From d046b770c9fc36ccb19c27afdb8322220108cbc7 Mon Sep 17 00:00:00 2001 From: Sowmini Varadhan Date: Tue, 22 Sep 2015 14:59:20 -0700 Subject: [PATCH] lib/iommu-common.c: 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. I had a sparc kernel that was crashing when I was trying to process some very large perf.data files- the crash happens when the scsi driver calls into dma_4v_map_sg and thus the iommu_tbl_range_alloc(). Signed-off-by: Sowmini Varadhan Cc: Benjamin Herrenschmidt Cc: Guenter Roeck Cc: David S. Miller Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/iommu-common.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/lib/iommu-common.c b/lib/iommu-common.c index ff19f66d3f7f..b1c93e94ca7a 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); }