um: Stop tracking host PID in cpu_tasks

The host PID tracked in 'cpu_tasks' is no longer used. Stopping
tracking it will also save some cycles.
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/include/shared/as-layout.h

@@ -31,7 +31,6 @@
 #include <sysdep/ptrace.h>
 
 struct cpu_task {
-	int pid;
 	void *task;
 };
 

arch/um/kernel/process.c

@@ -43,13 +43,7 @@
  * cares about its entry, so it's OK if another processor is modifying its
  * entry.
  */
-struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
-
-static inline int external_pid(void)
-{
-	/* FIXME: Need to look up userspace_pid by cpu */
-	return userspace_pid[0];
-}
+struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { NULL } };
 
 void free_stack(unsigned long stack, int order)
 {
@@ -70,8 +64,7 @@ unsigned long alloc_stack(int order, int atomic)
 
 static inline void set_current(struct task_struct *task)
 {
-	cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
-		{ external_pid(), task });
+	cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task) { task });
 }
 
 struct task_struct *__switch_to(struct task_struct *from, struct task_struct *to)
@@ -206,7 +199,6 @@ void um_idle_sleep(void)
 
 void arch_cpu_idle(void)
 {
-	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 	um_idle_sleep();
 }
 

arch/um/kernel/skas/process.c

@@ -18,12 +18,8 @@ extern void start_kernel(void);
 
 static int __init start_kernel_proc(void *unused)
 {
-	int pid;
-
 	block_signals_trace();
-	pid = os_getpid();
 
-	cpu_tasks[0].pid = pid;
 	cpu_tasks[0].task = current;
 
 	start_kernel();