Re: [PATCH v4 06/17] octeontx2-pf: Receive packet handling support

On Tue, Jan 21, 2020 at 10:03 PM Jakub Kicinski [off-list ref] wrote:

On Tue, 21 Jan 2020 18:51:40 +0530, sunil.kovvuri@gmail.com wrote:

quoted

 static int otx2_rx_napi_handler(struct otx2_nic *pfvf,
                              struct napi_struct *napi,
                              struct otx2_cq_queue *cq, int budget)

quoted

+     int processed_cqe = 0;
+     s64 bufptr;
+
+     /* Make sure HW writes to CQ are done */
+     dma_rmb();

What is this memory barrier between?

Usually dma_rmb() barrier is placed between accesses to the part of the
descriptor which tells us device is done and the rest of descriptor
accesses.

Will recheck, i think this can be removed.
Previously the logic was different and used to read number of valid
descriptor count from HW
and a barrier between that and descriptor processing was needed.

Thanks,
Sunil.