linux-kernel - [PATCH] mm/hmm: fix unused variable warnings

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Message-Id: <20190304200026.1140281-1-arnd@arndb.de>
Date:   Mon,  4 Mar 2019 21:00:10 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Jérôme Glisse <jglisse@...hat.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ralph Campbell <rcampbell@...dia.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        John Hubbard <jhubbard@...dia.com>,
        Dan Williams <dan.j.williams@...el.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] mm/hmm: fix unused variable warnings

When CONFIG_HUGETLB_PAGE is disabled, the only use of the variable 'h'
is compiled out, and the compiler thinks it is unnecessary:

mm/hmm.c: In function 'hmm_range_snapshot':
mm/hmm.c:1015:19: error: unused variable 'h' [-Werror=unused-variable]
    struct hstate *h = hstate_vma(vma);

Rephrase the code to avoid the temporary variable instead, so the
compiler stops warning.

Fixes: 5409a90d4212 ("mm/hmm: support hugetlbfs (snapshotting, faulting and DMA mapping)")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 mm/hmm.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/mm/hmm.c b/mm/hmm.c
index 3c9781037918..c4beb1628cad 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -1012,9 +1012,8 @@ long hmm_range_snapshot(struct hmm_range *range)
 			return -EFAULT;
 
 		if (is_vm_hugetlb_page(vma)) {
-			struct hstate *h = hstate_vma(vma);
-
-			if (huge_page_shift(h) != range->page_shift &&
+			if (range->page_shift !=
+				huge_page_shift(hstate_vma(vma)) &&
 			    range->page_shift != PAGE_SHIFT)
 				return -EINVAL;
 		} else {
@@ -1115,9 +1114,8 @@ long hmm_range_fault(struct hmm_range *range, bool block)
 			return -EFAULT;
 
 		if (is_vm_hugetlb_page(vma)) {
-			struct hstate *h = hstate_vma(vma);
-
-			if (huge_page_shift(h) != range->page_shift &&
+			if (range->page_shift !=
+				huge_page_shift(hstate_vma(vma)) &&
 			    range->page_shift != PAGE_SHIFT)
 				return -EINVAL;
 		} else {
-- 
2.20.0