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rcu: Add comment headers to expedited-grace-period counter functions

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These functions (rcu_exp_gp_seq_start(), rcu_exp_gp_seq_end(),
rcu_exp_gp_seq_snap(), and rcu_exp_gp_seq_done() seemed too obvious
to comment when written, but not so much when being documented.
This commit therefore adds header comments to each of them.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Paul E. McKenney 2016-12-18 13:31:02 -08:00
parent 630c7ed9ca
commit 09e2db37ec
1 changed files with 17 additions and 1 deletions
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18
kernel/rcu/tree_exp.h
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@ -20,16 +20,26 @@
* Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com> * Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
*/ */
/* Wrapper functions for expedited grace periods. */ /*
* Record the start of an expedited grace period.
*/
static void rcu_exp_gp_seq_start(struct rcu_state *rsp) static void rcu_exp_gp_seq_start(struct rcu_state *rsp)
{ {
rcu_seq_start(&rsp->expedited_sequence); rcu_seq_start(&rsp->expedited_sequence);
} }
/*
* Record the end of an expedited grace period.
*/
static void rcu_exp_gp_seq_end(struct rcu_state *rsp) static void rcu_exp_gp_seq_end(struct rcu_state *rsp)
{ {
rcu_seq_end(&rsp->expedited_sequence); rcu_seq_end(&rsp->expedited_sequence);
smp_mb(); /* Ensure that consecutive grace periods serialize. */ smp_mb(); /* Ensure that consecutive grace periods serialize. */
} }
/*
* Take a snapshot of the expedited-grace-period counter.
*/
static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp) static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp)
{ {
unsigned long s; unsigned long s;
@ -39,6 +49,12 @@ static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp)
trace_rcu_exp_grace_period(rsp->name, s, TPS("snap")); trace_rcu_exp_grace_period(rsp->name, s, TPS("snap"));
return s; return s;
} }
/*
* Given a counter snapshot from rcu_exp_gp_seq_snap(), return true
* if a full expedited grace period has elapsed since that snapshot
* was taken.
*/
static bool rcu_exp_gp_seq_done(struct rcu_state *rsp, unsigned long s) static bool rcu_exp_gp_seq_done(struct rcu_state *rsp, unsigned long s)
{ {
return rcu_seq_done(&rsp->expedited_sequence, s); return rcu_seq_done(&rsp->expedited_sequence, s);