns first leaf rcu_node of the specified RCU flavor. */
#define rcu_first_leaf_node(rsp) ((rsp)->level[rcu_num_lvls - 1])
/* Is this rcu_node a leaf? */
#define rcu_is_leaf_node(rnp) ((rnp)->level == rcu_num_lvls - 1)
/*
* Do a full breadth-first scan of the rcu_node structures for the
* specified rcu_state structure.
@ -284,8 +290,7 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
* rcu_node tree with but one rcu_node structure, this loop is a no-op.
*/
#define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
for ((rnp) = &(rsp)->node[0]; \
(rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++)
for ((rnp) = &(rsp)->node[0]; !rcu_is_leaf_node(rsp, rnp); (rnp)++)
/*
* Scan the leaves of the rcu_node hierarchy for the specified rcu_state
@ -294,7 +299,7 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
* It is still a leaf node, even if it is also the root node.
*/
#define rcu_for_each_leaf_node(rsp, rnp) \
for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
for ((rnp) = rcu_first_leaf_node(rsp); \
(rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
/*

4
kernel/rcu/tree.c
View File

@ -2398,7 +2398,7 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
return;
}
WARN_ON_ONCE(oldmask); /* Any child must be all zeroed! */
WARN_ON_ONCE(rnp->level != rcu_num_lvls - 1 &&
WARN_ON_ONCE(!rcu_is_leaf_node(rnp) &&
rcu_preempt_blocked_readers_cgp(rnp));
rnp->qsmask &= ~mask;
trace_rcu_quiescent_state_report(rsp->name, rnp->gpnum,
@ -4056,7 +4056,7 @@ static void __init rcu_init_one(struct rcu_state *rsp)
init_swait_queue_head(&rsp->gp_wq);
init_swait_queue_head(&rsp->expedited_wq);
rnp = rsp->level[rcu_num_lvls - 1];
rnp = rcu_first_leaf_node(rsp);
for_each_possible_cpu(i) {
while (i > rnp->grphi)
rnp++;

4
kernel/rcu/tree_plugin.h
View File

@ -182,7 +182,7 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp)
raw_lockdep_assert_held_rcu_node(rnp);
WARN_ON_ONCE(rdp->mynode != rnp);
WARN_ON_ONCE(rnp->level != rcu_num_lvls - 1);
WARN_ON_ONCE(!rcu_is_leaf_node(rnp));
/*
* Decide where to queue the newly blocked task. In theory,
@ -533,7 +533,7 @@ void rcu_read_unlock_special(struct task_struct *t)
rnp = t->rcu_blocked_node;
raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
WARN_ON_ONCE(rnp != t->rcu_blocked_node);
WARN_ON_ONCE(rnp->level != rcu_num_lvls - 1);
WARN_ON_ONCE(!rcu_is_leaf_node(rnp));
empty_norm = !rcu_preempt_blocked_readers_cgp(rnp);
empty_exp = sync_rcu_preempt_exp_done(rnp);
smp_mb(); /* ensure expedited fastpath sees end of RCU c-s. */