[PATCH] memory hotplug locking: zone span seqlock

See the "fixup bad_range()" patch for more information, but this actually
creates a the lock to protect things making assumptions about a zone's size
staying constant at runtime.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 37 insertions, 2 deletions

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index e8103be9d528..4b08bc947578 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -16,13 +16,36 @@ void pgdat_resize_lock(struct pglist_data *pgdat, unsigned long *flags)
 static inline
 void pgdat_resize_unlock(struct pglist_data *pgdat, unsigned long *flags)
 {
-        spin_lock_irqrestore(&pgdat->node_size_lock, *flags);
+        spin_unlock_irqrestore(&pgdat->node_size_lock, *flags);
 }
 static inline
 void pgdat_resize_init(struct pglist_data *pgdat)
 {
         spin_lock_init(&pgdat->node_size_lock);
 }
+/*
+ * Zone resizing functions
+ */
+static inline unsigned zone_span_seqbegin(struct zone *zone)
+{
+        return read_seqbegin(&zone->span_seqlock);
+}
+static inline int zone_span_seqretry(struct zone *zone, unsigned iv)
+{
+        return read_seqretry(&zone->span_seqlock, iv);
+}
+static inline void zone_span_writelock(struct zone *zone)
+{
+        write_seqlock(&zone->span_seqlock);
+}
+static inline void zone_span_writeunlock(struct zone *zone)
+{
+        write_sequnlock(&zone->span_seqlock);
+}
+static inline void zone_seqlock_init(struct zone *zone)
+{
+        seqlock_init(&zone->span_seqlock);
+}
 #else /* ! CONFIG_MEMORY_HOTPLUG */
 /*
  * Stub functions for when hotplug is off
@@ -30,5 +53,17 @@ void pgdat_resize_init(struct pglist_data *pgdat)
 static inline void pgdat_resize_lock(struct pglist_data *p, unsigned long *f) {}
 static inline void pgdat_resize_unlock(struct pglist_data *p, unsigned long *f) {}
 static inline void pgdat_resize_init(struct pglist_data *pgdat) {}
-#endif
+
+static inline unsigned zone_span_seqbegin(struct zone *zone)
+{
+        return 0;
+}
+static inline int zone_span_seqretry(struct zone *zone, unsigned iv)
+{
+        return 0;
+}
+static inline void zone_span_writelock(struct zone *zone) {}
+static inline void zone_span_writeunlock(struct zone *zone) {}
+static inline void zone_seqlock_init(struct zone *zone) {}
+#endif /* ! CONFIG_MEMORY_HOTPLUG */
 #endif /* __LINUX_MEMORY_HOTPLUG_H */