linux-kernel - [RFC Patch v2 2/4] mm/mempolicy: unify the preprocessing for mbind and set

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Date:   Thu, 20 May 2021 16:30:02 +0800
From:   Feng Tang <feng.tang@...el.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>
Cc:     Andrea Arcangeli <aarcange@...hat.com>,
        David Rientjes <rientjes@...gle.com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Dave Hansen <dave.hansen@...el.com>,
        Ben Widawsky <ben.widawsky@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Dan Williams <dan.j.williams@...el.com>, ying.huang@...el.com,
        Feng Tang <feng.tang@...el.com>
Subject: [RFC Patch v2 2/4] mm/mempolicy: unify the preprocessing for mbind and set_mempolicy

Currently the kernel_mbind() and kernel_set_mempolicy() do almost
the same operation for parameter sanity check and preprocessing.

Add a macro to unify the code to reduce the redundancy, and make
it easier for changing the pre-processing code in future.

Signed-off-by: Feng Tang <feng.tang@...el.com>
---
 mm/mempolicy.c | 46 +++++++++++++++++++---------------------------
 1 file changed, 19 insertions(+), 27 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 1964cca..0f5bf60 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1460,25 +1460,29 @@ static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode,
 	return copy_to_user(mask, nodes_addr(*nodes), copy) ? -EFAULT : 0;
 }
 
+#define MPOL_PRE_PROCESS() \
+	 \
+	nodemask_t nodes; \
+	int err; \
+	unsigned short mode_flags; \
+	mode_flags = mode & MPOL_MODE_FLAGS; \
+	mode &= ~MPOL_MODE_FLAGS; \
+	if (mode >= MPOL_MAX) \
+		return -EINVAL; \
+	if ((mode_flags & MPOL_F_STATIC_NODES) && \
+		(mode_flags & MPOL_F_RELATIVE_NODES)) \
+		return -EINVAL; \
+	err = get_nodes(&nodes, nmask, maxnode); \
+	if (err) \
+		return err;
+
 static long kernel_mbind(unsigned long start, unsigned long len,
 			 unsigned long mode, const unsigned long __user *nmask,
 			 unsigned long maxnode, unsigned int flags)
 {
-	nodemask_t nodes;
-	int err;
-	unsigned short mode_flags;
+	MPOL_PRE_PROCESS();
 
 	start = untagged_addr(start);
-	mode_flags = mode & MPOL_MODE_FLAGS;
-	mode &= ~MPOL_MODE_FLAGS;
-	if (mode >= MPOL_MAX)
-		return -EINVAL;
-	if ((mode_flags & MPOL_F_STATIC_NODES) &&
-	    (mode_flags & MPOL_F_RELATIVE_NODES))
-		return -EINVAL;
-	err = get_nodes(&nodes, nmask, maxnode);
-	if (err)
-		return err;
 	return do_mbind(start, len, mode, mode_flags, &nodes, flags);
 }
 
@@ -1493,20 +1497,8 @@ SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
 static long kernel_set_mempolicy(int mode, const unsigned long __user *nmask,
 				 unsigned long maxnode)
 {
-	int err;
-	nodemask_t nodes;
-	unsigned short flags;
-
-	flags = mode & MPOL_MODE_FLAGS;
-	mode &= ~MPOL_MODE_FLAGS;
-	if ((unsigned int)mode >= MPOL_MAX)
-		return -EINVAL;
-	if ((flags & MPOL_F_STATIC_NODES) && (flags & MPOL_F_RELATIVE_NODES))
-		return -EINVAL;
-	err = get_nodes(&nodes, nmask, maxnode);
-	if (err)
-		return err;
-	return do_set_mempolicy(mode, flags, &nodes);
+	MPOL_PRE_PROCESS();
+	return do_set_mempolicy(mode, mode_flags, &nodes);
 }
 
 SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
-- 
2.7.4