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ibmvnic: Ensure that SCRQ entry reads are correctly ordered

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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: 032c5e8284 ("Driver for IBM System i/p VNIC protocol")
Signed-off-by: Thomas Falcon <tlfalcon@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Thomas Falcon 2020-12-01 09:52:10 -06:00 committed by David S. Miller
parent 237f977ab9
commit b71ec95223
1 changed files with 18 additions and 0 deletions
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18
drivers/net/ethernet/ibm/ibmvnic.c
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@ -2404,6 +2404,12 @@ restart_poll:
if (!pending_scrq(adapter, adapter->rx_scrq[scrq_num])) if (!pending_scrq(adapter, adapter->rx_scrq[scrq_num]))
break; 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, adapter->rx_scrq[scrq_num]); next = ibmvnic_next_scrq(adapter, adapter->rx_scrq[scrq_num]);
rx_buff = rx_buff =
(struct ibmvnic_rx_buff *)be64_to_cpu(next-> (struct ibmvnic_rx_buff *)be64_to_cpu(next->
@ -3113,6 +3119,13 @@ restart_loop:
unsigned int pool = scrq->pool_index; unsigned int pool = scrq->pool_index;
int num_entries = 0; int num_entries = 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); next = ibmvnic_next_scrq(adapter, scrq);
for (i = 0; i < next->tx_comp.num_comps; i++) { for (i = 0; i < next->tx_comp.num_comps; i++) {
if (next->tx_comp.rcs[i]) { if (next->tx_comp.rcs[i]) {
@ -3513,6 +3526,11 @@ static union sub_crq *ibmvnic_next_scrq(struct ibmvnic_adapter *adapter,
} }
spin_unlock_irqrestore(&scrq->lock, flags); spin_unlock_irqrestore(&scrq->lock, flags);
/* Ensure that the entire buffer descriptor has been
* loaded before reading its contents
*/
dma_rmb();
return entry; return entry;
} }