[PATCH AUTOSEL 5.9 054/147] sfc: add and use efx_tx_send_pending in tx.c

Sasha Levin
2020-10-26T23:50:48Z

From: Edward Cree <ecree@solarflare.com>

[ Upstream commit 1c0544d24927e4fad04f858216b8ea767a3bd123 ]

Instead of using efx_tx_queue_partner(), which relies on the assumption
that tx_queues_per_channel is 2, efx_tx_send_pending() iterates over
txqs with efx_for_each_channel_tx_queue().
We unconditionally set tx_queue->xmit_pending (renamed from
xmit_more_available), then condition on xmit_more for the call to
efx_tx_send_pending(), which will clear xmit_pending. Thus, after an
xmit_more TX, the doorbell is un-rung and xmit_pending is true.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/sfc/ef10.c | 2 +-
drivers/net/ethernet/sfc/ef100_tx.c | 14 +++----
drivers/net/ethernet/sfc/farch.c | 2 +-
drivers/net/ethernet/sfc/net_driver.h | 4 +-
drivers/net/ethernet/sfc/tx.c | 59 ++++++++++++++-------------
drivers/net/ethernet/sfc/tx_common.c | 4 +-
6 files changed, 44 insertions(+), 41 deletions(-)

diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index 4b0b2cf026a52..ad05710883f85 100644
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c
@@ -2367,7 +2367,7 @@ static void efx_ef10_tx_write(struct efx_tx_queue *tx_queue)
unsigned int write_ptr;
efx_qword_t *txd;

- tx_queue->xmit_more_available = false;
+ tx_queue->xmit_pending = false;
if (unlikely(tx_queue->write_count == tx_queue->insert_count))
return;

diff --git a/drivers/net/ethernet/sfc/ef100_tx.c b/drivers/net/ethernet/sfc/ef100_tx.c
index a09546e434085..8d478c5e720e1 100644
--- a/drivers/net/ethernet/sfc/ef100_tx.c
+++ b/drivers/net/ethernet/sfc/ef100_tx.c
@@ -131,7 +131,7 @@ void ef100_notify_tx_desc(struct efx_tx_queue *tx_queue)
efx_writed_page(tx_queue->efx, &reg,
ER_GZ_TX_RING_DOORBELL, tx_queue->queue);
tx_queue->notify_count = tx_queue->write_count;
- tx_queue->xmit_more_available = false;
+ tx_queue->xmit_pending = false;
}

static void ef100_tx_push_buffers(struct efx_tx_queue *tx_queue)
@@ -373,14 +373,14 @@ int ef100_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
}

if (__netdev_tx_sent_queue(tx_queue->core_txq, skb->len, xmit_more))
- tx_queue->xmit_more_available = false; /* push doorbell */
+ tx_queue->xmit_pending = false; /* push doorbell */
else if (tx_queue->write_count - tx_queue->notify_count > 255)
/* Ensure we never push more than 256 packets at once */
- tx_queue->xmit_more_available = false; /* push */
+ tx_queue->xmit_pending = false; /* push */
else
- tx_queue->xmit_more_available = true; /* don't push yet */
+ tx_queue->xmit_pending = true; /* don't push yet */

- if (!tx_queue->xmit_more_available)
+ if (!tx_queue->xmit_pending)
ef100_tx_push_buffers(tx_queue);

if (segments) {
@@ -400,9 +400,9 @@ int ef100_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
/* If we're not expecting another transmit and we had something to push
* on this queue then we need to push here to get the previous packets
* out. We only enter this branch from before the 'Update BQL' section
- * above, so xmit_more_available still refers to the old state.
+ * above, so xmit_pending still refers to the old state.
*/
- if (tx_queue->xmit_more_available && !xmit_more)
+ if (tx_queue->xmit_pending && !xmit_more)
ef100_tx_push_buffers(tx_queue);
return rc;
}
diff --git a/drivers/net/ethernet/sfc/farch.c b/drivers/net/ethernet/sfc/farch.c
index 4002f9a3ae909..0cc7a37b63445 100644
--- a/drivers/net/ethernet/sfc/farch.c
+++ b/drivers/net/ethernet/sfc/farch.c
@@ -320,7 +320,7 @@ void efx_farch_tx_write(struct efx_tx_queue *tx_queue)
unsigned write_ptr;
unsigned old_write_count = tx_queue->write_count;

- tx_queue->xmit_more_available = false;
+ tx_queue->xmit_pending = false;
if (unlikely(tx_queue->write_count == tx_queue->insert_count))
return;

diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 062462a138475..fb7290bbb135c 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -244,7 +244,7 @@ struct efx_tx_buffer {
* @tso_fallbacks: Number of times TSO fallback used
* @pushes: Number of times the TX push feature has been used
* @pio_packets: Number of times the TX PIO feature has been used
- * @xmit_more_available: Are any packets waiting to be pushed to the NIC
+ * @xmit_pending: Are any packets waiting to be pushed to the NIC
* @cb_packets: Number of times the TX copybreak feature has been used
* @notify_count: Count of notified descriptors to the NIC
* @empty_read_count: If the completion path has seen the queue as empty
@@ -292,7 +292,7 @@ struct efx_tx_queue {
unsigned int tso_fallbacks;
unsigned int pushes;
unsigned int pio_packets;
- bool xmit_more_available;
+ bool xmit_pending;
unsigned int cb_packets;
unsigned int notify_count;
/* Statistics to supplement MAC stats */
diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index 727201d5eb24e..c502d226371a9 100644
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -268,6 +268,19 @@ static int efx_enqueue_skb_pio(struct efx_tx_queue *tx_queue,
}
#endif /* EFX_USE_PIO */

