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Subject[PATCH 08/45] fs: add kern_select() helper; remove in-kernel call to sys_select()
Date
Using this helper allows us to avoid the in-kernel call to the sys_umount()
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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
---
fs/select.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/select.c b/fs/select.c
index b6c36254028a..b5df01c4587d 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -675,8 +675,8 @@ int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
return ret;
}

-SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,
- fd_set __user *, exp, struct timeval __user *, tvp)
+static int kern_select(int n, fd_set __user *inp, fd_set __user *outp,
+ fd_set __user *exp, struct timeval __user *tvp)
{
struct timespec64 end_time, *to = NULL;
struct timeval tv;
@@ -699,6 +699,12 @@ SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,
return ret;
}

+SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,
+ fd_set __user *, exp, struct timeval __user *, tvp)
+{
+ return kern_select(n, inp, outp, exp, tvp);
+}
+
static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp,
fd_set __user *exp, struct timespec __user *tsp,
const sigset_t __user *sigmask, size_t sigsetsize)
@@ -784,7 +790,7 @@ SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg)

if (copy_from_user(&a, arg, sizeof(a)))
return -EFAULT;
- return sys_select(a.n, a.inp, a.outp, a.exp, a.tvp);
+ return kern_select(a.n, a.inp, a.outp, a.exp, a.tvp);
}
#endif

--
2.16.2
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