1 files changed, 11 insertions, 65 deletions

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 2656924415da..ac222d0ab12e 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -439,9 +439,8 @@ void do_softirq(void)
 
 static LIST_HEAD(irq_hosts);
 static DEFINE_SPINLOCK(irq_big_lock);
-static DEFINE_PER_CPU(unsigned int, irq_radix_reader);
-static unsigned int irq_radix_writer;
 static unsigned int revmap_trees_allocated;
+static DEFINE_MUTEX(revmap_trees_mutex);
 struct irq_map_entry irq_map[NR_IRQS];
 static unsigned int irq_virq_count = NR_IRQS;
 static struct irq_host *irq_default_host;
@@ -584,57 +583,6 @@ void irq_set_virq_count(unsigned int count)
                 irq_virq_count = count;
 }
 
-/* radix tree not lockless safe ! we use a brlock-type mecanism
- * for now, until we can use a lockless radix tree
- */
-static void irq_radix_wrlock(unsigned long *flags)
-{
-        unsigned int cpu, ok;
-
-        spin_lock_irqsave(&irq_big_lock, *flags);
-        irq_radix_writer = 1;
-        smp_mb();
-        do {
-                barrier();
-                ok = 1;
-                for_each_possible_cpu(cpu) {
-                        if (per_cpu(irq_radix_reader, cpu)) {
-                                ok = 0;
-                                break;
-                        }
-                }
-                if (!ok)
-                        cpu_relax();
-        } while(!ok);
-}
-
-static void irq_radix_wrunlock(unsigned long flags)
-{
-        smp_wmb();
-        irq_radix_writer = 0;
-        spin_unlock_irqrestore(&irq_big_lock, flags);
-}
-
-static void irq_radix_rdlock(unsigned long *flags)
-{
-        local_irq_save(*flags);
-        __get_cpu_var(irq_radix_reader) = 1;
-        smp_mb();
-        if (likely(irq_radix_writer == 0))
-                return;
-        __get_cpu_var(irq_radix_reader) = 0;
-        smp_wmb();
-        spin_lock(&irq_big_lock);
-        __get_cpu_var(irq_radix_reader) = 1;
-        spin_unlock(&irq_big_lock);
-}
-
-static void irq_radix_rdunlock(unsigned long flags)
-{
-        __get_cpu_var(irq_radix_reader) = 0;
-        local_irq_restore(flags);
-}
-
 static int irq_setup_virq(struct irq_host *host, unsigned int virq,
                             irq_hw_number_t hwirq)
 {
@@ -789,7 +737,6 @@ void irq_dispose_mapping(unsigned int virq)
 {
         struct irq_host *host;
         irq_hw_number_t hwirq;
-        unsigned long flags;
 
         if (virq == NO_IRQ)
                 return;
@@ -829,9 +776,9 @@ void irq_dispose_mapping(unsigned int virq)
                 smp_rmb();
                 if (revmap_trees_allocated < 1)
                         break;
-                irq_radix_wrlock(&flags);
+                mutex_lock(&revmap_trees_mutex);
                 radix_tree_delete(&host->revmap_data.tree, hwirq);
-                irq_radix_wrunlock(flags);
+                mutex_unlock(&revmap_trees_mutex);
                 break;
         }
 
@@ -885,7 +832,6 @@ unsigned int irq_radix_revmap_lookup(struct irq_host *host,
 {
         struct irq_map_entry *ptr;
         unsigned int virq;
-        unsigned long flags;
 
         WARN_ON(host->revmap_type != IRQ_HOST_MAP_TREE);
 
@@ -897,9 +843,11 @@ unsigned int irq_radix_revmap_lookup(struct irq_host *host,
                 return irq_find_mapping(host, hwirq);
 
         /* Now try to resolve */
-        irq_radix_rdlock(&flags);
+        /*
+         * No rcu_read_lock(ing) needed, the ptr returned can't go under us
+         * as it's referencing an entry in the static irq_map table.
+         */
         ptr = radix_tree_lookup(&host->revmap_data.tree, hwirq);
-        irq_radix_rdunlock(flags);
 
         /*
          * If found in radix tree, then fine.
@@ -917,7 +865,6 @@ unsigned int irq_radix_revmap_lookup(struct irq_host *host,
 void irq_radix_revmap_insert(struct irq_host *host, unsigned int virq,
                              irq_hw_number_t hwirq)
 {
-        unsigned long flags;
 
         WARN_ON(host->revmap_type != IRQ_HOST_MAP_TREE);
 
@@ -931,10 +878,10 @@ void irq_radix_revmap_insert(struct irq_host *host, unsigned int virq,
                 return;
 
         if (virq != NO_IRQ) {
-                irq_radix_wrlock(&flags);
+                mutex_lock(&revmap_trees_mutex);
                 radix_tree_insert(&host->revmap_data.tree, hwirq,
                                   &irq_map[virq]);
-                irq_radix_wrunlock(flags);
+                mutex_unlock(&revmap_trees_mutex);
         }
 }
 
@@ -1044,7 +991,6 @@ void irq_early_init(void)
 static int irq_late_init(void)
 {
         struct irq_host *h;
-        unsigned long flags;
         unsigned int i;
 
         /*
@@ -1068,14 +1014,14 @@ static int irq_late_init(void)
          * Insert the reverse mapping for those interrupts already present
          * in irq_map[].
          */
-        irq_radix_wrlock(&flags);
+        mutex_lock(&revmap_trees_mutex);
         for (i = 0; i < irq_virq_count; i++) {
                 if (irq_map[i].host &&
                     (irq_map[i].host->revmap_type == IRQ_HOST_MAP_TREE))
                         radix_tree_insert(&irq_map[i].host->revmap_data.tree,
                                           irq_map[i].hwirq, &irq_map[i]);
         }
-        irq_radix_wrunlock(flags);
+        mutex_unlock(&revmap_trees_mutex);
 
         /*
          * Make sure the radix trees insertions are visible before setting