drm/amd/display: Add Logging for HDMI color depth information

[linux-2.6-microblaze.git] / drivers / base / arch_topology.c

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index c1179ed..921312a 100644 (file)
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -18,10 +18,11 @@
 #include <linux/cpumask.h>
 #include <linux/init.h>
 #include <linux/percpu.h>
+#include <linux/rcupdate.h>
 #include <linux/sched.h>
 #include <linux/smp.h>
 
-static DEFINE_PER_CPU(struct scale_freq_data *, sft_data);
+static DEFINE_PER_CPU(struct scale_freq_data __rcu *, sft_data);
 static struct cpumask scale_freq_counters_mask;
 static bool scale_freq_invariant;
 
@@ -66,16 +67,20 @@ void topology_set_scale_freq_source(struct scale_freq_data *data,
        if (cpumask_empty(&scale_freq_counters_mask))
                scale_freq_invariant = topology_scale_freq_invariant();
 
+       rcu_read_lock();
+
        for_each_cpu(cpu, cpus) {
-               sfd = per_cpu(sft_data, cpu);
+               sfd = rcu_dereference(*per_cpu_ptr(&sft_data, cpu));
 
                /* Use ARCH provided counters whenever possible */
                if (!sfd || sfd->source != SCALE_FREQ_SOURCE_ARCH) {
-                       per_cpu(sft_data, cpu) = data;
+                       rcu_assign_pointer(per_cpu(sft_data, cpu), data);
                        cpumask_set_cpu(cpu, &scale_freq_counters_mask);
                }
        }
 
+       rcu_read_unlock();
+
        update_scale_freq_invariant(true);
 }
 EXPORT_SYMBOL_GPL(topology_set_scale_freq_source);
@@ -86,22 +91,32 @@ void topology_clear_scale_freq_source(enum scale_freq_source source,
        struct scale_freq_data *sfd;
        int cpu;
 
+       rcu_read_lock();
+
        for_each_cpu(cpu, cpus) {
-               sfd = per_cpu(sft_data, cpu);
+               sfd = rcu_dereference(*per_cpu_ptr(&sft_data, cpu));
 
                if (sfd && sfd->source == source) {
-                       per_cpu(sft_data, cpu) = NULL;
+                       rcu_assign_pointer(per_cpu(sft_data, cpu), NULL);
                        cpumask_clear_cpu(cpu, &scale_freq_counters_mask);
                }
        }
 
+       rcu_read_unlock();
+
+       /*
+        * Make sure all references to previous sft_data are dropped to avoid
+        * use-after-free races.
+        */
+       synchronize_rcu();
+
        update_scale_freq_invariant(false);
 }
 EXPORT_SYMBOL_GPL(topology_clear_scale_freq_source);
 
 void topology_scale_freq_tick(void)
 {
-       struct scale_freq_data *sfd = *this_cpu_ptr(&sft_data);
+       struct scale_freq_data *sfd = rcu_dereference_sched(*this_cpu_ptr(&sft_data));
 
        if (sfd)
                sfd->set_freq_scale();