On 12/01/16 18:27, Will Deacon wrote:
On Thu, Dec 17, 2015 at 08:50:59PM +0000, Robin Murphy wrote:
In certain unmapping situations it is quite possible to end up issuing
back-to-back TLB synchronisations, which at best is a waste of time and
effort, and at worst causes some hardware to get rather confused. Whilst
the pagetable implementations, or the IOMMU drivers, or both, could keep
track of things to avoid this happening, it seems to make the most sense
to prevent code duplication and add some simple state tracking in the
common interface between the two.
Signed-off-by: Robin Murphy <[email protected]>
---
drivers/iommu/io-pgtable.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/io-pgtable.h b/drivers/iommu/io-pgtable.h
index 95c5565..d06219b 100644
--- a/drivers/iommu/io-pgtable.h
+++ b/drivers/iommu/io-pgtable.h
@@ -132,12 +132,14 @@ void free_io_pgtable_ops(struct io_pgtable_ops *ops);
* @fmt: The page table format.
* @cookie: An opaque token provided by the IOMMU driver and passed back to
* any callback routines.
+ * @sync_flag: Private flag for optimising out redundant syncs.
It makes sense to factor this out like you're proposing, but maybe we
can think of a better name? How about "tlb_sync_pending", to follow
"tlb_flush_pending" in the core code?
Ooh, tlb_flush_pending is a much nicer name indeed. It's almost as if I
threw this together in a pre-holiday rush and put very little thought
into it...
I've fixed it up locally, but I'll save the repost until after -rc1,
especially in case Yong has any further comments in the meantime.
Thanks,
Robin.
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