linux-kernel - [GIT PULL] x86/irq change for v4.12

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Message-ID: <20170501114000.4ognhldpkye25s4l@gmail.com>
Date:   Mon, 1 May 2017 13:40:01 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] x86/irq change for v4.12

Linus,

Please pull the latest x86-irq-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-irq-for-linus

   # HEAD: c0edbd4a1693600d6eb9e2faad452638c35391f7 x86/irq: Optimize free vector check in the CPU offline path

A single commit that micro-optimizes an IRQ vectors code path in the CPU offlining 
code.

 Thanks,

	Ingo

------------------>
Chen Yu (1):
      x86/irq: Optimize free vector check in the CPU offline path


 arch/x86/kernel/irq.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 4d8183b5f113..f34fe7444836 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -394,6 +394,9 @@ int check_irq_vectors_for_cpu_disable(void)
 		    !cpumask_subset(&affinity_new, &online_new))
 			this_count++;
 	}
+	/* No need to check any further. */
+	if (!this_count)
+		return 0;
 
 	count = 0;
 	for_each_online_cpu(cpu) {
@@ -411,8 +414,10 @@ int check_irq_vectors_for_cpu_disable(void)
 		for (vector = FIRST_EXTERNAL_VECTOR;
 		     vector < first_system_vector; vector++) {
 			if (!test_bit(vector, used_vectors) &&
-			    IS_ERR_OR_NULL(per_cpu(vector_irq, cpu)[vector]))
-			    count++;
+			    IS_ERR_OR_NULL(per_cpu(vector_irq, cpu)[vector])) {
+				if (++count == this_count)
+					return 0;
+			}
 		}
 	}