Generalize the SpinLock and move it to AK.

Add a separate lock to protect the VFS. I think this might be a good idea.
I'm not sure it's a good approach though. I'll fiddle with it as I go along.

It's really fun to figure out all these things on my own.

Kernel/Syscall.cpp

@@ -2,6 +2,7 @@
 #include "Task.h"
 #include "Syscall.h"
 #include "Console.h"
+#include <AK/Lock.h>
 
 extern "C" void syscall_entry();
 extern "C" void syscall_ISR();
@@ -38,72 +39,6 @@ asm(
     "    iret\n"
 );
 
-static inline dword CAS(dword* mem, dword newval, dword oldval)
-{
-    dword ret;
-    asm volatile(
-        "cmpxchgl %2, %1"
-        :"=a"(ret), "=m"(*mem)
-        :"r"(newval), "m"(*mem), "0"(oldval));
-    return ret;
-}
-
-class SpinLock {
-public:
-    SpinLock()
-    {
-    }
-
-    ~SpinLock()
-    {
-        unlock();
-    }
-
-    void lock()
-    {
-        volatile dword count = 0;
-        for (;;) {
-            if (CAS(&m_lock, 1, 0) == 1)
-                return;
-            ++count;
-
-        }
-        if (count)
-            kprintf("waited %u in %s\n",count, current->name().characters());
-    }
-
-    void unlock()
-    {
-        // barrier();
-        m_lock = 0;
-    }
-
-private:
-    dword m_lock { 0 };
-};
-
-class Locker {
-public:
-    explicit Locker(SpinLock& l)
-        : m_lock(l)
-    {
-        m_lock.lock();
-    }
-
-    ~Locker()
-    {
-        unlock();
-    }
-
-    void unlock()
-    {
-        m_lock.unlock();
-    }
-
-private:
-    SpinLock& m_lock;
-};
-
 namespace Syscall {
 
 static SpinLock* s_lock;

Kernel/Task.cpp

@@ -494,28 +494,6 @@ bool scheduleNewTask()
     }
 }
 
-static void drawSchedulerBanner(Task& task)
-{
-    return;
-    // FIXME: We need a kernel lock to do stuff like this :(
-    //return;
-    auto c = vga_get_cursor();
-    auto a = vga_get_attr();
-    vga_set_cursor(0, 50);
-    vga_set_attr(0x20);
-    kprintf("          ");
-    kprintf("          ");
-    kprintf("          ");
-    vga_set_cursor(0, 50);
-    kprintf("pid: %u ", task.pid());
-    vga_set_cursor(0, 58);
-    kprintf("%s", task.name().characters());
-    vga_set_cursor(0, 65);
-    kprintf("eip: %p", task.tss().eip);
-    vga_set_attr(a);
-    vga_set_cursor(c);
-}
-
 static bool contextSwitch(Task* t)
 {
     //kprintf("c_s to %s (same:%u)\n", t->name().characters(), current == t);
@@ -573,7 +551,6 @@ static bool contextSwitch(Task* t)
     tssDescriptor.type = 11; // Busy TSS
 
     flushGDT();
-    drawSchedulerBanner(*t);
 
     t->didSchedule();
     return true;

Kernel/VGA.cpp

@@ -33,22 +33,15 @@ byte vga_get_attr()
 
 void vga_init()
 {
-    DWORD i;
-
     current_attr = 0x07;
-    vga_mem = (BYTE *)0xb8000;
+    vga_mem = (byte*)0xb8000;
 
-    for (i = 0; i < (80 * 24); ++i) {
+    for (word i = 0; i < (80 * 25); ++i) {
         vga_mem[i*2] = ' ';
         vga_mem[i*2 + 1] = 0x07;
     }
 
-    // Fill the bottom line with blue.
-    for (i = (80 * 24); i < (80 * 25); ++i) {
-        vga_mem[i*2] = ' ';
-        vga_mem[i*2 + 1] = 0x17;
-    }
-    vga_set_cursor( 0 );
+    vga_set_cursor(0);
 }
 
 WORD vga_get_cursor()

Kernel/i8253.cpp

@@ -95,23 +95,6 @@ void clock_handle()
     current->tss().cs = regs.cs;
     current->tss().eflags = regs.eflags;
 
-#if 0
-    BYTE a = vga_get_attr();
-    WORD foo = vga_get_cursor();
-
-    vga_set_attr(0x50);
-    vga_set_cursor(0);
-
-    kprintf("\n\n");
-    kprintf("Task %u interrupted at %x             \n", current->pid(), regs.eip );
-    kprintf("EAX=%x EBX=%x ECX=%x EDX=%x           \n", regs.eax, regs.ebx, regs.ecx, regs.edx);
-    kprintf("ESI=%x EDI=%x EBP=%x ESP=%x           \n", regs.esi, regs.edi, regs.ebp, regs.esp);
-    kprintf("FLAGS=%x", regs.eflags);
-
-    vga_set_cursor(foo);
-    vga_set_attr(a);
-#endif
-
     // Compute task ESP.
     // Add 12 for CS, EIP, EFLAGS (interrupt mechanic)
 

Kernel/init.cpp

@@ -32,53 +32,6 @@
 //#define TEST_ELF_LOADER
 //#define TEST_CRASHY_USER_PROCESSES
 
-static void motd_main() NORETURN;
-static void motd_main()
-{
-    kprintf("Hello in motd_main!\n");
-    int fd = Userspace::open("/test.asm");
-    kprintf("motd: fd=%d\n", fd);
-    ASSERT(fd != -1);
-    DO_SYSCALL_A3(0x2000, 1, 2, 3);
-    kprintf("getuid(): %u\n", Userspace::getuid());
-    auto buffer = DataBuffer::createUninitialized(33);
-    memset(buffer->data(), 0, buffer->length());
-    int nread = Userspace::read(fd, buffer->data(), buffer->length() - 1);
-    kprintf("read(): %d\n", nread);
-    buffer->data()[nread] = 0;
-    kprintf("read(): '%s'\n", buffer->data());
-    for (;;) {
-        //kill(4, 5);
-        sleep(1 * TICKS_PER_SECOND);
-    }
-}
-
-static void syscall_test_main() NORETURN;
-static void syscall_test_main()
-{
-    kprintf("Hello in syscall_test_main!\n");
-    for (;;) {
-        Userspace::getuid();
-//        Userspace::yield();
-        //kprintf("getuid(): %u\n", Userspace::getuid());
-        sleep(1 * TICKS_PER_SECOND);
-    }
-}
-
-static void user_main() NORETURN;
-static void user_main()
-{
-    DO_SYSCALL_A3(0x3000, 2, 3, 4);
-    // Crash ourselves!
-    char* x = reinterpret_cast<char*>(0xbeefbabe);
-    *x = 1;
-    HANG;
-    for (;;) {
-        // nothing?
-        Userspace::sleep(1 * TICKS_PER_SECOND);
-    }
-}
-
 system_t system;
 
 void banner()
@@ -192,10 +145,7 @@ static void init_stage2()
 
     auto* shTask = Task::create("/bin/sh", (uid_t)100, (gid_t)100);
 
-    //new Task(motd_main, "motd", IPC::Handle::MotdTask, Task::Ring0);
-    //new Task(syscall_test_main, "syscall_test", IPC::Handle::MotdTask, Task::Ring3);
-
-    kprintf("init stage2 is done!\n");
+    banner();
 
 #if 0
     // It would be nice to exit this process, but right now it instantiates all kinds of things.