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ibmvnic: rework to ensure SCRQ entry reads are properly ordered

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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 <ljp@linux.ibm.com>
Acked-by: Thomas Falcon <tlfalcon@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Lijun Pan 2021-01-29 19:19:04 -06:00 committed by Jakub Kicinski
parent 1a2b60f6f1
commit 665ab1eb18
1 changed files with 11 additions and 19 deletions
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30
drivers/net/ethernet/ibm/ibmvnic.c
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@ -2444,12 +2444,6 @@ restart_poll:
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 @@ restart_loop:
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();