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Commit ffd042f1 authored by Sharath Chandra Vurukala's avatar Sharath Chandra Vurukala Committed by Gerrit - the friendly Code Review server
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dfc: reset tx queue 



When a bearer is removed, calling qdisc reset on a tx queue
could have a race condition with qdisc dequeue for lockless
qdisc such as pfifo_fast.

This change uses a different mechanism not relying on qdisc
implementation to achieve packet purge on bearer remove.

Change-Id: I8f9201809853b07293896d6cb8e010e9e0904e46
Signed-off-by: default avatarWeiyi Chen <quic_weiyic@quicinc.com>
Signed-off-by: default avatarSharath Chandra Vurukala <quic_sharathv@quicinc.com>
parent b6a0597c

drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c

+10 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/* Copyright (c) 2013-2020, The Linux Foundation. All rights reserved.

 * Copyright (c) 2021-2022, Qualcomm Innovation Center, Inc. All rights reserved.

 *

 * RMNET Data virtual network driver

 *
@@ -57,6 +58,7 @@ static netdev_tx_t rmnet_vnd_start_xmit(struct sk_buff *skb, 
	int ip_type;

	u32 mark;

	unsigned int len;

	bool need_to_drop = false;



	priv = netdev_priv(dev);

	if (priv->real_dev) {
@@ -65,6 +67,14 @@ static netdev_tx_t rmnet_vnd_start_xmit(struct sk_buff *skb, 
		mark = skb->mark;

		len = skb->len;

		trace_rmnet_xmit_skb(skb);



		qmi_rmnet_get_flow_state(dev, skb, &need_to_drop);

		if (unlikely(need_to_drop)) {

			this_cpu_inc(priv->pcpu_stats->stats.tx_drops);

			kfree_skb(skb);

			return NETDEV_TX_OK;

		}



		rmnet_egress_handler(skb);

		qmi_rmnet_burst_fc_check(dev, ip_type, mark, len);

		qmi_rmnet_work_maybe_restart(rmnet_get_rmnet_port(dev));

drivers/soc/qcom/qmi_rmnet.c

+37 −25
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/*

 * Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.

 * Copyright (c) 2021 Qualcomm Innovation Center, Inc. All rights reserved.

 * Copyright (c) 2021-2022, Qualcomm Innovation Center, Inc. All rights reserved.

 */



#include <soc/qcom/qmi_rmnet.h>
@@ -214,21 +214,6 @@ int qmi_rmnet_flow_control(struct net_device *dev, u32 mq_idx, int enable) 
	return 0;

}



static void qmi_rmnet_reset_txq(struct net_device *dev, unsigned int txq)

{

	struct Qdisc *qdisc;



	if (unlikely(txq >= dev->num_tx_queues))

		return;



	qdisc = rtnl_dereference(netdev_get_tx_queue(dev, txq)->qdisc);

	if (qdisc) {

		spin_lock_bh(qdisc_lock(qdisc));

		qdisc_reset(qdisc);

		spin_unlock_bh(qdisc_lock(qdisc));

	}

}



/**

 * qmi_rmnet_watchdog_fn - watchdog timer func

 */
@@ -354,17 +339,18 @@ static void __qmi_rmnet_bearer_put(struct net_device *dev, 
				continue;



			mq->bearer = NULL;

			if (reset) {

				qmi_rmnet_reset_txq(dev, i);

				qmi_rmnet_flow_control(dev, i, 1);

			mq->drop_on_remove = reset;

			/* Let other CPU's see this update so that packets are

			 * dropped, instead of further processing packets

			 */

			smp_mb();



			qmi_rmnet_flow_control(dev, i, 1);

			if (dfc_mode == DFC_MODE_SA) {

				j = i + ACK_MQ_OFFSET;

					qmi_rmnet_reset_txq(dev, j);

				qmi_rmnet_flow_control(dev, j, 1);

			}

		}

		}



		/* Remove from bearer map */

		list_del(&bearer->list);
@@ -386,6 +372,11 @@ static void __qmi_rmnet_update_mq(struct net_device *dev, 
	mq = &qos_info->mq[itm->mq_idx];

	if (!mq->bearer) {

		mq->bearer = bearer;

		mq->drop_on_remove = false;

		/* Let other CPU's see this update so that packets are

		 * dropped, instead of further processing packets

		 */

		smp_mb();



		if (dfc_mode == DFC_MODE_SA) {

			bearer->mq_idx = itm->mq_idx;
@@ -862,6 +853,27 @@ bool qmi_rmnet_all_flows_enabled(struct net_device *dev) 
EXPORT_SYMBOL(qmi_rmnet_all_flows_enabled);



#ifdef CONFIG_QCOM_QMI_DFC

bool qmi_rmnet_get_flow_state(struct net_device *dev, struct sk_buff *skb,

			      bool *drop)

{

	struct qos_info *qos = rmnet_get_qos_pt(dev);

	int txq = skb->queue_mapping;



	if (txq > ACK_MQ_OFFSET)

		txq -= ACK_MQ_OFFSET;



	if (unlikely(!qos || txq >= MAX_MQ_NUM))

		return false;



	/* If the bearer is gone, packets may need to be dropped */

	*drop = (txq != DEFAULT_MQ_NUM && !READ_ONCE(qos->mq[txq].bearer) &&

		 READ_ONCE(qos->mq[txq].drop_on_remove));



	return true;

}

EXPORT_SYMBOL(qmi_rmnet_get_flow_state);





void qmi_rmnet_burst_fc_check(struct net_device *dev,

			      int ip_type, u32 mark, unsigned int len)

{

drivers/soc/qcom/qmi_rmnet_i.h

+2 −1
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/*

 * Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.

 * Copyright (c) 2021 Qualcomm Innovation Center, Inc. All rights reserved.

 * Copyright (c) 2021-2022, Qualcomm Innovation Center, Inc. All rights reserved.

 */



#ifndef _RMNET_QMI_I_H
@@ -73,6 +73,7 @@ struct svc_info { 


struct mq_map {

	struct rmnet_bearer_map *bearer;

	bool drop_on_remove;

};



struct qos_info {

include/soc/qcom/qmi_rmnet.h

+10 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/*

 * Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.

 * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.

 */



#ifndef _QMI_RMNET_H
@@ -48,6 +49,8 @@ void *qmi_rmnet_qos_init(struct net_device *real_dev, 
			 struct net_device *vnd_dev, u8 mux_id);

void qmi_rmnet_qos_exit_pre(void *qos);

void qmi_rmnet_qos_exit_post(void);

bool qmi_rmnet_get_flow_state(struct net_device *dev, struct sk_buff *skb,

			      bool *drop);

void qmi_rmnet_burst_fc_check(struct net_device *dev,

			      int ip_type, u32 mark, unsigned int len);

int qmi_rmnet_get_queue(struct net_device *dev, struct sk_buff *skb);
@@ -67,6 +70,13 @@ static inline void qmi_rmnet_qos_exit_post(void) 
{

}



static inline bool qmi_rmnet_get_flow_state(struct net_device *dev,

					    struct sk_buff *skb,

					    bool *drop)

{

	return false;

}



static inline void

qmi_rmnet_burst_fc_check(struct net_device *dev,

			 int ip_type, u32 mark, unsigned int len)