[Xen-devel] [PATCH RFCv2 5/6] powerpc/powernv: hold device_hotplug_lock in memtrace_offline_pages()

[David Hildenbrand <david@xxxxxxxxxx>]

Let's perform all checking + offlining + removing under
device_hotplug_lock, so nobody can mess with these devices via
sysfs concurrently.

Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Rashmica Gupta <rashmica.g@xxxxxxxxx>
Cc: Balbir Singh <bsingharora@xxxxxxxxx>
Cc: Michael Neuling <mikey@xxxxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
 arch/powerpc/platforms/powernv/memtrace.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/memtrace.c 
b/arch/powerpc/platforms/powernv/memtrace.c
index ef7181d4fe68..473e59842ec5 100644
--- a/arch/powerpc/platforms/powernv/memtrace.c
+++ b/arch/powerpc/platforms/powernv/memtrace.c
@@ -74,9 +74,13 @@ static bool memtrace_offline_pages(u32 nid, u64 start_pfn, 
u64 nr_pages)
 {
        u64 end_pfn = start_pfn + nr_pages - 1;
 
+       lock_device_hotplug();
+
        if (walk_memory_range(start_pfn, end_pfn, NULL,
-           check_memblock_online))
+           check_memblock_online)) {
+               unlock_device_hotplug();
                return false;
+       }
 
        walk_memory_range(start_pfn, end_pfn, (void *)MEM_GOING_OFFLINE,
                          change_memblock_state);
@@ -84,14 +88,16 @@ static bool memtrace_offline_pages(u32 nid, u64 start_pfn, 
u64 nr_pages)
        if (offline_pages(start_pfn, nr_pages)) {
                walk_memory_range(start_pfn, end_pfn, (void *)MEM_ONLINE,
                                  change_memblock_state);
+               unlock_device_hotplug();
                return false;
        }
 
        walk_memory_range(start_pfn, end_pfn, (void *)MEM_OFFLINE,
                          change_memblock_state);
 
-       remove_memory(nid, start_pfn << PAGE_SHIFT, nr_pages << PAGE_SHIFT);
+       __remove_memory(nid, start_pfn << PAGE_SHIFT, nr_pages << PAGE_SHIFT);
 
+       unlock_device_hotplug();
        return true;
 }
 
-- 
2.17.1


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