| Message ID | 1363110519.2780.15.camel@bwh-desktop.uk.solarflarecom.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
diff --git a/drivers/net/ethernet/sfc/nic.c b/drivers/net/ethernet/sfc/nic.c index 0ad790c..eaa8e87 100644 --- a/drivers/net/ethernet/sfc/nic.c +++ b/drivers/net/ethernet/sfc/nic.c @@ -376,7 +376,8 @@ efx_may_push_tx_desc(struct efx_tx_queue *tx_queue, unsigned int write_count) return false; tx_queue->empty_read_count = 0; - return ((empty_read_count ^ write_count) & ~EFX_EMPTY_COUNT_VALID) == 0; + return ((empty_read_count ^ write_count) & ~EFX_EMPTY_COUNT_VALID) == 0 + && tx_queue->write_count - write_count == 1; } /* For each entry inserted into the software descriptor ring, create a
Using TX push when notifying the NIC of multiple new descriptors in the ring will very occasionally cause the TX DMA engine to re-use an old descriptor. This can result in a duplicated or partly duplicated packet (new headers with old data), or an IOMMU page fault. This does not happen when the pushed descriptor is the only one written. TX push also provides little latency benefit when a packet requires more than one descriptor. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> --- drivers/net/ethernet/sfc/nic.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-)