kernel: use kernel_wait4() instead of sys_wait4()

All call sites of sys_wait4() set *rusage to NULL. Therefore, there is
no need for the copy_to_user() handling of *rusage, and we can use
kernel_wait4() directly.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Acked-by: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

diff --git a/kernel/exit.c b/kernel/exit.c
index 995453d..c3c7ac5 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1691,7 +1691,7 @@ SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
  */
 SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
 {
-       return sys_wait4(pid, stat_addr, options, NULL);
+       return kernel_wait4(pid, stat_addr, options, NULL);
 }
 
 #endif

diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 0b53eef..93b57f0 100644 (file)
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -242,16 +242,16 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
 
        /*
         * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD.
-        * sys_wait4() will also block until our children traced from the
+        * kernel_wait4() will also block until our children traced from the
         * parent namespace are detached and become EXIT_DEAD.
         */
        do {
                clear_thread_flag(TIF_SIGPENDING);
-               rc = sys_wait4(-1, NULL, __WALL, NULL);
+               rc = kernel_wait4(-1, NULL, __WALL, NULL);
        } while (rc != -ECHILD);
 
        /*
-        * sys_wait4() above can't reap the EXIT_DEAD children but we do not
+        * kernel_wait4() above can't reap the EXIT_DEAD children but we do not
         * really care, we could reparent them to the global init. We could
         * exit and reap ->child_reaper even if it is not the last thread in
         * this pid_ns, free_pid(pid_allocated == 0) calls proc_cleanup_work(),

diff --git a/kernel/umh.c b/kernel/umh.c
index 18e5fa4..f76b3ff 100644 (file)
--- a/kernel/umh.c
+++ b/kernel/umh.c
@@ -118,7 +118,7 @@ static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
 {
        pid_t pid;
 
-       /* If SIGCLD is ignored sys_wait4 won't populate the status. */
+       /* If SIGCLD is ignored kernel_wait4 won't populate the status. */
        kernel_sigaction(SIGCHLD, SIG_DFL);
        pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD);
        if (pid < 0) {
@@ -135,7 +135,7 @@ static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
                 *
                 * Thus the __user pointer cast is valid here.
                 */
-               sys_wait4(pid, (int __user *)&ret, 0, NULL);
+               kernel_wait4(pid, (int __user *)&ret, 0, NULL);
 
                /*
                 * If ret is 0, either call_usermodehelper_exec_async failed and