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Commit d300b610 authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

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: default avatarLuis R. Rodriguez <mcgrof@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
parent 819671ff

kernel/exit.c

+1 −1
Original line number Diff line number Diff line
@@ -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

kernel/pid_namespace.c

+3 −3
Original line number Diff line number Diff line
@@ -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(),

kernel/umh.c

+2 −2
Original line number Diff line number Diff line
@@ -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