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From: Joerg Roedel <joro@8bytes.org>
To: Greg Edwards <gedwards@ddn.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] iommu/vt-d: race setting IRQ CPU affinity while freeing IRQ
Date: Tue, 29 Jul 2014 12:45:31 +0200	[thread overview]
Message-ID: <20140729104531.GB9809@8bytes.org> (raw)
In-Reply-To: <20140723161326.GB32422@psuche.datadirectnet.com>

On Wed, Jul 23, 2014 at 10:13:26AM -0600, Greg Edwards wrote:
> A user process setting the CPU affinity of an IRQ for a KVM
> direct-assigned device via /proc/irq/<IRQ#>/smp_affinity can race with
> the IRQ being released by QEMU, resulting in a NULL iommu pointer
> dereference in get_irte().

Maybe I wasn't clear enough, what I am missing is a panic message with a
backtrace from the NULL pointer deref you are seeing in the commit
message.

Also I am still wondering why it is possible to set affinity from
userspace while the irq is about to be freed. Shouldn't the proc files
are already unregistered when the irq is freed?


	Joerg


WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: Greg Edwards <gedwards-LfVdkaOWEx8@public.gmane.org>
Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	David Woodhouse <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH v2] iommu/vt-d: race setting IRQ CPU affinity while freeing IRQ
Date: Tue, 29 Jul 2014 12:45:31 +0200	[thread overview]
Message-ID: <20140729104531.GB9809@8bytes.org> (raw)
In-Reply-To: <20140723161326.GB32422-+5IcJesBrg1QnCaYh1JbbuXjVpU8mP+x@public.gmane.org>

On Wed, Jul 23, 2014 at 10:13:26AM -0600, Greg Edwards wrote:
> A user process setting the CPU affinity of an IRQ for a KVM
> direct-assigned device via /proc/irq/<IRQ#>/smp_affinity can race with
> the IRQ being released by QEMU, resulting in a NULL iommu pointer
> dereference in get_irte().

Maybe I wasn't clear enough, what I am missing is a panic message with a
backtrace from the NULL pointer deref you are seeing in the commit
message.

Also I am still wondering why it is possible to set affinity from
userspace while the irq is about to be freed. Shouldn't the proc files
are already unregistered when the irq is freed?


	Joerg

  reply	other threads:[~2014-07-29 10:45 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-22 14:27 [PATCH] iommu/vt-d: fix race between free_irte() and get_irte() Greg Edwards
2014-07-22 14:27 ` Greg Edwards
2014-07-23 14:40 ` Joerg Roedel
2014-07-23 14:40   ` Joerg Roedel
2014-07-23 14:49   ` Greg Edwards
2014-07-23 14:49     ` Greg Edwards
2014-07-23 15:10     ` Joerg Roedel
2014-07-23 15:10       ` Joerg Roedel
2014-07-23 16:13       ` [PATCH v2] iommu/vt-d: race setting IRQ CPU affinity while freeing IRQ Greg Edwards
2014-07-23 16:13         ` Greg Edwards
2014-07-29 10:45         ` Joerg Roedel [this message]
2014-07-29 10:45           ` Joerg Roedel
2014-07-29 17:21           ` Greg Edwards
2014-07-29 17:21             ` Greg Edwards
2014-07-31 11:49             ` Joerg Roedel
2014-07-31 11:49               ` Joerg Roedel

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