um: Remove broken SMP support

At times where UML used the TT mode to operate it had
kind of SMP support. It never got finished nor was
stable.
Let's rip out that cruft and stop confusing developers
which do tree-wide SMP cleanups.

If someone wants SMP support UML it has do be done from scratch.

Signed-off-by: Richard Weinberger <[email protected]>

Author: richardweinberger

arch/um/Kconfig.um

@@ -95,36 +95,6 @@ config MAGIC_SYSRQ
 	  The keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
 	  unless you really know what this hack does.
 
-config SMP
-	bool "Symmetric multi-processing support"
-	default n
-	depends on BROKEN
-	help
-	  This option enables UML SMP support.
-	  It is NOT related to having a real SMP box. Not directly, at least.
-
-	  UML implements virtual SMP by allowing as many processes to run
-	  simultaneously on the host as there are virtual processors configured.
-
-	  Obviously, if the host is a uniprocessor, those processes will
-	  timeshare, but, inside UML, will appear to be running simultaneously.
-	  If the host is a multiprocessor, then UML processes may run
-	  simultaneously, depending on the host scheduler.
-
-	  This, however, is supported only in TT mode. So, if you use the SKAS
-	  patch on your host, switching to TT mode and enabling SMP usually
-	  gives	you worse performances.
-	  Also, since the support for SMP has been under-developed, there could
-	  be some bugs being exposed by enabling SMP.
-
-	  If you don't know what to do, say N.
-
-config NR_CPUS
-	int "Maximum number of CPUs (2-32)"
-	range 2 32
-	depends on SMP
-	default "32"
-
 config HIGHMEM
 	bool "Highmem support"
 	depends on !64BIT && BROKEN

arch/um/include/asm/processor-generic.h

@@ -98,16 +98,8 @@ struct cpuinfo_um {
 
 extern struct cpuinfo_um boot_cpu_data;
 
-#define my_cpu_data		cpu_data[smp_processor_id()]
-
-#ifdef CONFIG_SMP
-extern struct cpuinfo_um cpu_data[];
-#define current_cpu_data cpu_data[smp_processor_id()]
-#else
 #define cpu_data (&boot_cpu_data)
 #define current_cpu_data boot_cpu_data
-#endif
-
 
 #define KSTK_REG(tsk, reg) get_thread_reg(reg, &tsk->thread.switch_buf)
 extern unsigned long get_wchan(struct task_struct *p);

arch/um/include/asm/smp.h

@@ -1,32 +1,6 @@
 #ifndef __UM_SMP_H
 #define __UM_SMP_H
 
-#ifdef CONFIG_SMP
-
-#include <linux/bitops.h>
-#include <asm/current.h>
-#include <linux/cpumask.h>
-
-#define raw_smp_processor_id() (current_thread->cpu)
-
-#define cpu_logical_map(n) (n)
-#define cpu_number_map(n) (n)
-extern int hard_smp_processor_id(void);
-#define NO_PROC_ID -1
-
-extern int ncpus;
-
-
-static inline void smp_cpus_done(unsigned int maxcpus)
-{
-}
-
-extern struct task_struct *idle_threads[NR_CPUS];
-
-#else
-
 #define hard_smp_processor_id()		0
 
 #endif
-
-#endif

arch/um/kernel/Makefile

@@ -12,7 +12,7 @@ clean-files :=
 
 obj-y = config.o exec.o exitcode.o irq.o ksyms.o mem.o \
 	physmem.o process.o ptrace.o reboot.o sigio.o \
-	signal.o smp.o syscall.o sysrq.o time.o tlb.o trap.o \
+	signal.o syscall.o sysrq.o time.o tlb.o trap.o \
 	um_arch.o umid.o maccess.o skas/
 
 obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o

arch/um/kernel/irq.c

@@ -35,9 +35,6 @@ void sigio_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
 	struct irq_fd *irq_fd;
 	int n;
 
-	if (smp_sigio_handler())
-		return;
-
 	while (1) {
 		n = os_waiting_for_events(active_fds);
 		if (n <= 0) {

arch/um/kernel/process.c

@@ -259,17 +259,6 @@ int strlen_user_proc(char __user *str)
 	return strlen_user(str);
 }
 
-int smp_sigio_handler(void)
-{
-#ifdef CONFIG_SMP
-	int cpu = current_thread_info()->cpu;
-	IPI_handler(cpu);
-	if (cpu != 0)
-		return 1;
-#endif
-	return 0;
-}
-
 int cpu(void)
 {
 	return current_thread_info()->cpu;

arch/um/kernel/skas/process.c

@@ -21,9 +21,7 @@ static int __init start_kernel_proc(void *unused)
 
 	cpu_tasks[0].pid = pid;
 	cpu_tasks[0].task = current;
-#ifdef CONFIG_SMP
-	init_cpu_online(get_cpu_mask(0));
-#endif
+
 	start_kernel();
 	return 0;
 }