Merge tag 'v2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

[mv-sheeva.git] / kernel / smp.c

diff --git a/kernel/smp.c b/kernel/smp.c
index 12ed8b013e2d7cd8be438a808f3a6981ab4cd70a..9910744f0856c5a084b4f9721dca09f376415645 100644 (file)
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -13,6 +13,7 @@
 #include <linux/smp.h>
 #include <linux/cpu.h>
 
+#ifdef CONFIG_USE_GENERIC_SMP_HELPERS
 static struct {
        struct list_head        queue;
        raw_spinlock_t          lock;
@@ -193,23 +194,52 @@ void generic_smp_call_function_interrupt(void)
         */
        list_for_each_entry_rcu(data, &call_function.queue, csd.list) {
                int refs;
+               void (*func) (void *info);
 
-               if (!cpumask_test_and_clear_cpu(cpu, data->cpumask))
+               /*
+                * Since we walk the list without any locks, we might
+                * see an entry that was completed, removed from the
+                * list and is in the process of being reused.
+                *
+                * We must check that the cpu is in the cpumask before
+                * checking the refs, and both must be set before
+                * executing the callback on this cpu.
+                */
+
+               if (!cpumask_test_cpu(cpu, data->cpumask))
+                       continue;
+
+               smp_rmb();
+
+               if (atomic_read(&data->refs) == 0)
                        continue;
 
+               func = data->csd.func;                  /* for later warn */
                data->csd.func(data->csd.info);
 
+               /*
+                * If the cpu mask is not still set then it enabled interrupts,
+                * we took another smp interrupt, and executed the function
+                * twice on this cpu.  In theory that copy decremented refs.
+                */
+               if (!cpumask_test_and_clear_cpu(cpu, data->cpumask)) {
+                       WARN(1, "%pS enabled interrupts and double executed\n",
+                            func);
+                       continue;
+               }
+
                refs = atomic_dec_return(&data->refs);
                WARN_ON(refs < 0);
-               if (!refs) {
-                       raw_spin_lock(&call_function.lock);
-                       list_del_rcu(&data->csd.list);
-                       raw_spin_unlock(&call_function.lock);
-               }
 
                if (refs)
                        continue;
 
+               WARN_ON(!cpumask_empty(data->cpumask));
+
+               raw_spin_lock(&call_function.lock);
+               list_del_rcu(&data->csd.list);
+               raw_spin_unlock(&call_function.lock);
+
                csd_unlock(&data->csd);
        }
 
@@ -429,7 +459,7 @@ void smp_call_function_many(const struct cpumask *mask,
         * can't happen.
         */
        WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
-                    && !oops_in_progress);
+                    && !oops_in_progress && !early_boot_irqs_disabled);
 
        /* So, what's a CPU they want? Ignoring this one. */
        cpu = cpumask_first_and(mask, cpu_online_mask);
@@ -453,11 +483,21 @@ void smp_call_function_many(const struct cpumask *mask,
 
        data = &__get_cpu_var(cfd_data);
        csd_lock(&data->csd);
+       BUG_ON(atomic_read(&data->refs) || !cpumask_empty(data->cpumask));
 
        data->csd.func = func;
        data->csd.info = info;
        cpumask_and(data->cpumask, mask, cpu_online_mask);
        cpumask_clear_cpu(this_cpu, data->cpumask);
+
+       /*
+        * To ensure the interrupt handler gets an complete view
+        * we order the cpumask and refs writes and order the read
+        * of them in the interrupt handler.  In addition we may
+        * only clear our own cpu bit from the mask.
+        */
+       smp_wmb();
+
        atomic_set(&data->refs, cpumask_weight(data->cpumask));
 
        raw_spin_lock_irqsave(&call_function.lock, flags);
@@ -529,3 +569,24 @@ void ipi_call_unlock_irq(void)
 {
        raw_spin_unlock_irq(&call_function.lock);
 }
+#endif /* USE_GENERIC_SMP_HELPERS */
+
+/*
+ * Call a function on all processors.  May be used during early boot while
+ * early_boot_irqs_disabled is set.  Use local_irq_save/restore() instead
+ * of local_irq_disable/enable().
+ */
+int on_each_cpu(void (*func) (void *info), void *info, int wait)
+{
+       unsigned long flags;
+       int ret = 0;
+
+       preempt_disable();
+       ret = smp_call_function(func, info, wait);
+       local_irq_save(flags);
+       func(info);
+       local_irq_restore(flags);
+       preempt_enable();
+       return ret;
+}
+EXPORT_SYMBOL(on_each_cpu);