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Subject[RFC PATCH 3/5] ixgbe: Add support for ndo_ll_poll
Date
Add the ixgbe driver code implementing ndo_ll_poll.
It should be easy for other drivers to do something similar
in order to enable support for CONFIG_INET_LL_RX_POLL

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
---

drivers/net/ethernet/intel/ixgbe/ixgbe.h | 96 +++++++++++++++++++++++++
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 65 +++++++++++++++--
2 files changed, 152 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
index a8e10cf..71e7a28 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
@@ -356,9 +356,105 @@ struct ixgbe_q_vector {
struct rcu_head rcu; /* to avoid race with update stats on free */
char name[IFNAMSIZ + 9];

+#ifdef CONFIG_INET_LL_RX_POLL
+ unsigned int state;
+#define IXGBE_QV_STATE_IDLE 0
+#define IXGBE_QV_STATE_NAPI 1 /* NAPI owns this QV */
+#define IXGBE_QV_STATE_POLL 2 /* poll owns this QV */
+#define IXGBE_QV_LOCKED (IXGBE_QV_STATE_NAPI | IXGBE_QV_STATE_POLL)
+#define IXGBE_QV_STATE_NAPI_YIELD 4 /* NAPI yielded this QV */
+#define IXGBE_QV_STATE_POLL_YIELD 8 /* poll yielded this QV */
+#define IXGBE_QV_YIELD (IXGBE_QV_STATE_NAPI_YIELD | IXGBE_QV_STATE_POLL_YIELD)
+#define IXGBE_QV_USER_PEND (IXGBE_QV_STATE_POLL | IXGBE_QV_STATE_POLL_YIELD)
+ spinlock_t lock;
+#endif /* CONFIG_INET_LL_RX_POLL */
+
/* for dynamic allocation of rings associated with this q_vector */
struct ixgbe_ring ring[0] ____cacheline_internodealigned_in_smp;
};
+#ifdef CONFIG_INET_LL_RX_POLL
+static inline void ixgbe_qv_init_lock(struct ixgbe_q_vector *q_vector)
+{
+
+ spin_lock_init(&q_vector->lock);
+ q_vector->state = IXGBE_QV_STATE_IDLE;
+}
+
+/* called from the device poll rutine to get ownership of a q_vector */
+static inline int ixgbe_qv_lock_napi(struct ixgbe_q_vector *q_vector)
+{
+ int rc = true;
+ spin_lock(&q_vector->lock);
+ if (q_vector->state & IXGBE_QV_LOCKED) {
+ WARN_ON(q_vector->state & IXGBE_QV_STATE_NAPI);
+ q_vector->state |= IXGBE_QV_STATE_NAPI_YIELD;
+ rc = false;
+ } else
+ /* we don't care if someone yielded */
+ q_vector->state = IXGBE_QV_STATE_NAPI;
+ spin_unlock(&q_vector->lock);
+ return rc;
+}
+
+/* returns true is someone tried to get the qv while napi had it */
+static inline int ixgbe_qv_unlock_napi(struct ixgbe_q_vector *q_vector)
+{
+ int rc = false;
+ spin_lock(&q_vector->lock);
+ WARN_ON(q_vector->state & (IXGBE_QV_STATE_POLL |
+ IXGBE_QV_STATE_NAPI_YIELD));
+
+ if (q_vector->state & IXGBE_QV_STATE_POLL_YIELD)
+ rc = true;
+ q_vector->state = IXGBE_QV_STATE_IDLE;
+ spin_unlock(&q_vector->lock);
+ return rc;
+}
+
+/* called from ixgbe_low_latency_poll() */
+static inline int ixgbe_qv_lock_poll(struct ixgbe_q_vector *q_vector)
+{
+ int rc = true;
+ spin_lock_bh(&q_vector->lock);
+ if ((q_vector->state & IXGBE_QV_LOCKED)) {
+ q_vector->state |= IXGBE_QV_STATE_POLL_YIELD;
+ rc = false;
+ } else
+ /* preserve yield marks */
+ q_vector->state |= IXGBE_QV_STATE_POLL;
+ spin_unlock_bh(&q_vector->lock);
+ return rc;
+}
+
+/* returns true if someone tried to get the qv while it was locked */
+static inline int ixgbe_qv_unlock_poll(struct ixgbe_q_vector *q_vector)
+{
+ int rc = false;
+ spin_lock_bh(&q_vector->lock);
+ WARN_ON(q_vector->state & (IXGBE_QV_STATE_NAPI));
+
+ if (q_vector->state & IXGBE_QV_STATE_POLL_YIELD)
+ rc = true;
+ q_vector->state = IXGBE_QV_STATE_IDLE;
+ spin_unlock_bh(&q_vector->lock);
+ return rc;
+}
+
+/* true if a socket is polling, even if it did not get the lock */
+static inline int ixgbe_qv_ll_polling(struct ixgbe_q_vector *q_vector)
+{
+ WARN_ON(!(q_vector->state & IXGBE_QV_LOCKED));
+ return q_vector->state & IXGBE_QV_USER_PEND;
+}
+#else
+#define ixgbe_qv_init_lock(qv) do {} while (0)
+#define ixgbe_qv_lock_napi(qv) 1
+#define ixgbe_qv_unlock_napi(qv) 0
+#define ixgbe_qv_lock_poll(qv) 0
+#define ixgbe_qv_unlock_poll(qv) 0
+#define ixgbe_qv_ll_polling(qv) 0
+#endif /* CONFIG_INET_LL_RX_POLL */
+
#ifdef CONFIG_IXGBE_HWMON

