linux-kernel - [PATCH] iommu-common: Do not try to deref a null iommu->lazy

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Message-ID: <20150917015043.GC13020@oracle.com>
Date:	Wed, 16 Sep 2015 21:50:43 -0400
From:	Sowmini Varadhan <sowmini.varadhan@...cle.com>
To:	linux-kernel@...r.kernel.org
Cc:	sowmini.varadhan@...cle.com, benh@...nel.crashing.org,
	akpm@...ux-foundation.org, linux@...ck-us.net, davem@...emloft.net
Subject: [PATCH] iommu-common: Do not try to deref a null iommu->lazy_flush()
 pointer when n < pool->hint

The check for invoking iommu->lazy_flush() from iommu_tbl_range_alloc()
has to be refactored so that we only call ->lazy_flush() if it is non-null.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
---
 lib/iommu-common.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/iommu-common.c b/lib/iommu-common.c
index ff19f66..b1c93e9 100644
--- a/lib/iommu-common.c
+++ b/lib/iommu-common.c
@@ -21,8 +21,7 @@ static	DEFINE_PER_CPU(unsigned int, iommu_hash_common);
 
 static inline bool need_flush(struct iommu_map_table *iommu)
 {
-	return (iommu->lazy_flush != NULL &&
-		(iommu->flags & IOMMU_NEED_FLUSH) != 0);
+	return ((iommu->flags & IOMMU_NEED_FLUSH) != 0);
 }
 
 static inline void set_flush(struct iommu_map_table *iommu)
@@ -211,7 +210,8 @@ unsigned long iommu_tbl_range_alloc(struct device *dev,
 			goto bail;
 		}
 	}
-	if (n < pool->hint || need_flush(iommu)) {
+	if (iommu->lazy_flush &&
+	    (n < pool->hint || need_flush(iommu))) {
 		clear_flush(iommu);
 		iommu->lazy_flush(iommu);
 	}
-- 
1.7.1

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