From c415c3b47ea2754659d915cca387a20999044163 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 5 Mar 2012 14:59:13 -0800 Subject: vfork: introduce complete_vfork_done() No functional changes. Move the clear-and-complete-vfork_done code into the new trivial helper, complete_vfork_done(). Signed-off-by: Oleg Nesterov Acked-by: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/sched.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index 7d379a6bfd88..1b25a37f2aee 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2291,6 +2291,7 @@ 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); -- cgit v1.2.3 From d68b46fe16ad59b3a5f51ec73daaa5dc06753798 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 5 Mar 2012 14:59:13 -0800 Subject: vfork: make it killable Make vfork() killable. Change do_fork(CLONE_VFORK) to do wait_for_completion_killable(). If it fails we do not return to the user-mode and never touch the memory shared with our child. However, in this case we should clear child->vfork_done before return, we use task_lock() in do_fork()->wait_for_vfork_done() and complete_vfork_done() to serialize with each other. Note: now that we use task_lock() we don't really need completion, we could turn task->vfork_done into "task_struct *wake_up_me" but this needs some complications. NOTE: this and the next patches do not affect in-kernel users of CLONE_VFORK, kernel threads run with all signals ignored including SIGKILL/SIGSTOP. However this is obviously the user-visible change. Not only a fatal signal can kill the vforking parent, a sub-thread can do execve or exit_group() and kill the thread sleeping in vfork(). Signed-off-by: Oleg Nesterov Acked-by: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/sched.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index 1b25a37f2aee..b6467711f12e 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2372,7 +2372,7 @@ static inline int thread_group_empty(struct task_struct *p) * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring * subscriptions and synchronises with wait4(). Also used in procfs. Also * pins the final release of task.io_context. Also protects ->cpuset and - * ->cgroup.subsys[]. + * ->cgroup.subsys[]. And ->vfork_done. * * Nests both inside and outside of read_lock(&tasklist_lock). * It must not be nested with write_lock_irq(&tasklist_lock), -- cgit v1.2.3 From 57b59c4a1400fa6c34764eab2e35a8762dc05a09 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 5 Mar 2012 14:59:13 -0800 Subject: coredump_wait: don't call complete_vfork_done() 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 Acked-by: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/sched.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index b6467711f12e..11fcafaf4ae4 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2291,7 +2291,6 @@ 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); -- cgit v1.2.3 From 6e27f63edbd7ab893258e16500171dd1270a1369 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 5 Mar 2012 14:59:14 -0800 Subject: vfork: kill PF_STARTING Previously it was (ab)used by utrace. Then it was wrongly used by the scheduler code. Currently it is not used, kill it before it finds the new erroneous user. Signed-off-by: Oleg Nesterov Acked-by: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/sched.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index 11fcafaf4ae4..0657368bd78f 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1777,7 +1777,6 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t * /* * Per process flags */ -#define PF_STARTING 0x00000002 /* being created */ #define PF_EXITING 0x00000004 /* getting shut down */ #define PF_EXITPIDONE 0x00000008 /* pi exit done on shut down */ #define PF_VCPU 0x00000010 /* I'm a virtual CPU */ -- cgit v1.2.3