linux-kernel - [PATCH 3.18 56/68] mm/cma: silence warnings due to max() usage

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Date:   Fri,  5 May 2017 11:32:41 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Stephen Rothwell <sfr@...b.auug.org.au>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>
Subject: [PATCH 3.18 56/68] mm/cma: silence warnings due to max() usage

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stephen Rothwell <sfr@...b.auug.org.au>

commit badbda53e505089062e194c614e6f23450bc98b2 upstream.

pageblock_order can be (at least) an unsigned int or an unsigned long
depending on the kernel config and architecture, so use max_t(unsigned
long, ...) when comparing it.

fixes these warnings:

In file included from include/asm-generic/bug.h:13:0,
                 from arch/powerpc/include/asm/bug.h:127,
                 from include/linux/bug.h:4,
                 from include/linux/mmdebug.h:4,
                 from include/linux/mm.h:8,
                 from include/linux/memblock.h:18,
                 from mm/cma.c:28:
mm/cma.c: In function 'cma_init_reserved_mem':
include/linux/kernel.h:748:17: warning: comparison of distinct pointer types lacks a cast
  (void) (&_max1 == &_max2);                   ^
mm/cma.c:186:27: note: in expansion of macro 'max'
  alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
                           ^
mm/cma.c: In function 'cma_declare_contiguous':
include/linux/kernel.h:748:17: warning: comparison of distinct pointer types lacks a cast
  (void) (&_max1 == &_max2);                   ^
include/linux/kernel.h:747:9: note: in definition of macro 'max'
  typeof(y) _max2 = (y);            ^
mm/cma.c:270:29: note: in expansion of macro 'max'
   (phys_addr_t)PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order));
                             ^
include/linux/kernel.h:748:17: warning: comparison of distinct pointer types lacks a cast
  (void) (&_max1 == &_max2);                   ^
include/linux/kernel.h:747:21: note: in definition of macro 'max'
  typeof(y) _max2 = (y);                        ^
mm/cma.c:270:29: note: in expansion of macro 'max'
   (phys_addr_t)PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order));
                             ^

[akpm@...ux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20160526150748.5be38a4f@canb.auug.org.au
Signed-off-by: Stephen Rothwell <sfr@...b.auug.org.au>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 mm/cma.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/mm/cma.c
+++ b/mm/cma.c
@@ -168,7 +168,8 @@ int __init cma_init_reserved_mem(phys_ad
 		return -EINVAL;
 
 	/* ensure minimal alignment requied by mm core */
-	alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
+	alignment = PAGE_SIZE <<
+			max_t(unsigned long, MAX_ORDER - 1, pageblock_order);
 
 	/* alignment should be aligned with order_per_bit */
 	if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
@@ -250,8 +251,8 @@ int __init cma_declare_contiguous(phys_a
 	 * migratetype page by page allocator's buddy algorithm. In the case,
 	 * you couldn't get a contiguous memory, which is not what we want.
 	 */
-	alignment = max(alignment,
-		(phys_addr_t)PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order));
+	alignment = max(alignment,  (phys_addr_t)PAGE_SIZE <<
+			  max_t(unsigned long, MAX_ORDER - 1, pageblock_order));
 	base = ALIGN(base, alignment);
 	size = ALIGN(size, alignment);
 	limit &= ~(alignment - 1);