MIPS: SMP: Fix build error.

  CC      arch/mips/kernel/smp.o
arch/mips/kernel/smp.c: In function ‘start_secondary’:
arch/mips/kernel/smp.c:149:2: error: passing argument 2 of ‘cpumask_set_cpu’ discards ‘volatile’ qualifier from pointer target type [-Werror]
  cpumask_set_cpu(cpu, &cpu_callin_map);
  ^
In file included from ./arch/mips/include/asm/processor.h:14:0,
                 from ./arch/mips/include/asm/thread_info.h:15,
                 from include/linux/thread_info.h:54,
                 from include/asm-generic/preempt.h:4,
                 from arch/mips/include/generated/asm/preempt.h:1,
                 from include/linux/preempt.h:18,
                 from include/linux/interrupt.h:8,
                 from arch/mips/kernel/smp.c:24:
include/linux/cpumask.h:272:91: note: expected ‘struct cpumask *’ but argument is of type ‘volatile struct cpumask_t *’
 static inline void cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
                                                                                           ^
arch/mips/kernel/smp.c: In function ‘smp_prepare_boot_cpu’:
arch/mips/kernel/smp.c:211:2: error: passing argument 2 of ‘cpumask_set_cpu’ discards ‘volatile’ qualifier from pointer target type [-Werror]
  cpumask_set_cpu(0, &cpu_callin_map);
  ^
In file included from ./arch/mips/include/asm/processor.h:14:0,
                 from ./arch/mips/include/asm/thread_info.h:15,
                 from include/linux/thread_info.h:54,
                 from include/asm-generic/preempt.h:4,
                 from arch/mips/include/generated/asm/preempt.h:1,
                 from include/linux/preempt.h:18,
                 from include/linux/interrupt.h:8,
                 from arch/mips/kernel/smp.c:24:
include/linux/cpumask.h:272:91: note: expected ‘struct cpumask *’ but argument is of type ‘volatile struct cpumask_t *’
 static inline void cpumask_set_cpu(unsigned int cpu, struct cpumask *dstp)
                                                                                           ^
arch/mips/kernel/smp.c: In function ‘__cpu_up’:
arch/mips/kernel/smp.c:221:10: error: passing argument 2 of ‘cpumask_test_cpu’ discards ‘volatile’ qualifier from pointer target type [-Werror]
  while (!cpumask_test_cpu(cpu, &cpu_callin_map))
          ^
In file included from ./arch/mips/include/asm/processor.h:14:0,
                 from ./arch/mips/include/asm/thread_info.h:15,
                 from include/linux/thread_info.h:54,
                 from include/asm-generic/preempt.h:4,
                 from arch/mips/include/generated/asm/preempt.h:1,
                 from include/linux/preempt.h:18,
                 from include/linux/interrupt.h:8,
                 from arch/mips/kernel/smp.c:24:
include/linux/cpumask.h:294:90: note: expected ‘const struct cpumask *’ but argument is of type ‘volatile struct cpumask_t *’
 static inline int cpumask_test_cpu(int cpu, const struct cpumask *cpumask)
                                                                                          ^
cc1: all warnings being treated as errors
make[2]: *** [arch/mips/kernel/smp.o] Error 1
make[1]: *** [arch/mips/kernel] Error 2
make: *** [arch/mips] Error 2
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/smp.h

@@ -45,7 +45,7 @@ extern int __cpu_logical_map[NR_CPUS];
 #define SMP_DUMP		0x8
 #define SMP_ASK_C0COUNT		0x10
 
-extern volatile cpumask_t cpu_callin_map;
+extern cpumask_t cpu_callin_map;
 
 /* Mask of CPUs which are currently definitely operating coherently */
 extern cpumask_t cpu_coherent_mask;

arch/mips/kernel/smp.c

@@ -43,7 +43,7 @@
 #include <asm/time.h>
 #include <asm/setup.h>
 
-volatile cpumask_t cpu_callin_map;	/* Bitmask of started secondaries */
+cpumask_t cpu_callin_map;		/* Bitmask of started secondaries */
 
 int __cpu_number_map[NR_CPUS];		/* Map physical to logical */
 EXPORT_SYMBOL(__cpu_number_map);
@@ -218,8 +218,10 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 	/*
 	 * Trust is futile.  We should really have timeouts ...
 	 */
-	while (!cpumask_test_cpu(cpu, &cpu_callin_map))
+	while (!cpumask_test_cpu(cpu, &cpu_callin_map)) {
 		udelay(100);
+		schedule();
+	}
 
 	synchronise_count_master(cpu);
 	return 0;