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rcu: Make rcu_gp_cleanup() write only once to ->gp_flags

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At the end of rcu_gp_cleanup(), if another grace period is needed, but
not via rcu_accelerate_cbs(), the ->gp_flags field is written twice,
once when making the new grace-period request, and once when clearing
all other types of requests.  This commit therefore adds an else-clause
to avoid this double write.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2018-04-22 15:06:05 -07:00
parent 26d950a945
commit 18390aeae7
1 changed files with 2 additions and 1 deletions
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3
kernel/rcu/tree.c
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@ -2117,8 +2117,9 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
rsp->gp_req_activity = jiffies;
trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gpnum),
TPS("newreq"));
} else {
WRITE_ONCE(rsp->gp_flags, rsp->gp_flags & RCU_GP_FLAG_INIT);
}
WRITE_ONCE(rsp->gp_flags, rsp->gp_flags & RCU_GP_FLAG_INIT);
raw_spin_unlock_irq_rcu_node(rnp);
}