caif-shmcore: increase the priority of flow control wq

replace work queue with kthread workqueue for which the priority can be
increased. Priority has to be increased, because ideally there the control
information on flow ctrl i.e ON or OFF should reach caif with no delay.

ST-Ericsson Linux next: NA
ST-Ericsson ID: 372652
ST-Ericsson FOSS-OUT ID: Trivial

Change-Id: I7a148b3277bcc885ade810df12b47c609a631e21
Signed-off-by: Arun Murthy <arun.murthy@stericsson.com>
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/42835
Reviewed-by: Hemant-vilas RAMDASI <hemant.ramdasi@stericsson.com>
Reviewed-by: QABUILD
Reviewed-by: QATEST
Reviewed-by: Sjur BRENDELAND <sjur.brandeland@stericsson.com>
Reviewed-by: Srinidhi KASAGAR <srinidhi.kasagar@stericsson.com>

1 files changed, 22 insertions, 13 deletions

diff --git a/drivers/net/caif/caif_shmcore.c b/drivers/net/caif/caif_shmcore.c
index 7bd35e0c18b..2cdae3fc158 100644
--- a/drivers/net/caif/caif_shmcore.c
+++ b/drivers/net/caif/caif_shmcore.c
@@ -13,6 +13,7 @@
 #include <linux/list.h>
 #include <linux/netdevice.h>
 #include <linux/if_arp.h>
+#include <linux/kthread.h>
 
 #include <net/caif/caif_device.h>
 #include <net/caif/caif_shm.h>
@@ -106,12 +107,14 @@ struct shmdrv_layer {
 
 	struct workqueue_struct *pshm_tx_workqueue;
 	struct workqueue_struct *pshm_rx_workqueue;
-	struct workqueue_struct *pshm_flow_ctrl_workqueue;
+
+	struct kthread_worker pshm_flow_ctrl_kw;
+	struct task_struct *pshm_flow_ctrl_kw_task;
 
 	struct work_struct shm_tx_work;
 	struct work_struct shm_rx_work;
-	struct work_struct shm_flow_on_work;
-	struct work_struct shm_flow_off_work;
+	struct kthread_work shm_flow_on_work;
+	struct kthread_work shm_flow_off_work;
 
 	struct sk_buff_head sk_qhead;
 	struct shmdev_layer *pshm_dev;
@@ -129,7 +132,7 @@ static int shm_netdev_close(struct net_device *shm_netdev)
 	return 0;
 }
 
-static void shm_flow_on_work_func(struct work_struct *work)
+static void shm_flow_on_work_func(struct kthread_work *work)
 {
 	struct shmdrv_layer *pshm_drv = container_of(work, struct shmdrv_layer, shm_flow_on_work);
 
@@ -138,7 +141,7 @@ static void shm_flow_on_work_func(struct work_struct *work)
 			CAIF_FLOW_ON);
 }
 
-static void shm_flow_off_work_func(struct work_struct *work)
+static void shm_flow_off_work_func(struct kthread_work *work)
 {
 	struct shmdrv_layer *pshm_drv = container_of(work, struct shmdrv_layer, shm_flow_off_work);
 
@@ -259,7 +262,7 @@ int caif_shmdrv_rx_cb(u32 mbx_msg, void *priv)
 		if ((avail_emptybuff > HIGH_WATERMARK) &&
 					(!pshm_drv->tx_empty_available)) {
 			pshm_drv->tx_empty_available = 1;
-			queue_work(pshm_drv->pshm_flow_ctrl_workqueue,
+			queue_kthread_work(&pshm_drv->pshm_flow_ctrl_kw,
 					&pshm_drv->shm_flow_on_work);
 			spin_unlock_irqrestore(&pshm_drv->lock, flags);
 
@@ -445,7 +448,7 @@ static void shm_tx_work_func(struct work_struct *tx_work)
 					pshm_drv->tx_empty_available) {
 			/* Update blocking condition. */
 			pshm_drv->tx_empty_available = 0;
-			queue_work(pshm_drv->pshm_flow_ctrl_workqueue,
+			queue_kthread_work(&pshm_drv->pshm_flow_ctrl_kw,
 					&pshm_drv->shm_flow_off_work);
 		}
 		/*
@@ -578,6 +581,7 @@ int caif_shmcore_probe(struct shmdev_layer *pshm_dev)
 {
 	int result, j;
 	struct shmdrv_layer *pshm_drv = NULL;
+	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
 
 	pshm_dev->pshm_netdev = alloc_netdev(sizeof(struct shmdrv_layer),
 						"cfshm%d", shm_netdev_setup);
@@ -637,16 +641,20 @@ int caif_shmcore_probe(struct shmdev_layer *pshm_dev)
 
 	INIT_WORK(&pshm_drv->shm_tx_work, shm_tx_work_func);
 	INIT_WORK(&pshm_drv->shm_rx_work, shm_rx_work_func);
-	INIT_WORK(&pshm_drv->shm_flow_on_work, shm_flow_on_work_func);
-	INIT_WORK(&pshm_drv->shm_flow_off_work, shm_flow_off_work_func);
+
+	init_kthread_work(&pshm_drv->shm_flow_on_work, shm_flow_on_work_func);
+	init_kthread_work(&pshm_drv->shm_flow_off_work, shm_flow_off_work_func);
 
 	pshm_drv->pshm_tx_workqueue =
 				create_singlethread_workqueue("shm_tx_work");
 	pshm_drv->pshm_rx_workqueue =
 				create_singlethread_workqueue("shm_rx_work");
-	pshm_drv->pshm_flow_ctrl_workqueue =
-				create_singlethread_workqueue(
-						"shm_caif_flow_ctrl_work");
+
+	init_kthread_worker(&pshm_drv->pshm_flow_ctrl_kw);
+	pshm_drv->pshm_flow_ctrl_kw_task = kthread_run(kthread_worker_fn,
+			&pshm_drv->pshm_flow_ctrl_kw, "pshm_caif_flow_ctrl");
+	/* must use the FIFO scheduler as it is realtime sensitive */
+	sched_setscheduler(pshm_drv->pshm_flow_ctrl_kw_task, SCHED_FIFO, &param);
 
 	for (j = 0; j < NR_TX_BUF; j++) {
 		struct buf_list *tx_buf =
@@ -765,7 +773,8 @@ void caif_shmcore_remove(struct net_device *pshm_netdev)
 	/* Destroy work queues. */
 	destroy_workqueue(pshm_drv->pshm_tx_workqueue);
 	destroy_workqueue(pshm_drv->pshm_rx_workqueue);
-	destroy_workqueue(pshm_drv->pshm_flow_ctrl_workqueue);
+	flush_kthread_worker(&pshm_drv->pshm_flow_ctrl_kw);
+	kthread_stop(pshm_drv->pshm_flow_ctrl_kw_task);
 
 	unregister_netdev(pshm_netdev);
 }