linux-kernel - [PATCH 2/3] vfio: Ignore sprurious notifies

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Message-ID: <20130611160148.9995.96816.stgit@bling.home>
Date:	Tue, 11 Jun 2013 10:01:48 -0600
From:	Alex Williamson <alex.williamson@...hat.com>
To:	alex.williamson@...hat.com
Cc:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: [PATCH 2/3] vfio: Ignore sprurious notifies

Remove debugging WARN_ON if we get a spurious notify for a group that
no longer exists.  No reports of anyone hitting this, but it would
likely be a race and not a bug if they did.

Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
---
 drivers/vfio/vfio.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 1bed313..2edfecc 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -508,13 +508,11 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb,
 	struct device *dev = data;
 
 	/*
-	 * Need to go through a group_lock lookup to get a reference or
-	 * we risk racing a group being removed.  Leave a WARN_ON for
-	 * debuging, but if the group no longer exists, a spurious notify
-	 * is harmless.
+	 * Need to go through a group_lock lookup to get a reference or we
+	 * risk racing a group being removed.  Ignore spurious notifies.
 	 */
 	group = vfio_group_try_get(group);
-	if (WARN_ON(!group))
+	if (!group)
 		return NOTIFY_OK;
 
 	switch (action) {

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