[MIPS] SMP: Fix initialization order bug.

    
A recent change requires cpu_possible_map to be initialized before
smp_sched_init() but most MIPS platforms were initializing their
processors in the prom_prepare_cpus callback of smp_prepare_cpus.  The
simple fix of calling prom_prepare_cpus from one of the earlier SMP
initialization hooks doesn't work well either since IPIs may require
init_IRQ() to have completed, so bit the bullet and split
prom_prepare_cpus into two initialization functions, plat_smp_setup
which is called early from setup_arch and plat_prepare_cpus called where
prom_prepare_cpus used to be called.
    
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

7 files changed, 39 insertions, 31 deletions

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index d86affa21278..d9293c558e41 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -540,6 +540,9 @@ void __init setup_arch(char **cmdline_p)
         sparse_init();
         paging_init();
         resource_init();
+#ifdef CONFIG_SMP
+        plat_smp_setup();
+#endif
 }
 
 int __init fpu_disable(char *s)
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 5e189862e523..06ed90752424 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -236,7 +236,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
         init_new_context(current, &init_mm);
         current_thread_info()->cpu = 0;
         smp_tune_scheduling();
-        prom_prepare_cpus(max_cpus);
+        plat_prepare_cpus(max_cpus);
 }
 
 /* preload SMP state for boot cpu */
diff --git a/arch/mips/kernel/smp_mt.c b/arch/mips/kernel/smp_mt.c
index c930364830d0..993b8bf56aaf 100644
--- a/arch/mips/kernel/smp_mt.c
+++ b/arch/mips/kernel/smp_mt.c
@@ -143,7 +143,7 @@ static struct irqaction irq_call = {
  * Make sure all CPU's are in a sensible state before we boot any of the
  * secondarys
  */
-void prom_prepare_cpus(unsigned int max_cpus)
+void plat_smp_setup(void)
 {
         unsigned long val;
         int i, num;
@@ -179,11 +179,9 @@ void prom_prepare_cpus(unsigned int max_cpus)
                                 write_vpe_c0_vpeconf0(tmp);
 
                                 /* Record this as available CPU */
-                                if (i < max_cpus) {
-                                        cpu_set(i, phys_cpu_present_map);
-                                        __cpu_number_map[i]     = ++num;
-                                        __cpu_logical_map[num]  = i;
-                                }
+                                cpu_set(i, phys_cpu_present_map);
+                                __cpu_number_map[i]     = ++num;
+                                __cpu_logical_map[num]  = i;
                         }
 
                         /* disable multi-threading with TC's */
@@ -241,7 +239,10 @@ void prom_prepare_cpus(unsigned int max_cpus)
                 set_vi_handler (MIPS_CPU_IPI_RESCHED_IRQ, ipi_resched_dispatch);
                 set_vi_handler (MIPS_CPU_IPI_CALL_IRQ, ipi_call_dispatch);
         }
+}
 
+void __init plat_prepare_cpus(unsigned int max_cpus)
+{
         cpu_ipi_resched_irq = MIPSCPU_INT_BASE + MIPS_CPU_IPI_RESCHED_IRQ;
         cpu_ipi_call_irq = MIPSCPU_INT_BASE + MIPS_CPU_IPI_CALL_IRQ;
 
diff --git a/arch/mips/pmc-sierra/yosemite/smp.c b/arch/mips/pmc-sierra/yosemite/smp.c
index 7f8fda962190..c197311e15d3 100644
--- a/arch/mips/pmc-sierra/yosemite/smp.c
+++ b/arch/mips/pmc-sierra/yosemite/smp.c
@@ -50,37 +50,25 @@ void __init prom_grab_secondary(void)
  * We don't want to start the secondary CPU yet nor do we have a nice probing
  * feature in PMON so we just assume presence of the secondary core.
  */
-static char maxcpus_string[] __initdata =
-        KERN_WARNING "max_cpus set to 0; using 1 instead\n";
-
-void __init prom_prepare_cpus(unsigned int max_cpus)
+void __init plat_smp_setup(void)
 {
-        int enabled = 0, i;
-
-        if (max_cpus == 0) {
-                printk(maxcpus_string);
-                max_cpus = 1;
-        }
+        int i;
 
         cpus_clear(phys_cpu_present_map);
 
         for (i = 0; i < 2; i++) {
-                if (i == max_cpus)
-                        break;
-
-                /*
-                 * The boot CPU
-                 */
                 cpu_set(i, phys_cpu_present_map);
                 __cpu_number_map[i]     = i;
                 __cpu_logical_map[i]    = i;
-                enabled++;
         }
+}
 
+void __init plat_prepare_cpus(unsigned int max_cpus)
+{
         /*
          * Be paranoid.  Enable the IPI only if we're really about to go SMP.
          */
-        if (enabled > 1)
+        if (cpus_weight(cpu_possible_map))
                 set_c0_status(STATUSF_IP5);
 }
 
diff --git a/arch/mips/sgi-ip27/ip27-smp.c b/arch/mips/sgi-ip27/ip27-smp.c
index dbef3f6b5650..09fa7f5216f0 100644
--- a/arch/mips/sgi-ip27/ip27-smp.c
+++ b/arch/mips/sgi-ip27/ip27-smp.c
@@ -140,7 +140,7 @@ static __init void intr_clear_all(nasid_t nasid)
                 REMOTE_HUB_CLR_INTR(nasid, i);
 }
 
-void __init prom_prepare_cpus(unsigned int max_cpus)
+void __init plat_smp_setup(void)
 {
         cnodeid_t       cnode;
 
@@ -161,6 +161,11 @@ void __init prom_prepare_cpus(unsigned int max_cpus)
         alloc_cpupda(0, 0);
 }
 
+void __init plat_prepare_cpus(unsigned int max_cpus)
+{
+        /* We already did everything necessary earlier */
+}
+
 /*
  * Launch a slave into smp_bootstrap().  It doesn't take an argument, and we
  * set sp to the kernel stack of the newly created idle process, gp to the proc
diff --git a/arch/mips/sibyte/cfe/smp.c b/arch/mips/sibyte/cfe/smp.c
index 4477af3d8074..eab20e2db323 100644
--- a/arch/mips/sibyte/cfe/smp.c
+++ b/arch/mips/sibyte/cfe/smp.c
@@ -31,7 +31,7 @@
  *
  * Common setup before any secondaries are started
  */
-void __init prom_prepare_cpus(unsigned int max_cpus)
+void __init plat_smp_setup(void)
 {
         int i, num;
 
@@ -40,14 +40,18 @@ void __init prom_prepare_cpus(unsigned int max_cpus)
         __cpu_number_map[0] = 0;
         __cpu_logical_map[0] = 0;
 
-        for (i=1, num=0; i<NR_CPUS; i++) {
+        for (i = 1, num = 0; i < NR_CPUS; i++) {
                 if (cfe_cpu_stop(i) == 0) {
                         cpu_set(i, phys_cpu_present_map);
                         __cpu_number_map[i] = ++num;
                         __cpu_logical_map[num] = i;
                 }
         }
-        printk("Detected %i available secondary CPU(s)\n", num);
+        printk(KERN_INFO "Detected %i available secondary CPU(s)\n", num);
+}
+
+void __init plat_prepare_cpus(unsigned int max_cpus)
+{
 }
 
 /*
diff --git a/include/asm-mips/smp.h b/include/asm-mips/smp.h
index 5618f1e12f40..75c6fe7c2126 100644
--- a/include/asm-mips/smp.h
+++ b/include/asm-mips/smp.h
@@ -58,7 +58,9 @@ static inline int num_booting_cpus(void)
         return cpus_weight(cpu_callout_map);
 }
 
-/* These are defined by the board-specific code. */
+/*
+ * These are defined by the board-specific code.
+ */
 
 /*
  * Cause the function described by call_data to be executed on the passed
@@ -79,7 +81,12 @@ extern void prom_boot_secondary(int cpu, struct task_struct *idle);
 extern void prom_init_secondary(void);
 
 /*
- * Detect available CPUs, populate phys_cpu_present_map before smp_init
+ * Populate cpu_possible_map before smp_init, called from setup_arch.
+ */
+extern void plat_smp_setup(void);
+
+/*
+ * Called after init_IRQ but before __cpu_up.
  */
 extern void prom_prepare_cpus(unsigned int max_cpus);