Remove the mechanism for blocking tasks from doing ipc.

Removed previously implemented but untested mechanism of blocking tasks
from doing ipc to certain tasks using certain tags. This is to be considered
for future implementation.

include/l4/generic/tcb.h

@@ -92,10 +92,6 @@ struct ktcb {
 	struct waitqueue_head wqh_recv;
 	struct waitqueue_head wqh_send;
 
-	/* Fields for checking parties blocked from doing ipc */
-	struct spinlock ipc_block_lock;
-	struct list_head ipc_block_list;
-
 	l4id_t senderid;	/* Sender checks this for ipc */
 };
 

src/api/ipc.c

@@ -38,86 +38,9 @@ int ipc_msg_copy(struct ktcb *to, struct ktcb *from)
 	return 0;
 }
 
-/*
- * Means this sender cannot contact this receiver with this type of tag.
- * IOW not accepting a particular type of message from a sender.
- */
-struct ipc_block_data {
-	l4id_t blocked_sender;
-	u32 blocked_tag;
-	struct list_head list;
-};
-
-/*
- * These flags are used on ipc_control call in order to block and unblock a thread
- * from doing ipc with another thread.
- */
-enum ipc_control_flag {
-	IPC_CONTROL_BLOCK = 0,
-	IPC_CONTROL_UNBLOCK
-};
-
-/*
- * This checks if any of the parties are not allowed to talk to each other.
- */
-int ipc_blocked(struct ktcb *receiver, struct ktcb *sender)
-{
-	u32 ipc_tag = *((u32 *)KTCB_REF_MR0(sender));
-	struct ipc_block_data *bdata;
-
-	spin_lock(&receiver->ipc_block_lock);
-	list_for_each_entry(bdata, &receiver->ipc_block_list, list)
-		if (bdata->blocked_sender == sender->tid &&
-		    ipc_tag == bdata->blocked_tag) {
-			spin_unlock(&receiver->ipc_block_lock);
-			return 1;
-		}
-	spin_unlock(&receiver->ipc_block_lock);
-	return 0;
-}
-
-/*
- * Adds and removes task/ipc_tag pairs to/from a task's receive block list.
- * The pairs on this list are prevented to have ipc rendezvous with the task.
- */
 int sys_ipc_control(struct syscall_args *regs)
 {
-	enum ipc_control_flag flag = (enum ipc_control_flag)regs->r0;
-	struct ipc_block_data *bdata;
-	struct ktcb *blocked_sender;
-	l4id_t blocked_tid = (l4id_t)regs->r1;
-	u32 blocked_tag = (u32)regs->r2;
-	int unblocked = 0;
-
-	switch (flag) {
-	case IPC_CONTROL_BLOCK:
-		bdata =	kmalloc(sizeof(struct ipc_block_data));
-		bdata->blocked_sender = blocked_tid;
-		bdata->blocked_tag = blocked_tag;
-		INIT_LIST_HEAD(&bdata->list);
-	       	BUG_ON(!(blocked_sender = find_task(blocked_tid)));
-		BUG_ON(ipc_blocked(current, blocked_sender));
-		spin_lock(&current->ipc_block_lock);
-		list_add(&bdata->list, &current->ipc_block_list);
-		spin_unlock(&current->ipc_block_lock);
-		break;
-	case IPC_CONTROL_UNBLOCK:
-		spin_lock(&current->ipc_block_lock);
-		list_for_each_entry(bdata, &current->ipc_block_list, list)
-			if (bdata->blocked_sender == blocked_tid &&
-			    bdata->blocked_tag == blocked_tag) {
-				unblocked = 1;
-				list_del(&bdata->list);
-				kfree(bdata);
-				break;
-			}
-		spin_unlock(&current->ipc_block_lock);
-		BUG_ON(!unblocked);
-		break;
-	default:
-		printk("%s: Unsupported request.\n", __FUNCTION__);
-	}
-	return 0;
+	return -ENOSYS;
 }
 
 int ipc_send(l4id_t recv_tid)
@@ -129,8 +52,8 @@ int ipc_send(l4id_t recv_tid)
 	spin_lock(&wqhs->slock);
 	spin_lock(&wqhr->slock);
 
-	/* Is my receiver waiting and accepting ipc from me? */
-	if (wqhr->sleepers > 0 && !ipc_blocked(receiver, current)) {
+	/* Is my receiver waiting? */
+	if (wqhr->sleepers > 0) {
 		struct waitqueue *wq, *n;
 		struct ktcb *sleeper;
 
@@ -185,14 +108,9 @@ int ipc_recv(l4id_t senderid)
 
 		list_for_each_entry_safe(wq, n, &wqhs->task_list, task_list) {
 			sleeper = wq->task;
-			/* Found a sender, is it unblocked for rendezvous? */
+			/* Found a sender */
 			if ((sleeper->tid == current->senderid) ||
-			    ((current->senderid == L4_ANYTHREAD) &&
-			     !ipc_blocked(current, sleeper))) {
-				/* Check for bug */
-				BUG_ON(sleeper->tid == current->senderid &&
-				       ipc_blocked(current, sleeper));
-
+			    (current->senderid == L4_ANYTHREAD)) {
 				list_del_init(&wq->task_list);
 				spin_unlock(&wqhr->slock);
 				spin_unlock(&wqhs->slock);

src/glue/arm/init.c

@@ -318,10 +318,6 @@ void init_inittask(char *name, struct task_ids *ids)
 	waitqueue_head_init(&task->wqh_send);
 	waitqueue_head_init(&task->wqh_recv);
 
-	/* Tasks' rendezvous blocked list */
-	spin_lock_init(&task->ipc_block_lock);
-	INIT_LIST_HEAD(&task->ipc_block_list);
-
 	/* Global hashlist that keeps all existing tasks */
 	add_task_global(task);