[PATCH net-next v2 1/2] ibmvnic: rework to ensure SCRQ entry reads are properly ordered
From: Lijun Pan <hidden>
Date: 2021-01-30 01:24:54
Subsystem:
ibm power sriov virtual nic device driver, linux for powerpc (32-bit and 64-bit), networking drivers, the rest · Maintainers:
Haren Myneni, Rick Lindsley, Madhavan Srinivasan, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Move the dma_rmb() between pending_scrq() and ibmvnic_next_scrq() into the end of pending_scrq() to save the duplicated code since this dma_rmb will be used 3 times. Signed-off-by: Lijun Pan <redacted> Acked-by: Thomas Falcon <redacted> --- drivers/net/ethernet/ibm/ibmvnic.c | 30 +++++++++++------------------- 1 file changed, 11 insertions(+), 19 deletions(-)
diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index a40af510018a..331ebca2f57a 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c@@ -2444,12 +2444,6 @@ static int ibmvnic_poll(struct napi_struct *napi, int budget) if (!pending_scrq(adapter, rx_scrq)) break; - /* The queue entry at the current index is peeked at above - * to determine that there is a valid descriptor awaiting - * processing. We want to be sure that the current slot - * holds a valid descriptor before reading its contents. - */ - dma_rmb(); next = ibmvnic_next_scrq(adapter, rx_scrq); rx_buff = (struct ibmvnic_rx_buff *)be64_to_cpu(next->
@@ -3189,13 +3183,6 @@ static int ibmvnic_complete_tx(struct ibmvnic_adapter *adapter, int total_bytes = 0; int num_packets = 0; - /* The queue entry at the current index is peeked at above - * to determine that there is a valid descriptor awaiting - * processing. We want to be sure that the current slot - * holds a valid descriptor before reading its contents. - */ - dma_rmb(); - next = ibmvnic_next_scrq(adapter, scrq); for (i = 0; i < next->tx_comp.num_comps; i++) { if (next->tx_comp.rcs[i])
@@ -3569,11 +3556,16 @@ static int pending_scrq(struct ibmvnic_adapter *adapter, struct ibmvnic_sub_crq_queue *scrq) { union sub_crq *entry = &scrq->msgs[scrq->cur]; + int rc; - if (entry->generic.first & IBMVNIC_CRQ_CMD_RSP) - return 1; - else - return 0; + rc = !!(entry->generic.first & IBMVNIC_CRQ_CMD_RSP); + + /* Ensure that the SCRQ valid flag is loaded prior to loading the + * contents of the SCRQ descriptor + */ + dma_rmb(); + + return rc; } static union sub_crq *ibmvnic_next_scrq(struct ibmvnic_adapter *adapter,
@@ -3592,8 +3584,8 @@ static union sub_crq *ibmvnic_next_scrq(struct ibmvnic_adapter *adapter, } spin_unlock_irqrestore(&scrq->lock, flags); - /* Ensure that the entire buffer descriptor has been - * loaded before reading its contents + /* Ensure that the SCRQ valid flag is loaded prior to loading the + * contents of the SCRQ descriptor */ dma_rmb();
--
2.23.0