[PATCH net 1/2] ibmvnic: Ensure that SCRQ entry reads are correctly ordered
From: Thomas Falcon <hidden>
Date: 2020-11-24 17:30:14
Also in:
linuxppc-dev
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, Michael Ellerman, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Ensure that received Subordinate Command-Response Queue (SCRQ)
entries are properly read in order by the driver. These queues
are used in the ibmvnic device to process RX buffer and TX completion
descriptors. dma_rmb barriers have been added after checking for a
pending descriptor to ensure the correct descriptor entry is checked
and after reading the SCRQ descriptor to ensure the entire
descriptor is read before processing.
Fixes: 032c5e828 ("Driver for IBM System i/p VNIC protocol")
Signed-off-by: Thomas Falcon <redacted>
---
drivers/net/ethernet/ibm/ibmvnic.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 2aa40b2..489ed5e 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c@@ -2403,6 +2403,8 @@ static int ibmvnic_poll(struct napi_struct *napi, int budget) if (!pending_scrq(adapter, adapter->rx_scrq[scrq_num])) break; + /* ensure that we do not prematurely exit the polling loop */ + dma_rmb(); next = ibmvnic_next_scrq(adapter, adapter->rx_scrq[scrq_num]); rx_buff = (struct ibmvnic_rx_buff *)be64_to_cpu(next->
@@ -3098,6 +3100,9 @@ static int ibmvnic_complete_tx(struct ibmvnic_adapter *adapter, unsigned int pool = scrq->pool_index; int num_entries = 0; + /* ensure that the correct descriptor entry is read */ + dma_rmb(); + next = ibmvnic_next_scrq(adapter, scrq); for (i = 0; i < next->tx_comp.num_comps; i++) { if (next->tx_comp.rcs[i]) {
@@ -3498,6 +3503,9 @@ static union sub_crq *ibmvnic_next_scrq(struct ibmvnic_adapter *adapter, } spin_unlock_irqrestore(&scrq->lock, flags); + /* ensure that the entire SCRQ descriptor is read */ + dma_rmb(); + return entry; }
--
1.8.3.1