Messages in this thread | | | Date | Fri, 30 Jul 2010 09:19:40 -0600 | From | Chris Friesen <> | Subject | where are the memory barriers in net driver rx DMA operations? |
| |
Documentation/DMA-API-HOWTO.txt says that memory barriers are still required when accessing consistent mappings. The example they give is for reordering stores to consistent memory but I assume this also applies to reordering loads.
However, I see many net drivers accessing the descriptor ring (in consistent memory), checking the status bit for the buffer, then calling dma_unmap_single() and accessing the data without any explicit memory barrier. Does the unmapping call act as a barrier in this case?
Thanks,
Chris
-- Chris Friesen Software Developer GENBAND chris.friesen@genband.com www.genband.com
| |