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1787 lines
46 KiB
1787 lines
46 KiB
/* |
|
* linux/kernel/exit.c |
|
* |
|
* Copyright (C) 1991, 1992 Linus Torvalds |
|
*/ |
|
|
|
#include <linux/mm.h> |
|
#include <linux/slab.h> |
|
#include <linux/interrupt.h> |
|
#include <linux/module.h> |
|
#include <linux/capability.h> |
|
#include <linux/completion.h> |
|
#include <linux/personality.h> |
|
#include <linux/tty.h> |
|
#include <linux/iocontext.h> |
|
#include <linux/key.h> |
|
#include <linux/security.h> |
|
#include <linux/cpu.h> |
|
#include <linux/acct.h> |
|
#include <linux/tsacct_kern.h> |
|
#include <linux/file.h> |
|
#include <linux/fdtable.h> |
|
#include <linux/binfmts.h> |
|
#include <linux/nsproxy.h> |
|
#include <linux/pid_namespace.h> |
|
#include <linux/ptrace.h> |
|
#include <linux/profile.h> |
|
#include <linux/mount.h> |
|
#include <linux/proc_fs.h> |
|
#include <linux/kthread.h> |
|
#include <linux/mempolicy.h> |
|
#include <linux/taskstats_kern.h> |
|
#include <linux/delayacct.h> |
|
#include <linux/freezer.h> |
|
#include <linux/cgroup.h> |
|
#include <linux/syscalls.h> |
|
#include <linux/signal.h> |
|
#include <linux/posix-timers.h> |
|
#include <linux/cn_proc.h> |
|
#include <linux/mutex.h> |
|
#include <linux/futex.h> |
|
#include <linux/pipe_fs_i.h> |
|
#include <linux/audit.h> /* for audit_free() */ |
|
#include <linux/resource.h> |
|
#include <linux/blkdev.h> |
|
#include <linux/task_io_accounting_ops.h> |
|
#include <linux/tracehook.h> |
|
#include <linux/fs_struct.h> |
|
#include <linux/init_task.h> |
|
#include <linux/perf_event.h> |
|
#include <trace/events/sched.h> |
|
#include <linux/hw_breakpoint.h> |
|
#include <linux/oom.h> |
|
#include <linux/writeback.h> |
|
#include <linux/shm.h> |
|
|
|
#include <asm/uaccess.h> |
|
#include <asm/unistd.h> |
|
#include <asm/pgtable.h> |
|
#include <asm/mmu_context.h> |
|
|
|
static void exit_mm(struct task_struct * tsk); |
|
|
|
static void __unhash_process(struct task_struct *p, bool group_dead) |
|
{ |
|
nr_threads--; |
|
detach_pid(p, PIDTYPE_PID); |
|
if (group_dead) { |
|
detach_pid(p, PIDTYPE_PGID); |
|
detach_pid(p, PIDTYPE_SID); |
|
|
|
list_del_rcu(&p->tasks); |
|
list_del_init(&p->sibling); |
|
__this_cpu_dec(process_counts); |
|
/* |
|
* If we are the last child process in a pid namespace to be |
|
* reaped, notify the reaper sleeping zap_pid_ns_processes(). |
|
*/ |
|
if (IS_ENABLED(CONFIG_PID_NS)) { |
|
struct task_struct *parent = p->real_parent; |
|
|
|
if ((task_active_pid_ns(parent)->child_reaper == parent) && |
|
list_empty(&parent->children) && |
|
(parent->flags & PF_EXITING)) |
|
wake_up_process(parent); |
|
} |
|
} |
|
list_del_rcu(&p->thread_group); |
|
} |
|
|
|
/* |
|
* This function expects the tasklist_lock write-locked. |
|
*/ |
|
static void __exit_signal(struct task_struct *tsk) |
|
{ |
|
struct signal_struct *sig = tsk->signal; |
|
bool group_dead = thread_group_leader(tsk); |
|
struct sighand_struct *sighand; |
|
struct tty_struct *uninitialized_var(tty); |
|
|
|
sighand = rcu_dereference_check(tsk->sighand, |
|
lockdep_tasklist_lock_is_held()); |
|
spin_lock(&sighand->siglock); |
|
|
|
posix_cpu_timers_exit(tsk); |
|
if (group_dead) { |
|
posix_cpu_timers_exit_group(tsk); |
|
tty = sig->tty; |
|
sig->tty = NULL; |
|
} else { |
|
/* |
|
* This can only happen if the caller is de_thread(). |
|
* FIXME: this is the temporary hack, we should teach |
|
* posix-cpu-timers to handle this case correctly. |
|
*/ |
|
if (unlikely(has_group_leader_pid(tsk))) |
|
posix_cpu_timers_exit_group(tsk); |
|
|
|
/* |
|
* If there is any task waiting for the group exit |
|
* then notify it: |
|
*/ |
|
if (sig->notify_count > 0 && !--sig->notify_count) |
|
wake_up_process(sig->group_exit_task); |
|
|
|
if (tsk == sig->curr_target) |
|
sig->curr_target = next_thread(tsk); |
|
/* |
|
* Accumulate here the counters for all threads but the |
|
* group leader as they die, so they can be added into |
|
* the process-wide totals when those are taken. |
|
* The group leader stays around as a zombie as long |
|
* as there are other threads. When it gets reaped, |
|
* the exit.c code will add its counts into these totals. |
|
* We won't ever get here for the group leader, since it |
|
* will have been the last reference on the signal_struct. |
|
*/ |
|
sig->utime += tsk->utime; |
|
sig->stime += tsk->stime; |
|
sig->gtime += tsk->gtime; |
|
sig->min_flt += tsk->min_flt; |
|
sig->maj_flt += tsk->maj_flt; |
|
sig->nvcsw += tsk->nvcsw; |
|
sig->nivcsw += tsk->nivcsw; |
|
sig->inblock += task_io_get_inblock(tsk); |
|
sig->oublock += task_io_get_oublock(tsk); |
|
task_io_accounting_add(&sig->ioac, &tsk->ioac); |
|
sig->sum_sched_runtime += tsk->se.sum_exec_runtime; |
|
} |
|
|
|
sig->nr_threads--; |
|
__unhash_process(tsk, group_dead); |
|
|
|
/* |
|
* Do this under ->siglock, we can race with another thread |
|
* doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. |
|
*/ |
|
flush_sigqueue(&tsk->pending); |
|
tsk->sighand = NULL; |
|
spin_unlock(&sighand->siglock); |
|
|
|
__cleanup_sighand(sighand); |
|
clear_tsk_thread_flag(tsk,TIF_SIGPENDING); |
|
if (group_dead) { |
|
flush_sigqueue(&sig->shared_pending); |
|
tty_kref_put(tty); |
|
} |
|
} |
|
|
|
static void delayed_put_task_struct(struct rcu_head *rhp) |
|
{ |
|
struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); |
|
|
|
perf_event_delayed_put(tsk); |
|
trace_sched_process_free(tsk); |
|
put_task_struct(tsk); |
|
} |
|
|
|
|
|
void release_task(struct task_struct * p) |
|
{ |
|
struct task_struct *leader; |
|
int zap_leader; |
|
repeat: |
|
/* don't need to get the RCU readlock here - the process is dead and |
|
* can't be modifying its own credentials. But shut RCU-lockdep up */ |
|
rcu_read_lock(); |
|
atomic_dec(&__task_cred(p)->user->processes); |
|
rcu_read_unlock(); |
|
|
|
proc_flush_task(p); |
|
|
|
write_lock_irq(&tasklist_lock); |
|
ptrace_release_task(p); |
|
__exit_signal(p); |
|
|
|
/* |
|
* If we are the last non-leader member of the thread |
|
* group, and the leader is zombie, then notify the |
|
* group leader's parent process. (if it wants notification.) |
|
*/ |
|
zap_leader = 0; |
|
leader = p->group_leader; |
|
if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { |
|
/* |
|
* If we were the last child thread and the leader has |
|
* exited already, and the leader's parent ignores SIGCHLD, |
|
* then we are the one who should release the leader. |
|
*/ |
|
zap_leader = do_notify_parent(leader, leader->exit_signal); |
|
if (zap_leader) |
|
leader->exit_state = EXIT_DEAD; |
|
} |
|
|
|
write_unlock_irq(&tasklist_lock); |
|
release_thread(p); |
|
call_rcu(&p->rcu, delayed_put_task_struct); |
|
|
|
p = leader; |
|
if (unlikely(zap_leader)) |
|
goto repeat; |
|
} |
|
|
|
/* |
|
* This checks not only the pgrp, but falls back on the pid if no |
|
* satisfactory pgrp is found. I dunno - gdb doesn't work correctly |
|
* without this... |
|
* |
|
* The caller must hold rcu lock or the tasklist lock. |
|
*/ |
|
struct pid *session_of_pgrp(struct pid *pgrp) |
|
{ |
|
struct task_struct *p; |
|
struct pid *sid = NULL; |
|
|
|
p = pid_task(pgrp, PIDTYPE_PGID); |
|
if (p == NULL) |
|
p = pid_task(pgrp, PIDTYPE_PID); |
|
if (p != NULL) |
|
sid = task_session(p); |
|
|
|
return sid; |
|
} |
|
|
|
/* |
|
* Determine if a process group is "orphaned", according to the POSIX |
|
* definition in 2.2.2.52. Orphaned process groups are not to be affected |
|
* by terminal-generated stop signals. Newly orphaned process groups are |
|
* to receive a SIGHUP and a SIGCONT. |
|
* |
|
* "I ask you, have you ever known what it is to be an orphan?" |
|
*/ |
|
static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task) |
|
{ |
|
struct task_struct *p; |
|
|
|
do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
|
if ((p == ignored_task) || |
|
(p->exit_state && thread_group_empty(p)) || |
|
is_global_init(p->real_parent)) |
|
continue; |
|
|
|
if (task_pgrp(p->real_parent) != pgrp && |
|
task_session(p->real_parent) == task_session(p)) |
|
return 0; |
|
} while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
|
|
|
return 1; |
|
} |
|
|
|
int is_current_pgrp_orphaned(void) |
|
{ |
|
int retval; |
|
|
|
read_lock(&tasklist_lock); |
|
retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); |
|
read_unlock(&tasklist_lock); |
|
|
|
return retval; |
|
} |
|
|
|
static bool has_stopped_jobs(struct pid *pgrp) |
|
{ |
|
struct task_struct *p; |
|
|
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do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
|
if (p->signal->flags & SIGNAL_STOP_STOPPED) |
|
return true; |
|
} while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
|
|
|
return false; |
|
} |
|
|
|
/* |
|
* Check to see if any process groups have become orphaned as |
|
* a result of our exiting, and if they have any stopped jobs, |
|
* send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
|
*/ |
|
static void |
|
kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) |
|
{ |
|
struct pid *pgrp = task_pgrp(tsk); |
|
struct task_struct *ignored_task = tsk; |
|
|
|
if (!parent) |
|
/* exit: our father is in a different pgrp than |
|
* we are and we were the only connection outside. |
|
*/ |
|
parent = tsk->real_parent; |
|
else |
|
/* reparent: our child is in a different pgrp than |
|
* we are, and it was the only connection outside. |
|
*/ |
|
ignored_task = NULL; |
|
|
|
if (task_pgrp(parent) != pgrp && |
|
task_session(parent) == task_session(tsk) && |
|
will_become_orphaned_pgrp(pgrp, ignored_task) && |
