Re: [PATCH 5.10 055/101] net: ll_temac: Add memory-barriers for TX BD access

Hi!

Add a couple of memory-barriers to ensure correct ordering of read/write access to TX BDs.

So... this is dealing with CPU-to-device consistency, not CPU-to-CPU, right?

+++ b/drivers/net/ethernet/xilinx/ll_temac_main.c @@ -774,12 +774,15 @@ static void temac_start_xmit_done(struct net_device *ndev) stat = be32_to_cpu(cur_p->app0); while (stat & STS_CTRL_APP0_CMPLT) {

• /* Make sure that the other fields are read after bd is
  

•  * released by dma
  

•  */
  

• rmb();
  

  dma_unmap_single(ndev->dev.parent,

Full barrier, as expected.

@@ -788,6 +791,12 @@ static void temac_start_xmit_done(struct net_device *ndev) ndev->stats.tx_packets++; ndev->stats.tx_bytes += be32_to_cpu(cur_p->len);

• /* app0 must be visible last, as it is used to flag
  

•  * availability of the bd
  

•  */
  

• smp_mb();
  

SMP-only barrier, but full barrier is needed here AFAICT.

Pavel