From 8adaf0da869a17ba37ab7d5cf4fddbf5d878978f Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Wed, 21 Feb 2024 21:08:12 +0100
Subject: kernel: integrate the proc_ns_next fixes into proc_next

---
 src/kernel/proc.c | 49 ++++++++++++++++++++++---------------------------
 1 file changed, 22 insertions(+), 27 deletions(-)

(limited to 'src/kernel/proc.c')

diff --git a/src/kernel/proc.c b/src/kernel/proc.c
index dc17af2..26b9e3a 100644
--- a/src/kernel/proc.c
+++ b/src/kernel/proc.c
@@ -145,34 +145,26 @@ Proc *proc_ns_byid(Proc *ns, uint32_t id) {
 	return NULL;
 }
 
+/** Used for iterating over all processes in ns. */
 Proc *proc_ns_next(Proc *ns, Proc *p) {
-	Proc *ret = NULL;
-	/* see comments in proc_next */
+	/* analogous to proc_next */
+	assert(ns);
+	assert(ns->pns == ns); /* is ns the namespace root? */
+	assert(p);
+	assert(proc_ns_contains(ns, p));
 
-	if (!p) goto end;
-	/* descend into children who own their own namespace, but no further */
 	if (p->child && proc_ns_contains(ns, p->child)) {
-		ret = p->child;
-		goto end;
-	}
-	// TODO diverged from proc_next, integrate this fix into it
-	// also once you do that do regression tests - this behaviour is buggy
-	if (p == ns) {
-		/* don't escape the root */
-		goto end;
+		return p->child;
 	}
+
 	while (!p->sibling) {
+		if (p == ns) return NULL;
 		p = p->parent;
 		assert(p);
-		if (p == ns) goto end;
-	}
-	ret = p->sibling;
-
-end:
-	if (ret != NULL) {
-		assert(proc_ns_contains(ns, ret));
+		assert(proc_ns_contains(ns, p));
 	}
-	return ret;
+	if (p == ns) return NULL;
+	return p->sibling;
 }
 
 void proc_ns_create(Proc *proc) {
@@ -447,7 +439,7 @@ _Noreturn void proc_switch_any(void) {
 		if (proc_cur && proc_cur->state == PS_RUNNING) {
 			p = proc_cur;
 		} else {
-			for (p = proc_first; p; p = proc_next(p, NULL)) {
+			for (p = proc_first; p; p = proc_next(proc_first, p)) {
 				if (p->state == PS_RUNNING) {
 					break;
 				}
@@ -468,24 +460,27 @@ _Noreturn void proc_switch_any(void) {
 	}
 }
 
-Proc *proc_next(Proc *p, Proc *root) {
-	/* depth-first search, the order is:
+/** Used for iterating over all descendants of root. */
+Proc *proc_next(Proc *root, Proc *p) {
+	/* depth-first traversal, in this order:
 	 *         1
 	 *        / \
 	 *       2   5
 	 *      /|   |\
 	 *     3 4   6 7
 	 */
-	if (!p) return NULL;
+	assert(root);
+	assert(p);
+
 	if (p->child) return p->child;
-	if (p->sibling) return p->sibling;
 
 	/* looking at the diagram above - we're at 4, want to find 5 */
 	while (!p->sibling) {
+		if (p == root) return NULL;
 		p = p->parent;
-		if (root) assert(p);
-		if (!p || p == root) return NULL;
+		assert(p);
 	}
+	if (p == root) return NULL;
 	return p->sibling;
 }
 
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