From 6eb79f812ee43a4e9142de61a5821e0cc8c52bb1 Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Sun, 26 Apr 2015 15:47:47 +0200
Subject: kern: gracefully handle resource shortage

* kern/thread.c (stack_alloc): Report resource shortage.
* kern/sched_prim.h (stack_alloc): Adjust declaration accordingly.
* kern/thread_swap.c (thread_doswapin): Report resource shortage.
(swapin_thread_continue): If the swap-in fails, put the thread back on
the queue and go back to sleep.
* kern/thread_swap.h (thread_doswapin): Adjust declaration accordingly.
---
 kern/thread.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

(limited to 'kern/thread.c')

diff --git a/kern/thread.c b/kern/thread.c
index 009884c..f52c95b 100644
--- a/kern/thread.c
+++ b/kern/thread.c
@@ -171,7 +171,7 @@ boolean_t stack_alloc_try(
  *	May block.
  */
 
-void stack_alloc(
+kern_return_t stack_alloc(
 	thread_t	thread,
 	void		(*resume)(thread_t))
 {
@@ -195,15 +195,15 @@ void stack_alloc(
 	(void) splx(s);
 
 	if (stack == 0) {
+		kern_return_t kr;
 		/*
 		 *	Kernel stacks should be naturally aligned,
 		 *	so that it is easy to find the starting/ending
 		 *	addresses of a stack given an address in the middle.
 		 */
-
-		if (kmem_alloc_aligned(kmem_map, &stack, KERNEL_STACK_SIZE)
-							!= KERN_SUCCESS)
-			panic("stack_alloc");
+		kr = kmem_alloc_aligned(kmem_map, &stack, KERNEL_STACK_SIZE);
+		if (kr != KERN_SUCCESS)
+			return kr;
 
 #if	MACH_DEBUG
 		stack_init(stack);
@@ -211,6 +211,7 @@ void stack_alloc(
 	}
 
 	stack_attach(thread, stack, resume);
+	return KERN_SUCCESS;
 }
 
 /*
-- 
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