This is a note to let you know that I've just added the patch titled
net: ena: Wrong missing IO completions check order
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-ena-wrong-missing-io-completions-check-order.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c01fb83542af435de8945928b1820e2d999d92d8
Author: David Arinzon <darinzon@xxxxxxxxxx>
Date: Wed Apr 10 09:13:56 2024 +0000
net: ena: Wrong missing IO completions check order
[ Upstream commit f7e417180665234fdb7af2ebe33d89aaa434d16f ]
Missing IO completions check is called every second (HZ jiffies).
This commit fixes several issues with this check:
1. Duplicate queues check:
Max of 4 queues are scanned on each check due to monitor budget.
Once reaching the budget, this check exits under the assumption that
the next check will continue to scan the remainder of the queues,
but in practice, next check will first scan the last already scanned
queue which is not necessary and may cause the full queue scan to
last a couple of seconds longer.
The fix is to start every check with the next queue to scan.
For example, on 8 IO queues:
Bug: [0,1,2,3], [3,4,5,6], [6,7]
Fix: [0,1,2,3], [4,5,6,7]
2. Unbalanced queues check:
In case the number of active IO queues is not a multiple of budget,
there will be checks which don't utilize the full budget
because the full scan exits when reaching the last queue id.
The fix is to run every TX completion check with exact queue budget
regardless of the queue id.
For example, on 7 IO queues:
Bug: [0,1,2,3], [4,5,6], [0,1,2,3]
Fix: [0,1,2,3], [4,5,6,0], [1,2,3,4]
The budget may be lowered in case the number of IO queues is less
than the budget (4) to make sure there are no duplicate queues on
the same check.
For example, on 3 IO queues:
Bug: [0,1,2,0], [1,2,0,1]
Fix: [0,1,2], [0,1,2]
Fixes: 1738cd3ed342 ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Amit Bernstein <amitbern@xxxxxxxxxx>
Signed-off-by: David Arinzon <darinzon@xxxxxxxxxx>
Reviewed-by: Shannon Nelson <shannon.nelson@xxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
index 43c099141e211..44b8df731c889 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -3815,10 +3815,11 @@ static void check_for_missing_completions(struct ena_adapter *adapter)
{
struct ena_ring *tx_ring;
struct ena_ring *rx_ring;
- int i, budget, rc;
+ int qid, budget, rc;
int io_queue_count;
io_queue_count = adapter->xdp_num_queues + adapter->num_io_queues;
+
/* Make sure the driver doesn't turn the device in other process */
smp_rmb();
@@ -3831,27 +3832,29 @@ static void check_for_missing_completions(struct ena_adapter *adapter)
if (adapter->missing_tx_completion_to == ENA_HW_HINTS_NO_TIMEOUT)
return;
- budget = ENA_MONITORED_TX_QUEUES;
+ budget = min_t(u32, io_queue_count, ENA_MONITORED_TX_QUEUES);
- for (i = adapter->last_monitored_tx_qid; i < io_queue_count; i++) {
- tx_ring = &adapter->tx_ring[i];
- rx_ring = &adapter->rx_ring[i];
+ qid = adapter->last_monitored_tx_qid;
+
+ while (budget) {
+ qid = (qid + 1) % io_queue_count;
+
+ tx_ring = &adapter->tx_ring[qid];
+ rx_ring = &adapter->rx_ring[qid];
rc = check_missing_comp_in_tx_queue(adapter, tx_ring);
if (unlikely(rc))
return;
- rc = !ENA_IS_XDP_INDEX(adapter, i) ?
+ rc = !ENA_IS_XDP_INDEX(adapter, qid) ?
check_for_rx_interrupt_queue(adapter, rx_ring) : 0;
if (unlikely(rc))
return;
budget--;
- if (!budget)
- break;
}
- adapter->last_monitored_tx_qid = i % io_queue_count;
+ adapter->last_monitored_tx_qid = qid;
}
/* trigger napi schedule after 2 consecutive detections */