+/* Send any pending traffic for a channel. xmit_more is shared across all
+ * queues for a channel, so we must check all of them.
+ */
+static void efx_tx_send_pending(struct efx_channel *channel)
+{
+ struct efx_tx_queue *q;
+
+ efx_for_each_channel_tx_queue(q, channel) {
+ if (q->xmit_pending)
+ efx_nic_push_buffers(q);
+ }
+}
+
/*
* Add a socket buffer to a TX queue
*
@@ -336,21 +349,11 @@ netdev_tx_t __efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb

efx_tx_maybe_stop_queue(tx_queue);

- /* Pass off to hardware */
- if (__netdev_tx_sent_queue(tx_queue->core_txq, skb_len, xmit_more)) {
- struct efx_tx_queue *txq2 = efx_tx_queue_partner(tx_queue);
-
- /* There could be packets left on the partner queue if
- * xmit_more was set. If we do not push those they
- * could be left for a long time and cause a netdev watchdog.
- */
- if (txq2->xmit_more_available)
- efx_nic_push_buffers(txq2);
+ tx_queue->xmit_pending = true;

- efx_nic_push_buffers(tx_queue);
- } else {
- tx_queue->xmit_more_available = xmit_more;
- }
+ /* Pass off to hardware */
+ if (__netdev_tx_sent_queue(tx_queue->core_txq, skb_len, xmit_more))
+ efx_tx_send_pending(tx_queue->channel);

if (segments) {
tx_queue->tso_bursts++;
@@ -371,14 +374,8 @@ netdev_tx_t __efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb
* on this queue or a partner queue then we need to push here to get the
* previous packets out.
*/
- if (!xmit_more) {
- struct efx_tx_queue *txq2 = efx_tx_queue_partner(tx_queue);
-
- if (txq2->xmit_more_available)
- efx_nic_push_buffers(txq2);
-
- efx_nic_push_buffers(tx_queue);
- }
+ if (!xmit_more)
+ efx_tx_send_pending(tx_queue->channel);

return NETDEV_TX_OK;
}
@@ -489,18 +486,24 @@ netdev_tx_t efx_hard_start_xmit(struct sk_buff *skb,

EFX_WARN_ON_PARANOID(!netif_device_present(net_dev));

- /* PTP "event" packet */
- if (unlikely(efx_xmit_with_hwtstamp(skb)) &&
- unlikely(efx_ptp_is_ptp_tx(efx, skb))) {
- return efx_ptp_tx(efx, skb);
- }
-
index = skb_get_queue_mapping(skb);
type = skb->ip_summed == CHECKSUM_PARTIAL ? EFX_TXQ_TYPE_OFFLOAD : 0;
if (index >= efx->n_tx_channels) {
index -= efx->n_tx_channels;
type |= EFX_TXQ_TYPE_HIGHPRI;
}
+
+ /* PTP "event" packet */
+ if (unlikely(efx_xmit_with_hwtstamp(skb)) &&
+ unlikely(efx_ptp_is_ptp_tx(efx, skb))) {
+ /* There may be existing transmits on the channel that are
+ * waiting for this packet to trigger the doorbell write.
+ * We need to send the packets at this point.
+ */
+ efx_tx_send_pending(efx_get_tx_channel(efx, index));
+ return efx_ptp_tx(efx, skb);
+ }
+
tx_queue = efx_get_tx_queue(efx, index, type);

return __efx_enqueue_skb(tx_queue, skb);
diff --git a/drivers/net/ethernet/sfc/tx_common.c b/drivers/net/ethernet/sfc/tx_common.c
index 793e234819a8c..187d5c379a377 100644
--- a/drivers/net/ethernet/sfc/tx_common.c
+++ b/drivers/net/ethernet/sfc/tx_common.c
@@ -78,7 +78,7 @@ void efx_init_tx_queue(struct efx_tx_queue *tx_queue)
tx_queue->read_count = 0;
tx_queue->old_read_count = 0;
tx_queue->empty_read_count = 0 | EFX_EMPTY_COUNT_VALID;
- tx_queue->xmit_more_available = false;
+ tx_queue->xmit_pending = false;
tx_queue->timestamping = (efx_ptp_use_mac_tx_timestamps(efx) &&
tx_queue->channel == efx_ptp_channel(efx));
tx_queue->completed_timestamp_major = 0;
@@ -116,7 +116,7 @@ void efx_fini_tx_queue(struct efx_tx_queue *tx_queue)

++tx_queue->read_count;
}
- tx_queue->xmit_more_available = false;
+ tx_queue->xmit_pending = false;
netdev_tx_reset_queue(tx_queue->core_txq);
}

--
2.25.1