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Subject[PATCH RFCv2 5/6] powerpc/powernv: hold device_hotplug_lock in memtrace_offline_pages()
Date
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@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Rashmica Gupta <rashmica.g@gmail.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Michael Neuling <mikey@neuling.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
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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