linux-kernel - Re: [PATCH v5 1/4] kvm: Extend irqfd to support level interrupts

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Message-ID: <20120717212612.GA2018@redhat.com>
Date:	Wed, 18 Jul 2012 00:26:12 +0300
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Alex Williamson <alex.williamson@...hat.com>
Cc:	avi@...hat.com, gleb@...hat.com, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, jan.kiszka@...mens.com
Subject: Re: [PATCH v5 1/4] kvm: Extend irqfd to support level interrupts

On Mon, Jul 16, 2012 at 02:33:47PM -0600, Alex Williamson wrote:
> @@ -96,6 +183,9 @@ irqfd_shutdown(struct work_struct *work)
>  	 * It is now safe to release the object's resources
>  	 */
>  	eventfd_ctx_put(irqfd->eventfd);
> +
> +	_irq_source_put(irqfd->source);
> +
>  	kfree(irqfd);
>  }
>  

Hang on, this is a bug I think. This is done asynchronously.  So this
means that I can assign MAX number of irqfds, then close one, and now
assign will fail because deassign did not get freed.

Maybe we can solve this by flushing wq before assign?
Looks a bit fragile but may be enough - need to document well.

-- 
MST
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