sfc: limit ARFS workitems in flight per channel
A misconfigured system (e.g. with all interrupts affinitised to all CPUs)
may produce a storm of ARFS steering events. With the existing sfc ARFS
implementation, that could create a backlog of workitems that grinds the
system to a halt. To prevent this, limit the number of workitems that
may be in flight for a given SFC device to 8 (EFX_RPS_MAX_IN_FLIGHT), and
return EBUSY from our ndo_rx_flow_steer method if the limit is reached.
Given this limit, also store the workitems in an array of slots within the
struct efx_nic, rather than dynamically allocating for each request.
The limit should not negatively impact performance, because it is only
likely to be hit in cases where ARFS will be ineffective anyway.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c
index 13b0eb7..9c593c6 100644
--- a/drivers/net/ethernet/sfc/rx.c
+++ b/drivers/net/ethernet/sfc/rx.c
@@ -827,28 +827,13 @@
#ifdef CONFIG_RFS_ACCEL
-/**
- * struct efx_async_filter_insertion - Request to asynchronously insert a filter
- * @net_dev: Reference to the netdevice
- * @spec: The filter to insert
- * @work: Workitem for this request
- * @rxq_index: Identifies the channel for which this request was made
- * @flow_id: Identifies the kernel-side flow for which this request was made
- */
-struct efx_async_filter_insertion {
- struct net_device *net_dev;
- struct efx_filter_spec spec;
- struct work_struct work;
- u16 rxq_index;
- u32 flow_id;
-};
-
static void efx_filter_rfs_work(struct work_struct *data)
{
struct efx_async_filter_insertion *req = container_of(data, struct efx_async_filter_insertion,
work);
struct efx_nic *efx = netdev_priv(req->net_dev);
struct efx_channel *channel = efx_get_channel(efx, req->rxq_index);
+ int slot_idx = req - efx->rps_slot;
int rc;
rc = efx->type->filter_insert(efx, &req->spec, true);
@@ -878,8 +863,8 @@
}
/* Release references */
+ clear_bit(slot_idx, &efx->rps_slot_map);
dev_put(req->net_dev);
- kfree(req);
}
int efx_filter_rfs(struct net_device *net_dev, const struct sk_buff *skb,
@@ -888,22 +873,36 @@
struct efx_nic *efx = netdev_priv(net_dev);
struct efx_async_filter_insertion *req;
struct flow_keys fk;
+ int slot_idx;
+ int rc;
- if (flow_id == RPS_FLOW_ID_INVALID)
- return -EINVAL;
+ /* find a free slot */
+ for (slot_idx = 0; slot_idx < EFX_RPS_MAX_IN_FLIGHT; slot_idx++)
+ if (!test_and_set_bit(slot_idx, &efx->rps_slot_map))
+ break;
+ if (slot_idx >= EFX_RPS_MAX_IN_FLIGHT)
+ return -EBUSY;
- if (!skb_flow_dissect_flow_keys(skb, &fk, 0))
- return -EPROTONOSUPPORT;
+ if (flow_id == RPS_FLOW_ID_INVALID) {
+ rc = -EINVAL;
+ goto out_clear;
+ }
- if (fk.basic.n_proto != htons(ETH_P_IP) && fk.basic.n_proto != htons(ETH_P_IPV6))
- return -EPROTONOSUPPORT;
- if (fk.control.flags & FLOW_DIS_IS_FRAGMENT)
- return -EPROTONOSUPPORT;
+ if (!skb_flow_dissect_flow_keys(skb, &fk, 0)) {
+ rc = -EPROTONOSUPPORT;
+ goto out_clear;
+ }
- req = kmalloc(sizeof(*req), GFP_ATOMIC);
- if (!req)
- return -ENOMEM;
+ if (fk.basic.n_proto != htons(ETH_P_IP) && fk.basic.n_proto != htons(ETH_P_IPV6)) {
+ rc = -EPROTONOSUPPORT;
+ goto out_clear;
+ }
+ if (fk.control.flags & FLOW_DIS_IS_FRAGMENT) {
+ rc = -EPROTONOSUPPORT;
+ goto out_clear;
+ }
+ req = efx->rps_slot + slot_idx;
efx_filter_init_rx(&req->spec, EFX_FILTER_PRI_HINT,
efx->rx_scatter ? EFX_FILTER_FLAG_RX_SCATTER : 0,
rxq_index);
@@ -933,6 +932,9 @@
req->flow_id = flow_id;
schedule_work(&req->work);
return 0;
+out_clear:
+ clear_bit(slot_idx, &efx->rps_slot_map);
+ return rc;
}
bool __efx_filter_rfs_expire(struct efx_nic *efx, unsigned int quota)