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Subject[PATCH 27/45] mm: add kernel_mbind() helper; remove in-kernel call to syscall
Date
Using the mm-internal kernel_mbind() helper allows us to get rid of the
mm-internal call to the sys_mbind() syscall.

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 <viro@zeniv.linux.org.uk>
Cc: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
---
mm/mempolicy.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 7399ede02b5f..e4d7d4c0b253 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1336,9 +1336,9 @@ static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode,
return copy_to_user(mask, nodes_addr(*nodes), copy) ? -EFAULT : 0;
}

-SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
- unsigned long, mode, const unsigned long __user *, nmask,
- unsigned long, maxnode, unsigned, flags)
+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;
@@ -1357,6 +1357,13 @@ SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
return do_mbind(start, len, mode, mode_flags, &nodes, flags);
}

+SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
+ unsigned long, mode, const unsigned long __user *, nmask,
+ unsigned long, maxnode, unsigned int, flags)
+{
+ return kernel_mbind(start, len, mode, nmask, maxnode, flags);
+}
+
/* Set the process memory policy */
SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
unsigned long, maxnode)
@@ -1575,7 +1582,7 @@ COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len,
return -EFAULT;
}

- return sys_mbind(start, len, mode, nm, nr_bits+1, flags);
+ return kernel_mbind(start, len, mode, nm, nr_bits+1, flags);
}

COMPAT_SYSCALL_DEFINE4(migrate_pages, compat_pid_t, pid,
--
2.16.2
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