linux-kernel - [PATCH] x86_64 irq: Use irq_domain in ioapic_retrigger

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Date:	Tue, 17 Oct 2006 12:02:38 -0600
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Linus Torvalds <torvalds@...l.org>
Cc:	Andrew Morton <akpm@...l.org>, Andi Kleen <ak@...e.de>,
	<linux-kernel@...r.kernel.org>,
	Natalie Protasevich <Natalie.Protasevich@...SYS.com>,
	Yinghai Lu <yinghai.lu@....com>
Subject: [PATCH] x86_64 irq: Use irq_domain in ioapic_retrigger_irq


Thanks to YH Lu for spotting this.  It appears I missed
this function when I refactored allocate_irq_vector and
introduced irq_domain, with the result that all retriggered
irqs would go to cpu 0 even if we were not prepared to
receive them there.

While reviewing YH's patch I also noticed that this function was
missing locking, and since I am now reading two values from
two diffrent arrays that looks like a race we might be able
to hit in the real world.

Cc: Yinghai Lu <yinghai.lu@....com>
Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---
 arch/x86_64/kernel/io_apic.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86_64/kernel/io_apic.c b/arch/x86_64/kernel/io_apic.c
index 49e94f7..2207d4a 100644
--- a/arch/x86_64/kernel/io_apic.c
+++ b/arch/x86_64/kernel/io_apic.c
@@ -1255,12 +1255,15 @@ static int ioapic_retrigger_irq(unsigned
 {
 	cpumask_t mask;
 	unsigned vector;
+	unsigned long flags;
 
+	spin_lock_irqsave(&vector_lock, flags);
 	vector = irq_vector[irq];
 	cpus_clear(mask);
-	cpu_set(vector >> 8, mask);
+	cpu_set(first_cpu(irq_domain[irq]), mask);
 
-	send_IPI_mask(mask, vector & 0xff);
+	send_IPI_mask(mask, vector);
+	spin_unlock_irqrestore(&vector_lock, flags);
 
 	return 1;
 }
-- 
1.4.2.rc3.g7e18e-dirty

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