Re: [PATCH] mm,memory_hotplug: Drop unneeded locking

From: David Hildenbrand
Date: Tue Jun 01 2021 - 04:03:01 EST


On 01.06.21 09:47, Oscar Salvador wrote:
On Tue, Jun 01, 2021 at 10:47:31AM +0530, Anshuman Khandual wrote:
Should also just drop zone_span_write[lock|unlock]() helpers as there
are no users left ?

Yes, definitely.
Andrew, can you squash this on top? Thanks:

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index a7fd2c3ccb77..27d8ba1d32cb 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -67,10 +67,6 @@ struct range mhp_get_pluggable_range(bool need_mapping);
/*
* Zone resizing functions
- *
- * Note: any attempt to resize a zone should has pgdat_resize_lock()
- * zone_span_writelock() both held. This ensure the size of a zone
- * can't be changed while pgdat_resize_lock() held.
*/
static inline unsigned zone_span_seqbegin(struct zone *zone)
{
@@ -80,14 +76,6 @@ 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);
-}

If there is no writer anymore, why do we have to protect readers?



--
Thanks,

David / dhildenb