[PATCH] Fix CPU hotplug in networking

The code directly accessed the "cpucontrol" semaphore used
for CPU hotplug. That doesn't work all that well, since the
semaphore doesn't even exist on UP.

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 2f374d79f15771b002bb0a9d48a77840f1d2f4b3..02579ec6b99cfc4e92d17394e6fcd57553e95466 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -37,7 +37,12 @@ extern int register_cpu_notifier(struct notifier_block *nb);
 extern void unregister_cpu_notifier(struct notifier_block *nb);
 
 int cpu_up(unsigned int cpu);
+
+#define lock_cpu_hotplug()     down(&cpucontrol)
+#define unlock_cpu_hotplug()   up(&cpucontrol)
+
 #else
+
 static inline int register_cpu_notifier(struct notifier_block *nb)
 {
        return 0;
@@ -45,6 +50,10 @@ static inline int register_cpu_notifier(struct notifier_block *nb)
 static inline void unregister_cpu_notifier(struct notifier_block *nb)
 {
 }
+
+#define lock_cpu_hotplug()     do { } while (0)
+#define unlock_cpu_hotplug()           do { } while (0)
+
 #endif /* CONFIG_SMP */
 extern struct sysdev_class cpu_sysdev_class;
 

diff --git a/net/core/flow.c b/net/core/flow.c
index 4c920bb527078a13273f32eb38f060f331c574a1..f13a1752b6032c27a423876e10300f3a3f143ef7 100644 (file)
--- a/net/core/flow.c
+++ b/net/core/flow.c
@@ -286,7 +286,7 @@ void flow_cache_flush(void)
 
        /* Don't want cpus going down or up during this, also protects
         * against multiple callers. */
-       down(&cpucontrol);
+       lock_cpu_hotplug();
        atomic_set(&info.cpuleft, num_online_cpus());
        init_completion(&info.completion);
 
@@ -296,7 +296,7 @@ void flow_cache_flush(void)
        local_bh_enable();
 
        wait_for_completion(&info.completion);
-       up(&cpucontrol);
+       unlock_cpu_hotplug();
 }
 
 static void __devinit flow_cache_cpu_prepare(int cpu)