linux-kernel - [PATCH 1/3] mm/io-mapping: precompute remap protection flags for clarity

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Message-Id: <20250427100442.958352-2-ye.liu@linux.dev>
Date: Sun, 27 Apr 2025 18:04:40 +0800
From: Ye Liu <ye.liu@...ux.dev>
To: akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	rppt@...nel.org,
	lorenzo.stoakes@...cle.com,
	Liam.Howlett@...cle.com,
	david@...hat.com,
	harry.yoo@...cle.com,
	riel@...riel.com,
	vbabka@...e.cz,
	liuye@...inos.cn,
	ye.liu@...ux.dev
Subject: [PATCH 1/3] mm/io-mapping: precompute remap protection flags for clarity

From: Ye Liu <liuye@...inos.cn>

In io_mapping_map_user(), precompute the page protection flags in a local
variable before calling remap_pfn_range_notrack().

No functional change.

Signed-off-by: Ye Liu <liuye@...inos.cn>
---
 mm/io-mapping.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/mm/io-mapping.c b/mm/io-mapping.c
index 01b362799930..f44a6a134712 100644
--- a/mm/io-mapping.c
+++ b/mm/io-mapping.c
@@ -21,9 +21,10 @@ int io_mapping_map_user(struct io_mapping *iomap, struct vm_area_struct *vma,
 	if (WARN_ON_ONCE((vma->vm_flags & expected_flags) != expected_flags))
 		return -EINVAL;
 
+	pgprot_t remap_prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
+				       (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
+
 	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
-	return remap_pfn_range_notrack(vma, addr, pfn, size,
-		__pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
-			 (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK)));
+	return remap_pfn_range_notrack(vma, addr, pfn, size, remap_prot);
 }
 EXPORT_SYMBOL_GPL(io_mapping_map_user);
-- 
2.25.1