From 68281c8ad0020f2923dc2361234ecd79948cd118 Mon Sep 17 00:00:00 2001
From: Stefan Lankes <lankes@lfbs.rwth-aachen.de>
Date: Mon, 18 Apr 2011 15:10:24 +0200
Subject: [PATCH] cosmetic changes, minor code optimization

---
 arch/x86/kernel/gdt.c       | 6 +++---
 arch/x86/kernel/irq.c       | 8 +++++---
 arch/x86/kernel/processor.c | 6 +++---
 3 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/gdt.c b/arch/x86/kernel/gdt.c
index b4fd61ae..30e165c7 100644
--- a/arch/x86/kernel/gdt.c
+++ b/arch/x86/kernel/gdt.c
@@ -68,9 +68,6 @@ int arch_fork(task_t* task)
 	memcpy(task_state_segments+id, task_state_segments+curr_task->id, sizeof(tss_t));
 	memcpy(kstacks[id], kstacks[curr_task->id], KERNEL_STACK_SIZE);
 	task_state_segments[id].cr3 = (uint32_t) (virt_to_phys((size_t)task->pgd));
-	task_state_segments[id].eflags = read_eflags();
-	// the parent task will enable the IF flag
-	task_state_segments[id].eflags |= (1 << 9);
 	task_state_segments[id].esp0 = (uint32_t) kstacks[id] + KERNEL_STACK_SIZE - sizeof(size_t);
 
 	asm volatile("mov %%esp, %0" : "=r"(task_state_segments[id].esp));
@@ -91,6 +88,9 @@ int arch_fork(task_t* task)
 	asm volatile ("pop %0" : "=r"(task_state_segments[id].ecx));
 	asm volatile ("pop %0" : "=r"(task_state_segments[id].eax));
 
+	// store current EFLAGS and set IF flag
+	// => the parent task will enable the interrupt handling
+	task_state_segments[id].eflags = read_eflags() | (1 << 9);
 	// This will be the entry point for the new task.
 	task_state_segments[id].eip = read_eip();
 
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 708061dd..3542199f 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -226,9 +226,11 @@ void irq_handler(struct state *s)
 	 * Find out if we have a custom handler to run for this
 	 * IRQ and then finally, run it 
 	 */	
-	handler = irq_routines[s->int_no];
-	if (handler)
-		handler(s);
+	if (BUILTIN_EXPECT(s->int_no < MAX_HANDLERS, 1)) {
+		handler = irq_routines[s->int_no];
+		if (handler)
+			handler(s);
+	} else kprintf("Invalid interrupt number %d\n", s->int_no);
 
 	/* 
 	 * If the IDT entry that was invoked was greater-than-or-equal to 48,
diff --git a/arch/x86/kernel/processor.c b/arch/x86/kernel/processor.c
index 2b1c84bf..aa4988f4 100644
--- a/arch/x86/kernel/processor.c
+++ b/arch/x86/kernel/processor.c
@@ -49,12 +49,12 @@ uint32_t detect_cpu_frequency(void)
 	while((ticks = get_clock_tick()) - old == 0)
 		HALT;
 
-	rmb();
+	mb();
 	start = rdtsc();
 	/* wait a second to determine the frequency */
 	while(get_clock_tick() - ticks < TIMER_FREQ)
 		HALT;
-	rmb();
+	mb();
 	end = rdtsc();
 
 	diff = end > start ? end - start : start - end;
@@ -78,7 +78,7 @@ void udelay(uint32_t usecs)
 	uint64_t deadline = get_cpu_frequency() * usecs;
 
 	do {
-		rmb();
+		mb();
 		end = rdtsc();
 		diff = end > start ? end - start : start - end;
 	} while(diff < deadline);