From: Sowmini Varadhan <sowmini.varadhan@xxxxxxxxxx>
Subject: 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 <sowmini.varadhan@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/iommu-common.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff -puN lib/iommu-common.c~iommu-common-do-not-try-to-deref-a-null-iommu-lazy_flush-pointer-when-n-pool-hint lib/iommu-common.c
--- a/lib/iommu-common.c~iommu-common-do-not-try-to-deref-a-null-iommu-lazy_flush-pointer-when-n-pool-hint
+++ a/lib/iommu-common.c
@@ -21,8 +21,7 @@ static DEFINE_PER_CPU(unsigned int, iomm
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(stru
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);
}
_
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