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From:   Frederic Weisbecker <frederic@kernel.org>
To:     LKML <linux-kernel@vger.kernel.org>
Cc:     Frederic Weisbecker <frederic@kernel.org>,
        Levin Alexander <alexander.levin@verizon.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Mauro Carvalho Chehab <mchehab@s-opensource.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Hannes Frederic Sowa <hannes@stressinduktion.org>,
        "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
        Wanpeng Li <wanpeng.li@hotmail.com>,
        Dmitry Safonov <dima@arista.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Radu Rendec <rrendec@arista.com>,
        Ingo Molnar <mingo@kernel.org>,
        Stanislaw Gruszka <sgruszka@redhat.com>,
        Rik van Riel <riel@redhat.com>,
        Eric Dumazet <edumazet@google.com>,
        David Miller <davem@davemloft.net>
Subject: [RFC PATCH 3/4] softirq: Defer to workqueue when rescheduling is needed
Date:   Fri, 19 Jan 2018 16:46:13 +0100
Message-Id: <1516376774-24076-4-git-send-email-frederic@kernel.org>
In-Reply-To: <1516376774-24076-1-git-send-email-frederic@kernel.org>
References: <1516376774-24076-1-git-send-email-frederic@kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
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One more step toward converting ksoftirqd to per vector workqueues.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Dmitry Safonov <dima@arista.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Levin Alexander <alexander.levin@verizon.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Radu Rendec <rrendec@arista.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com>
---
 kernel/softirq.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/kernel/softirq.c b/kernel/softirq.c
index becb1d9..bb0cffa 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -369,16 +369,14 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
 
 	pending = local_softirq_pending() & ~softirq->pending_work_mask;
 	if (pending) {
-		if (need_resched()) {
-			wakeup_softirqd();
-		} else {
-			/* Vectors that got re-enqueued are threaded */
-			if (executed & pending)
-				do_softirq_workqueue(executed & pending);
-			pending &= ~executed;
-			if (pending)
-				goto restart;
-		}
+		if (need_resched())
+			executed = pending;
+		/* Vectors that got re-enqueued are threaded */
+		if (executed & pending)
+			do_softirq_workqueue(executed & pending);
+		pending &= ~executed;
+		if (pending)
+			goto restart;
 	}
 
 	lockdep_softirq_end(in_hardirq);
-- 
2.7.4