#define IXGBE_HWMON_TYPE_LOC 0
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 68478d6..903bbc0 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -47,6 +47,7 @@
#include <linux/if_bridge.h>
#include <linux/prefetch.h>
#include <scsi/fc/fc_fcoe.h>
+#include <net/ll_poll.h>

#include "ixgbe.h"
#include "ixgbe_common.h"
@@ -1458,7 +1459,9 @@ static void ixgbe_rx_skb(struct ixgbe_q_vector *q_vector,
{
struct ixgbe_adapter *adapter = q_vector->adapter;

- if (!(adapter->flags & IXGBE_FLAG_IN_NETPOLL))
+ if (ixgbe_qv_ll_polling(q_vector))
+ netif_receive_skb(skb);
+ else if (!(adapter->flags & IXGBE_FLAG_IN_NETPOLL))
napi_gro_receive(&q_vector->napi, skb);
else
netif_rx(skb);
@@ -1846,9 +1849,9 @@ dma_sync:
* expensive overhead for IOMMU access this provides a means of avoiding
* it by maintaining the mapping of the page to the syste.
*
- * Returns true if all work is completed without reaching budget
+ * Returns amount of work completed
**/
-static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
+static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
struct ixgbe_ring *rx_ring,
const int budget)
{
@@ -1930,6 +1933,7 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
}

#endif /* IXGBE_FCOE */
+ skb_mark_ll(&q_vector->napi, skb);
ixgbe_rx_skb(q_vector, skb);

/* update budget accounting */
@@ -1946,9 +1950,37 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
if (cleaned_count)
ixgbe_alloc_rx_buffers(rx_ring, cleaned_count);

- return (total_rx_packets < budget);
+ return total_rx_packets;
}

+#ifdef CONFIG_INET_LL_RX_POLL
+/* must be called with local_bh_disable()d */
+static int ixgbe_low_latency_recv(struct napi_struct *napi)
+{
+ struct ixgbe_q_vector *q_vector =
+ container_of(napi, struct ixgbe_q_vector, napi);
+ struct ixgbe_adapter *adapter = q_vector->adapter;
+ struct ixgbe_ring *ring;
+ int found;
+
+ if (test_bit(__IXGBE_DOWN, &adapter->state))
+ return LL_FLUSH_FAILED;
+
+ if (!ixgbe_qv_lock_poll(q_vector))
+ return LL_FLUSH_BUSY;
+
+ ixgbe_for_each_ring(ring, q_vector->rx) {
+ found = ixgbe_clean_rx_irq(q_vector, ring, 4);
+ if (found)
+ break;
+ }
+
+ ixgbe_qv_unlock_poll(q_vector);
+
+ return LL_FLUSH_DONE;
+}
+#endif /* CONFIG_INET_LL_RX_POLL */
+
/**
* ixgbe_configure_msix - Configure MSI-X hardware
* @adapter: board private structure
@@ -2491,6 +2523,9 @@ int ixgbe_poll(struct napi_struct *napi, int budget)
ixgbe_for_each_ring(ring, q_vector->tx)
clean_complete &= !!ixgbe_clean_tx_irq(q_vector, ring);

+ if (!ixgbe_qv_lock_napi(q_vector))
+ return budget;
+
/* attempt to distribute budget to each queue fairly, but don't allow
* the budget to go below 1 because we'll exit polling */
if (q_vector->rx.count > 1)
@@ -2499,11 +2534,11 @@ int ixgbe_poll(struct napi_struct *napi, int budget)
per_ring_budget = budget;

ixgbe_for_each_ring(ring, q_vector->rx)
- clean_complete &= ixgbe_clean_rx_irq(q_vector, ring,
- per_ring_budget);
+ clean_complete &= (ixgbe_clean_rx_irq(q_vector, ring,
+ per_ring_budget) < per_ring_budget);

/* If all work not completed, return budget and keep polling */
- if (!clean_complete)
+ if (ixgbe_qv_unlock_napi(q_vector) || !clean_complete)
return budget;

/* all work done, exit the polling mode */
@@ -3686,16 +3721,25 @@ static void ixgbe_napi_enable_all(struct ixgbe_adapter *adapter)
{
int q_idx;

- for (q_idx = 0; q_idx < adapter->num_q_vectors; q_idx++)
+ for (q_idx = 0; q_idx < adapter->num_q_vectors; q_idx++) {
+ ixgbe_qv_init_lock(adapter->q_vector[q_idx]);
napi_enable(&adapter->q_vector[q_idx]->napi);
+ }
}

static void ixgbe_napi_disable_all(struct ixgbe_adapter *adapter)
{
int q_idx;

- for (q_idx = 0; q_idx < adapter->num_q_vectors; q_idx++)
+ local_bh_disable(); /* for ixgbe_qv_lock_napi() */
+ for (q_idx = 0; q_idx < adapter->num_q_vectors; q_idx++) {
napi_disable(&adapter->q_vector[q_idx]->napi);
+ while (!ixgbe_qv_lock_napi(adapter->q_vector[q_idx])) {
+ pr_info("QV %d locked\n", q_idx);
+ msleep(1);
+ }
+ }
+ local_bh_enable();
}

#ifdef CONFIG_IXGBE_DCB
@@ -7159,6 +7203,9 @@ static const struct net_device_ops ixgbe_netdev_ops = {
#ifdef CONFIG_NET_POLL_CONTROLLER
.ndo_poll_controller = ixgbe_netpoll,
#endif
+#ifdef CONFIG_INET_LL_RX_POLL
+ .ndo_ll_poll = ixgbe_low_latency_recv,
+#endif
#ifdef IXGBE_FCOE
.ndo_fcoe_ddp_setup = ixgbe_fcoe_ddp_get,
.ndo_fcoe_ddp_target = ixgbe_fcoe_ddp_target,


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