[PATCH 4/8] coredump_wait: don't call complete_vfork_done()

Oleg Nesterov
2011-07-27T16:36:21Z

Now that CLONE_VFORK is killable, coredump_wait() no longer needs
complete_vfork_done(). zap_threads() should find and kill all tasks
with the same ->mm, this includes our parent if ->vfork_done is set.

mm_release() becomes the only caller, unexport complete_vfork_done().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---

include/linux/sched.h | 1 -
fs/exec.c | 7 -------
kernel/fork.c | 3 ++-
3 files changed, 2 insertions(+), 9 deletions(-)

--- 3.1/include/linux/sched.h~4_coredump_no_vfork_done 2011-07-26 20:23:28.000000000 +0200
+++ 3.1/include/linux/sched.h 2011-07-26 20:28:24.000000000 +0200
@@ -2253,7 +2253,6 @@ extern int do_execve(const char *,
const char __user * const __user *,
const char __user * const __user *, struct pt_regs *);
extern long do_fork(unsigned long, unsigned long, struct pt_regs *, unsigned long, int __user *, int __user *);
-extern void complete_vfork_done(struct task_struct *tsk);
struct task_struct *fork_idle(int);

extern void set_task_comm(struct task_struct *tsk, char *from);
--- 3.1/fs/exec.c~4_coredump_no_vfork_done 2011-07-26 20:23:28.000000000 +0200
+++ 3.1/fs/exec.c 2011-07-26 20:28:24.000000000 +0200
@@ -1899,13 +1899,6 @@ static int coredump_wait(int exit_code,
if (unlikely(core_waiters < 0))
goto fail;

- /*
- * Make sure nobody is waiting for us to release the VM,
- * otherwise we can deadlock when we wait on each other
- */
- if (tsk->vfork_done)
- complete_vfork_done(tsk);
-
if (core_waiters)
wait_for_completion(&core_state->startup);
fail:
--- 3.1/kernel/fork.c~4_coredump_no_vfork_done 2011-07-26 20:23:28.000000000 +0200
+++ 3.1/kernel/fork.c 2011-07-26 20:28:24.000000000 +0200
@@ -647,6 +647,7 @@ struct mm_struct *get_task_mm(struct tas
}
EXPORT_SYMBOL_GPL(get_task_mm);

+static void complete_vfork_done(struct task_struct *tsk);
/* Please note the differences between mmput and mm_release.
* mmput is called whenever we stop holding onto a mm_struct,
* error success whatever.
@@ -1442,7 +1443,7 @@ struct task_struct * __cpuinit fork_idle
return task;
}

-void complete_vfork_done(struct task_struct *tsk)
+static void complete_vfork_done(struct task_struct *tsk)
{
struct completion *vfork_done = xchg(&tsk->vfork_done, NULL);