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: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 48daed4..ad9f2ed 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -205,10 +205,7 @@
sub_info->retval = ret;
}
- if (sub_info->wait == UMH_NO_WAIT)
- call_usermodehelper_freeinfo(sub_info);
- else
- complete(sub_info->complete);
+ complete(sub_info->complete);
return 0;
}
@@ -217,13 +214,13 @@
{
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 @@
switch (wait) {
case UMH_NO_WAIT:
+ call_usermodehelper_freeinfo(sub_info);
break;
case UMH_WAIT_PROC: