6 files changed, 126 insertions, 91 deletions

diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index ff649ebef637..bc6d21b471be 100644
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c
@@ -1604,6 +1604,22 @@ efx_ef10_mcdi_read_response(struct efx_nic *efx, efx_dword_t *outbuf,
 	memcpy(outbuf, pdu + offset, outlen);
 }
 
+static void efx_ef10_mcdi_reboot_detected(struct efx_nic *efx)
+{
+	struct efx_ef10_nic_data *nic_data = efx->nic_data;
+
+	/* All our allocations have been reset */
+	efx_ef10_reset_mc_allocations(efx);
+
+	/* The datapath firmware might have been changed */
+	nic_data->must_check_datapath_caps = true;
+
+	/* MAC statistics have been cleared on the NIC; clear the local
+	 * statistic that we update with efx_update_diff_stat().
+	 */
+	nic_data->stats[EF10_STAT_port_rx_bad_bytes] = 0;
+}
+
 static int efx_ef10_mcdi_poll_reboot(struct efx_nic *efx)
 {
 	struct efx_ef10_nic_data *nic_data = efx->nic_data;
@@ -1623,17 +1639,7 @@ static int efx_ef10_mcdi_poll_reboot(struct efx_nic *efx)
 		return 0;
 
 	nic_data->warm_boot_count = rc;
-
-	/* All our allocations have been reset */
-	efx_ef10_reset_mc_allocations(efx);
-
-	/* The datapath firmware might have been changed */
-	nic_data->must_check_datapath_caps = true;
-
-	/* MAC statistics have been cleared on the NIC; clear the local
-	 * statistic that we update with efx_update_diff_stat().
-	 */
-	nic_data->stats[EF10_STAT_port_rx_bad_bytes] = 0;
+	efx_ef10_mcdi_reboot_detected(efx);
 
 	return -EIO;
 }
@@ -1849,7 +1855,9 @@ static void efx_ef10_tx_write(struct efx_tx_queue *tx_queue)
 	unsigned int write_ptr;
 	efx_qword_t *txd;
 
-	BUG_ON(tx_queue->write_count == tx_queue->insert_count);
+	tx_queue->xmit_more_available = false;
+	if (unlikely(tx_queue->write_count == tx_queue->insert_count))
+		return;
 
 	do {
 		write_ptr = tx_queue->write_count & tx_queue->ptr_mask;
@@ -4670,6 +4678,7 @@ const struct efx_nic_type efx_hunt_a0_vf_nic_type = {
 	.mcdi_poll_response = efx_ef10_mcdi_poll_response,
 	.mcdi_read_response = efx_ef10_mcdi_read_response,
 	.mcdi_poll_reboot = efx_ef10_mcdi_poll_reboot,
+	.mcdi_reboot_detected = efx_ef10_mcdi_reboot_detected,
 	.irq_enable_master = efx_port_dummy_op_void,
 	.irq_test_generate = efx_ef10_irq_test_generate,
 	.irq_disable_non_ev = efx_port_dummy_op_void,
@@ -4774,6 +4783,7 @@ const struct efx_nic_type efx_hunt_a0_nic_type = {
 	.mcdi_poll_response = efx_ef10_mcdi_poll_response,
 	.mcdi_read_response = efx_ef10_mcdi_read_response,
 	.mcdi_poll_reboot = efx_ef10_mcdi_poll_reboot,
+	.mcdi_reboot_detected = efx_ef10_mcdi_reboot_detected,
 	.irq_enable_master = efx_port_dummy_op_void,
 	.irq_test_generate = efx_ef10_irq_test_generate,
 	.irq_disable_non_ev = efx_port_dummy_op_void,
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 974637d3ae25..6e11ee6173ce 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -2062,7 +2062,7 @@ static void efx_init_napi_channel(struct efx_channel *channel)
 	netif_napi_add(channel->napi_dev, &channel->napi_str,
 		       efx_poll, napi_weight);
 	napi_hash_add(&channel->napi_str);
-	efx_channel_init_lock(channel);
+	efx_channel_busy_poll_init(channel);
 }
 
 static void efx_init_napi(struct efx_nic *efx)
@@ -2125,7 +2125,7 @@ static int efx_busy_poll(struct napi_struct *napi)
 	if (!netif_running(efx->net_dev))
 		return LL_FLUSH_FAILED;
 
-	if (!efx_channel_lock_poll(channel))
+	if (!efx_channel_try_lock_poll(channel))
 		return LL_FLUSH_BUSY;
 
 	old_rx_packets = channel->rx_queue.rx_packets;
diff --git a/drivers/net/ethernet/sfc/farch.c b/drivers/net/ethernet/sfc/farch.c
index f08266f0eca2..5a1c5a8f278a 100644
--- a/drivers/net/ethernet/sfc/farch.c
+++ b/drivers/net/ethernet/sfc/farch.c
@@ -321,7 +321,9 @@ void efx_farch_tx_write(struct efx_tx_queue *tx_queue)
 	unsigned write_ptr;
 	unsigned old_write_count = tx_queue->write_count;
 
-	BUG_ON(tx_queue->write_count == tx_queue->insert_count);
+	tx_queue->xmit_more_available = false;
+	if (unlikely(tx_queue->write_count == tx_queue->insert_count))
+		return;
 
 	do {
 		write_ptr = tx_queue->write_count & tx_queue->ptr_mask;
diff --git a/drivers/net/ethernet/sfc/mcdi.c b/drivers/net/ethernet/sfc/mcdi.c
index a9b9460de0d6..41fb6b60a3f0 100644
--- a/drivers/net/ethernet/sfc/mcdi.c
+++ b/drivers/net/ethernet/sfc/mcdi.c
@@ -1028,10 +1028,21 @@ static void efx_mcdi_ev_death(struct efx_nic *efx, int rc)
 
 		/* Consume the status word since efx_mcdi_rpc_finish() won't */
 		for (count = 0; count < MCDI_STATUS_DELAY_COUNT; ++count) {
-			if (efx_mcdi_poll_reboot(efx))
+			rc = efx_mcdi_poll_reboot(efx);
+			if (rc)
 				break;
 			udelay(MCDI_STATUS_DELAY_US);
 		}
+
+		/* On EF10, a CODE_MC_REBOOT event can be received without the
+		 * reboot detection in efx_mcdi_poll_reboot() being triggered.
+		 * If zero was returned from the final call to
+		 * efx_mcdi_poll_reboot(), the MC reboot wasn't noticed but the
+		 * MC has definitely rebooted so prepare for the reset.
+		 */
+		if (!rc && efx->type->mcdi_reboot_detected)
+			efx->type->mcdi_reboot_detected(efx);
+
 		mcdi->new_epoch = true;
 
 		/* Nobody was waiting for an MCDI request, so trigger a reset */
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index c530e1c4cb4f..a8ddd122f685 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -219,6 +219,7 @@ struct efx_tx_buffer {
  * @tso_packets: Number of packets via the TSO xmit path
  * @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
  * @empty_read_count: If the completion path has seen the queue as empty
  *	and the transmission path has not yet checked this, the value of
  *	@read_count bitwise-added to %EFX_EMPTY_COUNT_VALID; otherwise 0.
@@ -253,6 +254,7 @@ struct efx_tx_queue {
 	unsigned int tso_packets;
 	unsigned int pushes;
 	unsigned int pio_packets;
+	bool xmit_more_available;
 	/* Statistics to supplement MAC stats */
 	unsigned long tx_packets;
 
@@ -431,21 +433,8 @@ struct efx_channel {
 	struct net_device *napi_dev;
 	struct napi_struct napi_str;
 #ifdef CONFIG_NET_RX_BUSY_POLL
-	unsigned int state;
-	spinlock_t state_lock;
-#define EFX_CHANNEL_STATE_IDLE		0
-#define EFX_CHANNEL_STATE_NAPI		(1 << 0)  /* NAPI owns this channel */
-#define EFX_CHANNEL_STATE_POLL		(1 << 1)  /* poll owns this channel */
-#define EFX_CHANNEL_STATE_DISABLED	(1 << 2)  /* channel is disabled */
-#define EFX_CHANNEL_STATE_NAPI_YIELD	(1 << 3)  /* NAPI yielded this channel */
-#define EFX_CHANNEL_STATE_POLL_YIELD	(1 << 4)  /* poll yielded this channel */
-#define EFX_CHANNEL_OWNED \
-	(EFX_CHANNEL_STATE_NAPI | EFX_CHANNEL_STATE_POLL)
-#define EFX_CHANNEL_LOCKED \
-	(EFX_CHANNEL_OWNED | EFX_CHANNEL_STATE_DISABLED)
-#define EFX_CHANNEL_USER_PEND \
-	(EFX_CHANNEL_STATE_POLL | EFX_CHANNEL_STATE_POLL_YIELD)
-#endif /* CONFIG_NET_RX_BUSY_POLL */
+	unsigned long busy_poll_state;
+#endif
 	struct efx_special_buffer eventq;
 	unsigned int eventq_mask;
 	unsigned int eventq_read_ptr;
@@ -480,98 +469,94 @@ struct efx_channel {
 };
 
 #ifdef CONFIG_NET_RX_BUSY_POLL
-static inline void efx_channel_init_lock(struct efx_channel *channel)
+enum efx_channel_busy_poll_state {
+	EFX_CHANNEL_STATE_IDLE = 0,
+	EFX_CHANNEL_STATE_NAPI = BIT(0),
+	EFX_CHANNEL_STATE_NAPI_REQ_BIT = 1,
+	EFX_CHANNEL_STATE_NAPI_REQ = BIT(1),
+	EFX_CHANNEL_STATE_POLL_BIT = 2,
+	EFX_CHANNEL_STATE_POLL = BIT(2),
+	EFX_CHANNEL_STATE_DISABLE_BIT = 3,
+};
+
+static inline void efx_channel_busy_poll_init(struct efx_channel *channel)
 {
-	spin_lock_init(&channel->state_lock);
+	WRITE_ONCE(channel->busy_poll_state, EFX_CHANNEL_STATE_IDLE);
 }
 
 /* Called from the device poll routine to get ownership of a channel. */
 static inline bool efx_channel_lock_napi(struct efx_channel *channel)
 {
-	bool rc = true;
-
-	spin_lock_bh(&channel->state_lock);
-	if (channel->state & EFX_CHANNEL_LOCKED) {
-		WARN_ON(channel->state & EFX_CHANNEL_STATE_NAPI);
-		channel->state |= EFX_CHANNEL_STATE_NAPI_YIELD;
-		rc = false;
-	} else {
-		/* we don't care if someone yielded */
-		channel->state = EFX_CHANNEL_STATE_NAPI;
+	unsigned long prev, old = READ_ONCE(channel->busy_poll_state);
+
+	while (1) {
+		switch (old) {
+		case EFX_CHANNEL_STATE_POLL:
+			/* Ensure efx_channel_try_lock_poll() wont starve us */
+			set_bit(EFX_CHANNEL_STATE_NAPI_REQ_BIT,
+				&channel->busy_poll_state);
+			/* fallthrough */
+		case EFX_CHANNEL_STATE_POLL | EFX_CHANNEL_STATE_NAPI_REQ:
+			return false;
+		default:
+			break;
+		}
+		prev = cmpxchg(&channel->busy_poll_state, old,
+			       EFX_CHANNEL_STATE_NAPI);
+		if (unlikely(prev != old)) {
+			/* This is likely to mean we've just entered polling
+			 * state. Go back round to set the REQ bit.
+			 */
+			old = prev;
+			continue;
+		}
+		return true;
 	}
-	spin_unlock_bh(&channel->state_lock);
-	return rc;
 }
 
 static inline void efx_channel_unlock_napi(struct efx_channel *channel)
 {
-	spin_lock_bh(&channel->state_lock);
-	WARN_ON(channel->state &
-		(EFX_CHANNEL_STATE_POLL | EFX_CHANNEL_STATE_NAPI_YIELD));
-
-	channel->state &= EFX_CHANNEL_STATE_DISABLED;
-	spin_unlock_bh(&channel->state_lock);
+	/* Make sure write has completed from efx_channel_lock_napi() */
+	smp_wmb();
+	WRITE_ONCE(channel->busy_poll_state, EFX_CHANNEL_STATE_IDLE);
 }
 
 /* Called from efx_busy_poll(). */
-static inline bool efx_channel_lock_poll(struct efx_channel *channel)
+static inline bool efx_channel_try_lock_poll(struct efx_channel *channel)
 {
-	bool rc = true;
-
-	spin_lock_bh(&channel->state_lock);
-	if ((channel->state & EFX_CHANNEL_LOCKED)) {
-		channel->state |= EFX_CHANNEL_STATE_POLL_YIELD;
-		rc = false;
-	} else {
-		/* preserve yield marks */
-		channel->state |= EFX_CHANNEL_STATE_POLL;
-	}
-	spin_unlock_bh(&channel->state_lock);
-	return rc;
+	return cmpxchg(&channel->busy_poll_state, EFX_CHANNEL_STATE_IDLE,
+			EFX_CHANNEL_STATE_POLL) == EFX_CHANNEL_STATE_IDLE;
 }
 
-/* Returns true if NAPI tried to get the channel while it was locked. */
 static inline void efx_channel_unlock_poll(struct efx_channel *channel)
 {
-	spin_lock_bh(&channel->state_lock);
-	WARN_ON(channel->state & EFX_CHANNEL_STATE_NAPI);
-
-	/* will reset state to idle, unless channel is disabled */
-	channel->state &= EFX_CHANNEL_STATE_DISABLED;
-	spin_unlock_bh(&channel->state_lock);
+	clear_bit_unlock(EFX_CHANNEL_STATE_POLL_BIT, &channel->busy_poll_state);
 }
 
-/* True if a socket is polling, even if it did not get the lock. */
 static inline bool efx_channel_busy_polling(struct efx_channel *channel)
 {
-	WARN_ON(!(channel->state & EFX_CHANNEL_OWNED));
-	return channel->state & EFX_CHANNEL_USER_PEND;
+	return test_bit(EFX_CHANNEL_STATE_POLL_BIT, &channel->busy_poll_state);
 }
 
 static inline void efx_channel_enable(struct efx_channel *channel)
 {
-	spin_lock_bh(&channel->state_lock);
-	channel->state = EFX_CHANNEL_STATE_IDLE;
-	spin_unlock_bh(&channel->state_lock);
+	clear_bit_unlock(EFX_CHANNEL_STATE_DISABLE_BIT,
+			 &channel->busy_poll_state);
 }
 
-/* False if the channel is currently owned. */
+/* Stop further polling or napi access.
+ * Returns false if the channel is currently busy polling.
+ */
 static inline bool efx_channel_disable(struct efx_channel *channel)
 {
-	bool rc = true;
-
-	spin_lock_bh(&channel->state_lock);
-	if (channel->state & EFX_CHANNEL_OWNED)
-		rc = false;
-	channel->state |= EFX_CHANNEL_STATE_DISABLED;
-	spin_unlock_bh(&channel->state_lock);
-
-	return rc;
+	set_bit(EFX_CHANNEL_STATE_DISABLE_BIT, &channel->busy_poll_state);
+	/* Implicit barrier in efx_channel_busy_polling() */
+	return !efx_channel_busy_polling(channel);
 }
 
 #else /* CONFIG_NET_RX_BUSY_POLL */
 
-static inline void efx_channel_init_lock(struct efx_channel *channel)
+static inline void efx_channel_busy_poll_init(struct efx_channel *channel)
 {
 }
 
@@ -584,7 +569,7 @@ static inline void efx_channel_unlock_napi(struct efx_channel *channel)
 {
 }
 
-static inline bool efx_channel_lock_poll(struct efx_channel *channel)
+static inline bool efx_channel_try_lock_poll(struct efx_channel *channel)
 {
 	return false;
 }
@@ -1277,6 +1262,7 @@ struct efx_nic_type {
 	void (*mcdi_read_response)(struct efx_nic *efx, efx_dword_t *pdu,
 				   size_t pdu_offset, size_t pdu_len);
 	int (*mcdi_poll_reboot)(struct efx_nic *efx);
+	void (*mcdi_reboot_detected)(struct efx_nic *efx);
 	void (*irq_enable_master)(struct efx_nic *efx);
 	void (*irq_test_generate)(struct efx_nic *efx);
 	void (*irq_disable_non_ev)(struct efx_nic *efx);
diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index 1833a0146571..67f6afaa022f 100644
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -431,8 +431,20 @@ finish_packet:
 	efx_tx_maybe_stop_queue(tx_queue);
 
 	/* Pass off to hardware */
-	if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq))
+	if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq)) {
+		struct efx_tx_queue *txq2 = efx_tx_queue_partner(tx_queue);
+
+		/* There could be packets left on the partner queue if those
+		 * SKBs had skb->xmit_more 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);
+
 		efx_nic_push_buffers(tx_queue);
+	} else {
+		tx_queue->xmit_more_available = skb->xmit_more;
+	}
 
 	tx_queue->tx_packets++;
 
@@ -722,6 +734,7 @@ 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;
 
 	/* Set up TX descriptor ring */
 	efx_nic_init_tx(tx_queue);
@@ -747,6 +760,7 @@ void efx_fini_tx_queue(struct efx_tx_queue *tx_queue)
 
 		++tx_queue->read_count;
 	}
+	tx_queue->xmit_more_available = false;
 	netdev_tx_reset_queue(tx_queue->core_txq);
 }
 
@@ -1302,8 +1316,20 @@ static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
 	efx_tx_maybe_stop_queue(tx_queue);
 
 	/* Pass off to hardware */
-	if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq))
+	if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq)) {
+		struct efx_tx_queue *txq2 = efx_tx_queue_partner(tx_queue);
+
+		/* There could be packets left on the partner queue if those
+		 * SKBs had skb->xmit_more 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);
+
 		efx_nic_push_buffers(tx_queue);
+	} else {
+		tx_queue->xmit_more_available = skb->xmit_more;
+	}
 
 	tx_queue->tso_bursts++;
 	return NETDEV_TX_OK;