From 3a3814c28b13d038ce5e055fc01f9a7aa5b821b9 Mon Sep 17 00:00:00 2001
From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Date: Sat, 1 Aug 2015 18:12:41 +0200
Subject: s390/topology: remove topology lock

Since we are already protected by the "sched_domains_mutex" lock, we can
safely remove the topology lock.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c
index 0f5f8b0..1fbe1f8 100644
--- a/arch/s390/kernel/topology.c
+++ b/arch/s390/kernel/topology.c
@@ -40,8 +40,10 @@ static struct sysinfo_15_1_x *tl_info;
 static int topology_enabled = 1;
 static DECLARE_WORK(topology_work, topology_work_fn);
 
-/* topology_lock protects the socket and book linked lists */
-static DEFINE_SPINLOCK(topology_lock);
+/*
+ * Socket/Book linked lists and per_cpu(cpu_topology) updates are
+ * protected by "sched_domains_mutex".
+ */
 static struct mask_info socket_info;
 static struct mask_info book_info;
 
@@ -191,7 +193,6 @@ static void tl_to_masks(struct sysinfo_15_1_x *info)
 {
 	struct cpuid cpu_id;
 
-	spin_lock_irq(&topology_lock);
 	get_cpu_id(&cpu_id);
 	clear_masks();
 	switch (cpu_id.machine) {
@@ -202,7 +203,6 @@ static void tl_to_masks(struct sysinfo_15_1_x *info)
 	default:
 		__tl_to_masks_generic(info);
 	}
-	spin_unlock_irq(&topology_lock);
 }
 
 static void topology_update_polarization_simple(void)
@@ -247,10 +247,8 @@ int topology_set_cpu_management(int fc)
 
 static void update_cpu_masks(void)
 {
-	unsigned long flags;
 	int cpu;
 
-	spin_lock_irqsave(&topology_lock, flags);
 	for_each_possible_cpu(cpu) {
 		per_cpu(cpu_topology, cpu).thread_mask = cpu_thread_map(cpu);
 		per_cpu(cpu_topology, cpu).core_mask = cpu_group_map(&socket_info, cpu);
@@ -262,7 +260,6 @@ static void update_cpu_masks(void)
 			per_cpu(cpu_topology, cpu).book_id = cpu;
 		}
 	}
-	spin_unlock_irqrestore(&topology_lock, flags);
 	numa_update_cpu_topology();
 }
 
diff --git a/arch/s390/numa/mode_emu.c b/arch/s390/numa/mode_emu.c
index 9d4e1e1..646cd94 100644
--- a/arch/s390/numa/mode_emu.c
+++ b/arch/s390/numa/mode_emu.c
@@ -51,6 +51,11 @@ enum {TOPTREE_ID_PHYS, TOPTREE_ID_NUMA};
 static int emu_nodes = 1;
 /* NUMA stripe size */
 static unsigned long emu_size;
+
+/*
+ * Node to core pinning information updates are protected by
+ * "sched_domains_mutex".
+ */
 /* Pinned core to node mapping */
 static int cores_to_node_id[CONFIG_NR_CPUS];
 /* Total number of pinned cores */
@@ -393,7 +398,7 @@ static void print_node_to_core_map(void)
  * Transfer physical topology into a NUMA topology and modify CPU masks
  * according to the NUMA topology.
  *
- * This function is called under the CPU hotplug lock.
+ * Must be called with "sched_domains_mutex" lock held.
  */
 static void emu_update_cpu_topology(void)
 {
-- 
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