mm: Implement for_each_valid_pfn() for CONFIG_FLATMEM

In the FLATMEM case, the default pfn_valid() just checks that the PFN is
within the range [ ARCH_PFN_OFFSET .. ARCH_PFN_OFFSET + max_mapnr ).

The for_each_valid_pfn() function can therefore be a simple for() loop
using those as min/max respectively.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
index a3b5029aebbdc1435fbc9bbea88a2a290526877b..74d0077cc5faa9beb5efe4b134e71777aba8434b 100644 (file)
--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -30,7 +30,15 @@ static inline int pfn_valid(unsigned long pfn)
        return pfn >= pfn_offset && (pfn - pfn_offset) < max_mapnr;
 }
 #define pfn_valid pfn_valid
-#endif
+
+#ifndef for_each_valid_pfn
+#define for_each_valid_pfn(pfn, start_pfn, end_pfn)                     \
+       for ((pfn) = max_t(unsigned long, (start_pfn), ARCH_PFN_OFFSET); \
+            (pfn) < min_t(unsigned long, (end_pfn),                     \
+                          ARCH_PFN_OFFSET + max_mapnr);                 \
+            (pfn)++)
+#endif /* for_each_valid_pfn */
+#endif /* valid_pfn */
 
 #elif defined(CONFIG_SPARSEMEM_VMEMMAP)