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rcu: Produce last "CleanupMore" trace only if late-breaking request 

Currently Tree RCU's clean-up code emits a "CleanupMore" trace event in
response to late-arriving grace-period requests even if the grace period
was already requested. This makes "CleanupMore" show up an extra time (in
addition to once for each rcu_node structure that was previously marked
with the request), and for no good reason.  This commit therefore avoids
emitting this trace message unless the the only request for this next
grace period arrived during or after the cleanup scan of the rcu_node
structures.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Joel Fernandes (Google) 2018-05-13 20:15:40 -07:00 committed by Paul E. McKenney
parent a2165e4168
commit 5b55072f22
1 changed files with 1 additions and 1 deletions
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2
kernel/rcu/tree.c
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@ -2069,7 +2069,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
rsp->gp_state = RCU_GP_IDLE;
/* Check for GP requests since above loop. */
rdp = this_cpu_ptr(rsp->rda);
if (ULONG_CMP_LT(rnp->gp_seq, rnp->gp_seq_needed)) {
if (!needgp && ULONG_CMP_LT(rnp->gp_seq, rnp->gp_seq_needed)) {
trace_rcu_this_gp(rnp, rdp, rnp->gp_seq_needed,
TPS("CleanupMore"));
needgp = true;