From: Oleg Nesterov <oleg@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, andi@firstfloor.org,
David Howells <dhowells@redhat.com>,
Neil Horman <nhorman@tuxdriver.com>,
Roland McGrath <roland@redhat.com>
Subject: [PATCH 5/6] call_usermodehelper: simplify/fix UMH_NO_WAIT case
Date: Mon, 15 Mar 2010 20:48:47 +0100 [thread overview]
Message-ID: <20100315194847.GF10896@redhat.com> (raw)
In-Reply-To: <20100315194609.GA10896@redhat.com>
__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>
---
kernel/kmod.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
--- 34-rc1/kernel/kmod.c~5_UMH_NO_WAIT 2010-03-15 20:28:31.000000000 +0100
+++ 34-rc1/kernel/kmod.c 2010-03-15 20:32:23.000000000 +0100
@@ -205,10 +205,7 @@ 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);
+ complete(sub_info->complete);
return 0;
}
@@ -217,13 +214,13 @@ static void __call_usermodehelper(struct
{
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
switch (wait) {
case UMH_NO_WAIT:
+ call_usermodehelper_freeinfo(sub_info);
break;
case UMH_WAIT_PROC:
next prev parent reply other threads:[~2010-03-15 19:50 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-15 12:29 [PATCH 0/2] exec: refactor how call_usermodehelper works, and update the sense of the core_pipe recursion check (v4 rediff) Neil Horman
2010-03-15 12:33 ` [PATCH 1/2] kmod: add init function to usermodehelper Neil Horman
2010-03-15 17:34 ` Oleg Nesterov
2010-03-15 17:56 ` Neil Horman
2010-03-15 12:36 ` [PATCH 2/2] exec: replace call_usermodehelper_pipe with use of umh init function and resolve limit Neil Horman
2010-03-15 17:39 ` Oleg Nesterov
2010-03-15 19:46 ` [PATCH 0/6] umh: keys, signals, misc Oleg Nesterov
2010-03-15 19:46 ` [PATCH 1/6] umh: creds: convert call_usermodehelper_keys() to use subprocess_info->init() Oleg Nesterov
2010-03-15 19:47 ` [PATCH 2/6] umh: creds: kill subprocess_info->cred logic Oleg Nesterov
2010-03-15 19:47 ` [PATCH 3/6] call_usermodehelper: no need to unblock signals Oleg Nesterov
2010-03-15 19:48 ` [PATCH 4/6] wait_for_helper: SIGCHLD from user-space can lead to use-after-free Oleg Nesterov
2010-03-15 19:48 ` Oleg Nesterov [this message]
2010-03-15 19:49 ` [PATCH 6/6] call_usermodehelper: UMH_WAIT_EXEC ignores kernel_thread() failure Oleg Nesterov
2010-03-16 19:37 ` [PATCH 0/4] do_coredump: cleanups Oleg Nesterov
2010-03-16 19:38 ` [PATCH 1/4] coredump: factor out the not-ispipe file checks Oleg Nesterov
2010-03-16 19:38 ` [PATCH 2/4] coredump: cleanup "ispipe" code Oleg Nesterov
2010-03-16 19:39 ` [PATCH 3/4] coredump: factor out put_cred() calls Oleg Nesterov
2010-03-16 19:39 ` [PATCH 4/4] coredump: shift down_write(mmap_sem) into coredump_wait() Oleg Nesterov
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