[SQUASH] Drop threaded NAPI

This reverts the following commits
89ce123 qcacld-3.0: Enable threaded NAPI
ad53cf0 msm: ipa3: Enable threaded NAPI
59918fb net: fix hangup on napi_disable for threaded napi
158caad net: fix race between napi kthread mode and busy poll
2a51a72 net: add sysfs attribute to control napi threaded mode
2a39a03 net: implement threaded-able napi poll loop support
dd75fc8 net: extract napi poll functionality to __napi_poll()

* Causes kernel panics at very random times, and for a very minimal/non-existent performance improvement

Signed-off-by: Yahya Wessam <yahyawessam2002@gmail.com>

Author: vbajs

Documentation/ABI/testing/sysfs-class-net

@@ -259,18 +259,3 @@ Contact:	netdev@vger.kernel.org
 Description:
 		Symbolic link to the PHY device this network device is attached
 		to.
-
-		What:		/sys/class/net/<iface>/threaded
-		Date:		Jan 2021
-		KernelVersion:	5.12
-		Contact:	netdev@vger.kernel.org
-		Description:
-				Boolean value to control the threaded mode per device. User could
-				set this value to enable/disable threaded mode for all napi
-				belonging to this device, without the need to do device up/down.
-		
-				Possible values:
-				== ==================================
-				0  threaded mode disabled for this dev
-				1  threaded mode enabled for this dev
-				== ==================================

drivers/platform/msm/ipa/ipa_v3/rmnet_ipa.c

@@ -1141,10 +1141,8 @@ static int __ipa_wwan_open(struct net_device *dev)
 		reinit_completion(&wwan_ptr->resource_granted_completion);
 	wwan_ptr->device_status = WWAN_DEVICE_ACTIVE;
 
-	if (ipa3_rmnet_res.ipa_napi_enable) {
-		dev_set_threaded(dev, true);
+	if (ipa3_rmnet_res.ipa_napi_enable)
 		napi_enable(&(wwan_ptr->napi));
-	}
 	return 0;
 }
 

drivers/staging/qca-wifi-host-cmn/hif/src/hif_exec.c

@@ -698,7 +698,6 @@ static struct hif_exec_context *hif_exec_napi_create(uint32_t scale)
 	qdf_net_if_create_dummy_if((struct qdf_net_if *)&ctx->netdev);
 	netif_napi_add(&(ctx->netdev), &(ctx->napi), hif_exec_poll,
 		       QCA_NAPI_BUDGET);
-	dev_set_threaded(&(ctx->netdev), true);
 	napi_enable(&ctx->napi);
 
 	return &ctx->exec_ctx;

drivers/staging/qca-wifi-host-cmn/hif/src/hif_napi.c

@@ -82,7 +82,6 @@ static void hif_init_rx_thread_napi(struct qca_napi_info *napii)
 	init_dummy_netdev(&napii->rx_thread_netdev);
 	netif_napi_add(&napii->rx_thread_netdev, &napii->rx_thread_napi,
 		       hif_rxthread_napi_poll, 64);
-	dev_set_threaded(&napii->rx_thread_netdev, true);
 	napi_enable(&napii->rx_thread_napi);
 }
 
@@ -683,7 +682,6 @@ int hif_napi_event(struct hif_opaque_softc *hif_ctx, enum qca_napi_event event,
 					napi = &(napii->napi);
 					NAPI_DEBUG("%s: enabling NAPI %d",
 						   __func__, i);
-					dev_set_threaded(napi->dev, true);
 					napi_enable(napi);
 				}
 			}
@@ -695,7 +693,6 @@ int hif_napi_event(struct hif_opaque_softc *hif_ctx, enum qca_napi_event event,
 					napi = &(napii->napi);
 					NAPI_DEBUG("%s: disabling NAPI %d",
 						   __func__, i);
-					dev_set_threaded(napi->dev, false);
 					napi_disable(napi);
 					/* in case it is affined, remove it */
 					qdf_dev_set_irq_affinity(napii->irq,

