linux-kernel - Re: [PATCH] drivers/xen/evtchn.c: Check failure for evtchn_make

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Date:	Thu, 28 Aug 2014 16:49:57 +0100
From:	David Vrabel <david.vrabel@...rix.com>
To:	Chen Gang <gang.chen.5i5j@...il.com>, <konrad.wilk@...cle.com>,
	<boris.ostrovsky@...cle.com>
CC:	<xen-devel@...ts.xenproject.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drivers/xen/evtchn.c: Check failure for evtchn_make_refcounted()

On 28/08/14 16:13, Chen Gang wrote:
> evtchn_make_refcounted() may return failure, so need process the failure
> case. In failure case, it need call unbind_from_irqhandler() just like
> evtchn_unbind_from_user() has done.
> 
> irq_from_evtchn() must be OK when bind_evtchn_to_irqhandler() succeed,
> so need not check it again.
> 
> Also still need remain the closing port code, because when the failure
> occurs, unbind_from_irqhandler() will not close port internally.

None of the evtchn_make_refcounted() failures can occur since we know we
have a valid irq and info at the single call site.

I would like to see this fixed by refactoring the code to remove
evtchn_make_refcounted() by making all irqs for event channels reference
counted.  These no need for this refcounting to be optional.

David

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