Way tighter locking in process creation.

We no longer disable interrupts around the whole affair.
Since MM manages per-process data structures, this works quite smoothly now.
Only procfs had to be tweaked with an InterruptDisabler.

Kernel/ProcFileSystem.cpp

@@ -116,7 +116,7 @@ ByteBuffer procfs$pid_exe(Process& process)
 
 void ProcFileSystem::addProcess(Process& process)
 {
-    ASSERT_INTERRUPTS_DISABLED();
+    InterruptDisabler disabler;
     char buf[16];
     ksprintf(buf, "%d", process.pid());
     auto dir = addFile(createDirectory(buf));
@@ -130,7 +130,7 @@ void ProcFileSystem::addProcess(Process& process)
 
 void ProcFileSystem::removeProcess(Process& process)
 {
-    ASSERT_INTERRUPTS_DISABLED();
+    InterruptDisabler disabler;
     auto pid = process.pid();
     auto it = m_pid2inode.find(pid);
     ASSERT(it != m_pid2inode.end());

Kernel/Process.cpp

@@ -86,13 +86,20 @@ void Process::prepForIRETToNewProcess()
     loadTaskRegister(s_kernelProcess->selector());
 }
 
+static void hlt_loop()
+{
+    for (;;) {
+        asm volatile("hlt");
+    }
+}
+
 void Process::initialize()
 {
     current = nullptr;
     next_pid = 0;
     s_processes = new InlineLinkedList<Process>;
     s_deadProcesses = new InlineLinkedList<Process>;
-    s_kernelProcess = Process::createKernelProcess(nullptr, "colonel");
+    s_kernelProcess = Process::createKernelProcess(hlt_loop, "colonel");
     s_hostname = new String("birx");
     redoKernelProcessTSS();
     loadTaskRegister(s_kernelProcess->selector());
@@ -271,18 +278,16 @@ Process* Process::createUserProcess(const String& path, uid_t uid, gid_t gid, pi
     processEnvironment.append("TERM=console");
     processEnvironment.append("HOME=/");
 
-    InterruptDisabler disabler; // FIXME: Get rid of this, jesus christ. This "critical" section is HUGE.
+    auto* t = new Process(parts.takeLast(), uid, gid, parentPID, Ring3, move(cwd), handle->vnode(), tty);
-    KernelPagingScope pagingScope;
-    Process* t = new Process(parts.takeLast(), uid, gid, parentPID, Ring3, move(cwd), handle->vnode(), tty);
 
     t->m_arguments = move(processArguments);
     t->m_initialEnvironment = move(processEnvironment);
 
     ExecSpace space;
     Region* region = nullptr;
-
     byte* region_alias = nullptr;
 
+    KernelPagingScope pagingScope;
     space.hookableAlloc = [&] (const String& name, size_t size) {
         if (!size)
             return (void*)nullptr;
@@ -330,6 +335,8 @@ Process* Process::createUserProcess(const String& path, uid_t uid, gid_t gid, pi
     ASSERT(region);
     MM.remove_kernel_alias_for_region(*region, region_alias);
 
+    ProcFileSystem::the().addProcess(*t);
+
     s_processes->prepend(t);
     system.nprocess++;
 #ifdef TASK_DEBUG
@@ -379,13 +386,14 @@ int Process::sys$get_arguments(int* argc, char*** argv)
 
 Process* Process::createKernelProcess(void (*e)(), String&& name)
 {
-    Process* process = new Process(move(name), (uid_t)0, (gid_t)0, (pid_t)0, Ring0);
+    auto* process = new Process(move(name), (uid_t)0, (gid_t)0, (pid_t)0, Ring0);
     process->m_tss.eip = (dword)e;
 
     if (process->pid() != 0) {
         InterruptDisabler disabler;
         s_processes->prepend(process);
         system.nprocess++;
+        ProcFileSystem::the().addProcess(*process);
 #ifdef TASK_DEBUG
         kprintf("Kernel process %u (%s) spawned @ %p\n", process->pid(), process->name().characters(), process->m_tss.eip);
 #endif
@@ -474,8 +482,6 @@ Process::Process(String&& name, uid_t uid, gid_t gid, pid_t parentPID, RingLevel
     // HACK: Ring2 SS in the TSS is the current PID.
     m_tss.ss2 = m_pid;
     m_farPtr.offset = 0x98765432;
-
-    ProcFileSystem::the().addProcess(*this);
 }
 
 Process::~Process()
@@ -707,7 +713,7 @@ bool scheduleNewProcess()
                     process->timesScheduled(),
                     process->name().characters());
             }
-            kprintf("Switch to kernel process\n");
+            kprintf("Switch to kernel process @ %w:%x\n", s_kernelProcess->tss().cs, s_kernelProcess->tss().eip);
             return contextSwitch(Process::kernelProcess());
         }
     }

Kernel/init.cpp

@@ -101,6 +101,25 @@ static void undertaker_main()
     }
 }
 
+static void spawn_stress() NORETURN;
+static void spawn_stress()
+{
+    dword lastAlloc = sum_alloc;
+
+    for (unsigned i = 0; i < 100; ++i) {
+        int error;
+        Process::createUserProcess("/bin/id", (uid_t)100, (gid_t)100, (pid_t)0, error, nullptr, tty0);
+        kprintf("malloc stats: alloc:%u free:%u\n", sum_alloc, sum_free);
+        kprintf("delta:%u\n", sum_alloc - lastAlloc);
+        lastAlloc = sum_alloc;
+        sleep(600);
+    }
+    for (;;) {
+        asm volatile("hlt");
+    }
+}
+
+
 static void init_stage2() NORETURN;
 static void init_stage2()
 {
@@ -173,20 +192,6 @@ static void init_stage2()
     }
 #endif
 
-#ifdef STRESS_TEST_SPAWNING
-    dword lastAlloc = sum_alloc;
-
-    for (unsigned i = 0; i < 100; ++i) {
-        int error;
-        auto* shProcess = Process::createUserProcess("/bin/id", (uid_t)100, (gid_t)100, (pid_t)0, error);
-        kprintf("malloc stats: alloc:%u free:%u\n", sum_alloc, sum_free);
-        kprintf("sizeof(Process):%u\n", sizeof(Process));
-        kprintf("delta:%u\n",sum_alloc - lastAlloc);
-        lastAlloc = sum_alloc;
-        sleep(600);
-    }
-#endif
-
     int error;
     auto* sh0 = Process::createUserProcess("/bin/sh", (uid_t)100, (gid_t)100, (pid_t)0, error, nullptr, tty0);
 #ifdef SPAWN_MULTIPLE_SHELLS
@@ -195,6 +200,10 @@ static void init_stage2()
     auto* sh3 = Process::createUserProcess("/bin/sh", (uid_t)100, (gid_t)100, (pid_t)0, error, nullptr, tty3);
 #endif
 
+#ifdef STRESS_TEST_SPAWNING
+    Process::createKernelProcess(spawn_stress, "spawn_stress");
+#endif
+
 #if 0
     // It would be nice to exit this process, but right now it instantiates all kinds of things.
     // At the very least it needs to be made sure those things stick around as appropriate.