Patch "x86/apic: Handle zero vector gracefully in clear_vector_irq()" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    x86/apic: Handle zero vector gracefully in clear_vector_irq()

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-apic-handle-zero-vector-gracefully-in-clear_vector_irq.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 1bdb8970392a68489b469c3a330a1adb5ef61beb Mon Sep 17 00:00:00 2001
From: Keith Busch <keith.busch@intel.com>
Date: Wed, 27 Apr 2016 14:22:32 -0600
Subject: x86/apic: Handle zero vector gracefully in clear_vector_irq()

From: Keith Busch <keith.busch@intel.com>

commit 1bdb8970392a68489b469c3a330a1adb5ef61beb upstream.

If x86_vector_alloc_irq() fails x86_vector_free_irqs() is invoked to cleanup
the already allocated vectors. This subsequently calls clear_vector_irq().

The failed irq has no vector assigned, which triggers the BUG_ON(!vector) in
clear_vector_irq().

We cannot suppress the call to x86_vector_free_irqs() for the failed
interrupt, because the other data related to this irq must be cleaned up as
well. So calling clear_vector_irq() with vector == 0 is legitimate.

Remove the BUG_ON and return if vector is zero,

[ tglx: Massaged changelog ]

Fixes: b5dc8e6c21e7 "x86/irq: Use hierarchical irqdomain to manage CPU interrupt vectors"
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kernel/apic/vector.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -254,7 +254,8 @@ static void clear_irq_vector(int irq, st
 	struct irq_desc *desc;
 	int cpu, vector;
 
-	BUG_ON(!data->cfg.vector);
+	if (!data->cfg.vector)
+		return;
 
 	vector = data->cfg.vector;
 	for_each_cpu_and(cpu, data->domain, cpu_online_mask)


Patches currently in stable-queue which might be from keith.busch@intel.com are

queue-4.4/block-loop-fix-filesystem-corruption-in-case-of-aio-dio.patch
queue-4.4/x86-apic-handle-zero-vector-gracefully-in-clear_vector_irq.patch