drivers/staging/qcacld-3.0/core/dp/txrx3.0/dp_rx_thread.c

@@ -591,7 +591,6 @@ static void dp_rx_tm_thread_napi_init(struct dp_rx_thread *rx_thread)
 	init_dummy_netdev(&rx_thread->netdev);
 	netif_napi_add(&rx_thread->netdev, &rx_thread->napi,
 		       dp_rx_tm_thread_napi_poll, 64);
-	dev_set_threaded(&rx_thread->netdev, true);
 	napi_enable(&rx_thread->napi);
 }
 

include/linux/netdevice.h

@@ -338,7 +338,6 @@ struct napi_struct {
 	struct list_head	dev_list;
 	struct hlist_node	napi_hash_node;
 	unsigned int		napi_id;
-	struct task_struct	*thread;
 };
 
 enum {
@@ -349,8 +348,6 @@ enum {
 	NAPI_STATE_HASHED,	/* In NAPI hash (busy polling possible) */
 	NAPI_STATE_NO_BUSY_POLL,/* Do not add in napi_hash, no busy polling */
 	NAPI_STATE_IN_BUSY_POLL,/* sk_busy_loop() owns this NAPI */
-	NAPI_STATE_THREADED,	/* The poll is performed inside its own thread*/
-	NAPI_STATE_SCHED_THREADED,/* Napi is currently scheduled in threaded mode */
 };
 
 enum {
@@ -361,8 +358,6 @@ enum {
 	NAPIF_STATE_HASHED	 = BIT(NAPI_STATE_HASHED),
 	NAPIF_STATE_NO_BUSY_POLL = BIT(NAPI_STATE_NO_BUSY_POLL),
 	NAPIF_STATE_IN_BUSY_POLL = BIT(NAPI_STATE_IN_BUSY_POLL),
-	NAPIF_STATE_THREADED	 = BIT(NAPI_STATE_THREADED),
-	NAPIF_STATE_SCHED_THREADED	= BIT(NAPI_STATE_SCHED_THREADED),
 };
 
 enum gro_result {
@@ -484,8 +479,6 @@ static inline bool napi_complete(struct napi_struct *n)
 	return napi_complete_done(n, 0);
 }
 
-int dev_set_threaded(struct net_device *dev, bool threaded);
-
 /**
  *	napi_hash_del - remove a NAPI from global table
  *	@napi: NAPI context
@@ -509,7 +502,20 @@ bool napi_hash_del(struct napi_struct *napi);
  */
 void napi_disable(struct napi_struct *n);
 
-void napi_enable(struct napi_struct *n);
+/**
+ *	napi_enable - enable NAPI scheduling
+ *	@n: NAPI context
+ *
+ * Resume NAPI from being scheduled on this context.
+ * Must be paired with napi_disable.
+ */
+static inline void napi_enable(struct napi_struct *n)
+{
+	BUG_ON(!test_bit(NAPI_STATE_SCHED, &n->state));
+	smp_mb__before_atomic();
+	clear_bit(NAPI_STATE_SCHED, &n->state);
+	clear_bit(NAPI_STATE_NPSVC, &n->state);
+}
 
 /**
  *	napi_synchronize - wait until NAPI is not running
@@ -1687,8 +1693,6 @@ enum netdev_priv_flags {
  *			switch driver and used to set the phys state of the
  *			switch port.
  *
- *	@threaded:	napi threaded mode is enabled
- *
  *	@macsec_ops:    MACsec offloading ops
  *
  *	FIXME: cleanup struct net_device such that network protocol info
@@ -1968,7 +1972,6 @@ struct net_device {
 	struct lock_class_key	*qdisc_tx_busylock;
 	struct lock_class_key	*qdisc_running_key;
 	bool			proto_down;
-	unsigned		threaded:1;
 
 #if IS_ENABLED(CONFIG_MACSEC)
 	/* MACsec management functions */