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Commit d47419cd authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

call_usermodehelper: simplify/fix UMH_NO_WAIT case 



__call_usermodehelper(UMH_NO_WAIT) has 2 problems:

	- if kernel_thread() fails, call_usermodehelper_freeinfo()
	  is not called.

	- for unknown reason UMH_NO_WAIT has UMH_WAIT_PROC logic,
	  we spawn yet another thread which waits until the user
	  mode application exits.

Change the UMH_NO_WAIT code to use ____call_usermodehelper() instead of
wait_for_helper(), and do call_usermodehelper_freeinfo() unconditionally.
We can rely on CLONE_VFORK, do_fork(CLONE_VFORK) until the child exits or
execs.

With or without this patch UMH_NO_WAIT does not report the error if
kernel_thread() fails, this is correct since the caller doesn't wait for
result.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7d642242

kernel/kmod.c

+4 −6
Original line number Diff line number Diff line
@@ -205,9 +205,6 @@ static int wait_for_helper(void *data) 
			sub_info->retval = ret;

	}



	if (sub_info->wait == UMH_NO_WAIT)

		call_usermodehelper_freeinfo(sub_info);

	else

	complete(sub_info->complete);

	return 0;

}
@@ -217,13 +214,13 @@ static void __call_usermodehelper(struct work_struct *work) 
{

	struct subprocess_info *sub_info =

		container_of(work, struct subprocess_info, work);

	pid_t pid;

	enum umh_wait wait = sub_info->wait;

	pid_t pid;



	/* CLONE_VFORK: wait until the usermode helper has execve'd

	 * successfully We need the data structures to stay around

	 * until that is done.  */

	if (wait == UMH_WAIT_PROC || wait == UMH_NO_WAIT)

	if (wait == UMH_WAIT_PROC)

		pid = kernel_thread(wait_for_helper, sub_info,

				    CLONE_FS | CLONE_FILES | SIGCHLD);

	else
@@ -232,6 +229,7 @@ static void __call_usermodehelper(struct work_struct *work) 


	switch (wait) {

	case UMH_NO_WAIT:

		call_usermodehelper_freeinfo(sub_info);

		break;



	case UMH_WAIT_PROC: