From fef23e7fbb11a0a78cd61935f7056bc2b237995a Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Tue, 28 Mar 2006 16:10:58 -0800
Subject: [PATCH] [PATCH] exec: allow init to exec from any thread.
After looking at the problem of init calling exec some more I figured out
an easy way to make the code work.
The actual symptom without out this patch is that all threads will die
except pid == 1, and the thread calling exec. The thread calling exec will
wait forever for pid == 1 to die.
Since pid == 1 does not install a handler for SIGKILL it will never die.
This modifies the tests for init from current->pid == 1 to the equivalent
current == child_reaper. And then it causes exec in the ugly case to
modify child_reaper.
The only weird symptom is that you wind up with an init process that
doesn't have the oldest start time on the box.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
fs/exec.c | 13 ++++++++++++-
kernel/exit.c | 2 +-
kernel/signal.c | 2 +-
3 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index c7397c46ad6d..d0ecea0781f7 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -660,12 +660,23 @@ static int de_thread(struct task_struct *tsk)
struct dentry *proc_dentry1, *proc_dentry2;
unsigned long ptrace;
+ leader = current->group_leader;
+ /*
+ * If our leader is the child_reaper become
+ * the child_reaper and resend SIGKILL signal.
+ */
+ if (unlikely(leader == child_reaper)) {
+ write_lock(&tasklist_lock);
+ child_reaper = current;
+ zap_other_threads(current);
+ write_unlock(&tasklist_lock);
+ }
+
/*
* Wait for the thread group leader to be a zombie.
* It should already be zombie at this point, most
* of the time.
*/
- leader = current->group_leader;
while (leader->exit_state != EXIT_ZOMBIE)
yield();
diff --git a/kernel/exit.c b/kernel/exit.c
index a8c7efc7a681..223a8802b665 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -807,7 +807,7 @@ fastcall NORET_TYPE void do_exit(long code)
panic("Aiee, killing interrupt handler!");
if (unlikely(!tsk->pid))
panic("Attempted to kill the idle task!");
- if (unlikely(tsk->pid == 1))
+ if (unlikely(tsk == child_reaper))
panic("Attempted to kill init!");
if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
diff --git a/kernel/signal.c b/kernel/signal.c
index 75f7341b0c39..dc8f91bf9f89 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1990,7 +1990,7 @@ relock:
continue;
/* Init gets no signals it doesn't want. */
- if (current->pid == 1)
+ if (current == child_reaper)
continue;
if (sig_kernel_stop(signr)) {
--
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