linux-kernel - [93/98] KVM: fix lock imbalance in kvm_*_irq_source

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Message-Id: <20100126233933.172606623@mini.kroah.org>
Date:	Tue, 26 Jan 2010 15:34:59 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Jiri Slaby <jirislaby@...il.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Avi Kivity <avi@...hat.com>
Subject: [93/98] KVM: fix lock imbalance in kvm_*_irq_source_id()

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Jiri Slaby <jirislaby@...il.com>

commit 0c6ddcebd8303ada6faefa6f72ac18b6230320c4 upstream.

Stanse found 2 lock imbalances in kvm_request_irq_source_id and
kvm_free_irq_source_id. They omit to unlock kvm->irq_lock on fail paths.

Fix that by adding unlock labels at the end of the functions and jump
there from the fail paths.

Signed-off-by: Jiri Slaby <jirislaby@...il.com>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Signed-off-by: Avi Kivity <avi@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 virt/kvm/irq_comm.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -209,11 +209,13 @@ int kvm_request_irq_source_id(struct kvm
 
 	if (irq_source_id >= BITS_PER_LONG) {
 		printk(KERN_WARNING "kvm: exhaust allocatable IRQ sources!\n");
-		return -EFAULT;
+		irq_source_id = -EFAULT;
+		goto unlock;
 	}
 
 	ASSERT(irq_source_id != KVM_USERSPACE_IRQ_SOURCE_ID);
 	set_bit(irq_source_id, bitmap);
+unlock:
 	mutex_unlock(&kvm->irq_lock);
 
 	return irq_source_id;
@@ -229,11 +231,12 @@ void kvm_free_irq_source_id(struct kvm *
 	if (irq_source_id < 0 ||
 	    irq_source_id >= BITS_PER_LONG) {
 		printk(KERN_ERR "kvm: IRQ source ID out of range!\n");
-		return;
+		goto unlock;
 	}
 	for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++)
 		clear_bit(irq_source_id, &kvm->arch.irq_states[i]);
 	clear_bit(irq_source_id, &kvm->arch.irq_sources_bitmap);
+unlock:
 	mutex_unlock(&kvm->irq_lock);
 }
 


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