Merge tag 'driver-core-5.0-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git...

[sfrench/cifs-2.6.git] / arch / xtensa / kernel / smp.c

diff --git a/arch/xtensa/kernel/smp.c b/arch/xtensa/kernel/smp.c
index 932d64689bacbbbf3dc2ae981b3d3d1938172bce..be1f280c322cd17307e0377736abdb3d955e3ebc 100644 (file)
--- a/arch/xtensa/kernel/smp.c
+++ b/arch/xtensa/kernel/smp.c
@@ -83,7 +83,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 {
        unsigned i;
 
-       for (i = 0; i < max_cpus; ++i)
+       for_each_possible_cpu(i)
                set_cpu_present(i, true);
 }
 
@@ -96,6 +96,11 @@ void __init smp_init_cpus(void)
        pr_info("%s: Core Count = %d\n", __func__, ncpus);
        pr_info("%s: Core Id = %d\n", __func__, core_id);
 
+       if (ncpus > NR_CPUS) {
+               ncpus = NR_CPUS;
+               pr_info("%s: limiting core count by %d\n", __func__, ncpus);
+       }
+
        for (i = 0; i < ncpus; ++i)
                set_cpu_possible(i, true);
 }
@@ -195,9 +200,11 @@ static int boot_secondary(unsigned int cpu, struct task_struct *ts)
        int i;
 
 #ifdef CONFIG_HOTPLUG_CPU
-       cpu_start_id = cpu;
-       system_flush_invalidate_dcache_range(
-                       (unsigned long)&cpu_start_id, sizeof(cpu_start_id));
+       WRITE_ONCE(cpu_start_id, cpu);
+       /* Pairs with the third memw in the cpu_restart */
+       mb();
+       system_flush_invalidate_dcache_range((unsigned long)&cpu_start_id,
+                                            sizeof(cpu_start_id));
 #endif
        smp_call_function_single(0, mx_cpu_start, (void *)cpu, 1);
 
@@ -206,18 +213,21 @@ static int boot_secondary(unsigned int cpu, struct task_struct *ts)
                        ccount = get_ccount();
                while (!ccount);
 
-               cpu_start_ccount = ccount;
+               WRITE_ONCE(cpu_start_ccount, ccount);
 
-               while (time_before(jiffies, timeout)) {
+               do {
+                       /*
+                        * Pairs with the first two memws in the
+                        * .Lboot_secondary.
+                        */
                        mb();
-                       if (!cpu_start_ccount)
-                               break;
-               }
+                       ccount = READ_ONCE(cpu_start_ccount);
+               } while (ccount && time_before(jiffies, timeout));
 
-               if (cpu_start_ccount) {
+               if (ccount) {
                        smp_call_function_single(0, mx_cpu_stop,
-                                       (void *)cpu, 1);
-                       cpu_start_ccount = 0;
+                                                (void *)cpu, 1);
+                       WRITE_ONCE(cpu_start_ccount, 0);
                        return -EIO;
                }
        }
@@ -237,6 +247,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
        pr_debug("%s: Calling wakeup_secondary(cpu:%d, idle:%p, sp: %08lx)\n",
                        __func__, cpu, idle, start_info.stack);
 
+       init_completion(&cpu_running);
        ret = boot_secondary(cpu, idle);
        if (ret == 0) {
                wait_for_completion_timeout(&cpu_running,
@@ -298,8 +309,10 @@ void __cpu_die(unsigned int cpu)
        unsigned long timeout = jiffies + msecs_to_jiffies(1000);
        while (time_before(jiffies, timeout)) {
                system_invalidate_dcache_range((unsigned long)&cpu_start_id,
-                               sizeof(cpu_start_id));
-               if (cpu_start_id == -cpu) {
+                                              sizeof(cpu_start_id));
+               /* Pairs with the second memw in the cpu_restart */
+               mb();
+               if (READ_ONCE(cpu_start_id) == -cpu) {
                        platform_cpu_kill(cpu);
                        return;
                }