[PATCH 28/45] mm: add kernel_[sg]et_mempolicy() helpers; remove in-kernel calls to syscalls

[Dominik Brodowski]

Using the mm-internal kernel_[sg]et_mempolicy() helper allows us to get
rid of the mm-internal calls to the sys_[sg]et_mempolicy() syscalls.

This patch is part of a series which tries to remove in-kernel calls to
syscalls. On this basis, the syscall entry path can be streamlined.

Cc: Al Viro <v...@zeniv.linux.org.uk>
Cc: linux...@kvack.org
Cc: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Dominik Brodowski <li...@dominikbrodowski.net>
---
 mm/mempolicy.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index e4d7d4c0b253..ca817e768d0e 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1365,8 +1365,8 @@ SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned 
long, len,
 }
 
 /* Set the process memory policy */
-SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
-               unsigned long, maxnode)
+static long kernel_set_mempolicy(int mode, const unsigned long __user *nmask,
+                                unsigned long maxnode)
 {
        int err;
        nodemask_t nodes;
@@ -1384,6 +1384,12 @@ SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned 
long __user *, nmask,
        return do_set_mempolicy(mode, flags, &nodes);
 }
 
+SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
+               unsigned long, maxnode)
+{
+       return kernel_set_mempolicy(mode, nmask, maxnode);
+}
+
 static int kernel_migrate_pages(pid_t pid, unsigned long maxnode,
                                const unsigned long __user *old_nodes,
                                const unsigned long __user *new_nodes)
@@ -1485,9 +1491,11 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned 
long, maxnode,
 
 
 /* Retrieve NUMA policy */
-SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
-               unsigned long __user *, nmask, unsigned long, maxnode,
-               unsigned long, addr, unsigned long, flags)
+static int kernel_get_mempolicy(int __user *policy,
+                               unsigned long __user *nmask,
+                               unsigned long maxnode,
+                               unsigned long addr,
+                               unsigned long flags)
 {
        int err;
        int uninitialized_var(pval);
@@ -1510,6 +1518,13 @@ SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
        return err;
 }
 
+SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
+               unsigned long __user *, nmask, unsigned long, maxnode,
+               unsigned long, addr, unsigned long, flags)
+{
+       return kernel_get_mempolicy(policy, nmask, maxnode, addr, flags);
+}
+
 #ifdef CONFIG_COMPAT
 
 COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
@@ -1528,7 +1543,7 @@ COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, 
policy,
        if (nmask)
                nm = compat_alloc_user_space(alloc_size);
 
-       err = sys_get_mempolicy(policy, nm, nr_bits+1, addr, flags);
+       err = kernel_get_mempolicy(policy, nm, nr_bits+1, addr, flags);
 
        if (!err && nmask) {
                unsigned long copy_size;
@@ -1560,7 +1575,7 @@ COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, 
compat_ulong_t __user *, nmask,
                        return -EFAULT;
        }
 
-       return sys_set_mempolicy(mode, nm, nr_bits+1);
+       return kernel_set_mempolicy(mode, nm, nr_bits+1);
 }
 
 COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len,
-- 
2.16.2