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Commit a5d6d3a1 authored by Eric Dumazet's avatar Eric Dumazet Committed by Paul E. McKenney
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softirq: A single rcu_bh_qs() call per softirq set is enough 



Calling rcu_bh_qs() after every softirq action is not really needed.
What RCU needs is at least one rcu_bh_qs() per softirq round to note a
quiescent state was passed for rcu_bh.

Note for Paul and myself : this could be inlined as a single instruction
and avoid smp_processor_id()
(sone this_cpu_write(rcu_bh_data.passed_quiesce, 1))

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent fa07a58f

kernel/softirq.c

+1 −3
Original line number Diff line number Diff line
@@ -232,7 +232,6 @@ asmlinkage void __do_softirq(void) 
	bool in_hardirq;

	__u32 pending;

	int softirq_bit;

	int cpu;



	/*

	 * Mask out PF_MEMALLOC s current task context is borrowed for the
@@ -247,7 +246,6 @@ asmlinkage void __do_softirq(void) 
	__local_bh_disable_ip(_RET_IP_, SOFTIRQ_OFFSET);

	in_hardirq = lockdep_softirq_start();



	cpu = smp_processor_id();

restart:

	/* Reset the pending bitmask before enabling irqs */

	set_softirq_pending(0);
@@ -276,11 +274,11 @@ asmlinkage void __do_softirq(void) 
			       prev_count, preempt_count());

			preempt_count_set(prev_count);

		}

		rcu_bh_qs(cpu);

		h++;

		pending >>= softirq_bit;

	}



	rcu_bh_qs(smp_processor_id());

	local_irq_disable();



	pending = local_softirq_pending();