mm/percpu.c: introduce pcpu_alloc_size()

[linux-block.git] / mm / percpu.c

diff --git a/mm/percpu.c b/mm/percpu.c
index ea607078368df047411b79d95e8b63b80ceac23e..60ed078e4cd06ae59e90f4a29f04dc4008d51234 100644 (file)
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -2244,6 +2244,37 @@ static void pcpu_balance_workfn(struct work_struct *work)
        mutex_unlock(&pcpu_alloc_mutex);
 }
 
+/**
+ * pcpu_alloc_size - the size of the dynamic percpu area
+ * @ptr: pointer to the dynamic percpu area
+ *
+ * Returns the size of the @ptr allocation.  This is undefined for statically
+ * defined percpu variables as there is no corresponding chunk->bound_map.
+ *
+ * RETURNS:
+ * The size of the dynamic percpu area.
+ *
+ * CONTEXT:
+ * Can be called from atomic context.
+ */
+size_t pcpu_alloc_size(void __percpu *ptr)
+{
+       struct pcpu_chunk *chunk;
+       unsigned long bit_off, end;
+       void *addr;
+
+       if (!ptr)
+               return 0;
+
+       addr = __pcpu_ptr_to_addr(ptr);
+       /* No pcpu_lock here: ptr has not been freed, so chunk is still alive */
+       chunk = pcpu_chunk_addr_search(addr);
+       bit_off = (addr - chunk->base_addr) / PCPU_MIN_ALLOC_SIZE;
+       end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk),
+                           bit_off + 1);
+       return (end - bit_off) * PCPU_MIN_ALLOC_SIZE;
+}
+
 /**
  * free_percpu - free percpu area
  * @ptr: pointer to area to free