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rcu: Move rcu_report_exp_rdp() setting of ->cpu_no_qs.b.exp under lock

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This commit reduces the state space of rcu_report_exp_rdp() by moving
the setting of ->cpu_no_qs.b.exp under the rcu_node structure's ->lock.
The lock isn't really all that important here, given that this per-CPU
field is supposed to be written only by its CPU, but the disabling of
interrupts excludes things like rcu_exp_handler(), which also can write
to this same field.  Avoiding this sort of interleaved access reduces
the state space.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
This commit is contained in:
Paul E. McKenney
2024-10-25 15:56:17 -07:00
committed by Uladzislau Rezki (Sony)
parent d16e32f75f
commit e2bd168295
1 changed files with 1 additions and 1 deletions
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kernel/rcu/tree_exp.h
+1 -1
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@@ -260,8 +260,8 @@ static void rcu_report_exp_rdp(struct rcu_data *rdp)
unsigned long flags;
struct rcu_node *rnp = rdp->mynode;
WRITE_ONCE(rdp->cpu_no_qs.b.exp, false);
raw_spin_lock_irqsave_rcu_node(rnp, flags);
WRITE_ONCE(rdp->cpu_no_qs.b.exp, false);
rcu_report_exp_cpu_mult(rnp, flags, rdp->grpmask, true);
}