|
has_stopped_jobs(pgrp)) { |
|
__kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); |
|
__kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); |
|
} |
|
} |
|
|
|
/** |
|
* reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd |
|
* |
|
* If a kernel thread is launched as a result of a system call, or if |
|
* it ever exits, it should generally reparent itself to kthreadd so it |
|
* isn't in the way of other processes and is correctly cleaned up on exit. |
|
* |
|
* The various task state such as scheduling policy and priority may have |
|
* been inherited from a user process, so we reset them to sane values here. |
|
* |
|
* NOTE that reparent_to_kthreadd() gives the caller full capabilities. |
|
*/ |
|
static void reparent_to_kthreadd(void) |
|
{ |
|
write_lock_irq(&tasklist_lock); |
|
|
|
ptrace_unlink(current); |
|
/* Reparent to init */ |
|
current->real_parent = current->parent = kthreadd_task; |
|
list_move_tail(¤t->sibling, ¤t->real_parent->children); |
|
|
|
/* Set the exit signal to SIGCHLD so we signal init on exit */ |
|
current->exit_signal = SIGCHLD; |
|
|
|
if (task_nice(current) < 0) |
|
set_user_nice(current, 0); |
|
/* cpus_allowed? */ |
|
/* rt_priority? */ |
|
/* signals? */ |
|
memcpy(current->signal->rlim, init_task.signal->rlim, |
|
sizeof(current->signal->rlim)); |
|
|
|
atomic_inc(&init_cred.usage); |
|
commit_creds(&init_cred); |
|
write_unlock_irq(&tasklist_lock); |
|
} |
|
|
|
void __set_special_pids(struct pid *pid) |
|
{ |
|
struct task_struct *curr = current->group_leader; |
|
|
|
if (task_session(curr) != pid) |
|
change_pid(curr, PIDTYPE_SID, pid); |
|
|
|
if (task_pgrp(curr) != pid) |
|
change_pid(curr, PIDTYPE_PGID, pid); |
|
} |
|
|
|
static void set_special_pids(struct pid *pid) |
|
{ |
|
write_lock_irq(&tasklist_lock); |
|
__set_special_pids(pid); |
|
write_unlock_irq(&tasklist_lock); |
|
} |
|
|
|
/* |
|
* Let kernel threads use this to say that they allow a certain signal. |
|
* Must not be used if kthread was cloned with CLONE_SIGHAND. |
|
*/ |
|
int allow_signal(int sig) |
|
{ |
|
if (!valid_signal(sig) || sig < 1) |
|
return -EINVAL; |
|
|
|
spin_lock_irq(¤t->sighand->siglock); |
|
/* This is only needed for daemonize()'ed kthreads */ |
|
sigdelset(¤t->blocked, sig); |
|
/* |
|
* Kernel threads handle their own signals. Let the signal code |
|
* know it'll be handled, so that they don't get converted to |
|
* SIGKILL or just silently dropped. |
|
*/ |
|
current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2; |
|
recalc_sigpending(); |
|
spin_unlock_irq(¤t->sighand->siglock); |
|
return 0; |
|
} |
|
|
|
EXPORT_SYMBOL(allow_signal); |
|
|
|
int disallow_signal(int sig) |
|
{ |
|
if (!valid_signal(sig) || sig < 1) |
|
return -EINVAL; |
|
|
|
spin_lock_irq(¤t->sighand->siglock); |
|
current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN; |
|
recalc_sigpending(); |
|
spin_unlock_irq(¤t->sighand->siglock); |
|
return 0; |
|
} |
|
|
|
EXPORT_SYMBOL(disallow_signal); |
|
|
|
/* |
|
* Put all the gunge required to become a kernel thread without |
|
* attached user resources in one place where it belongs. |
|
*/ |
|
|
|
void daemonize(const char *name, ...) |
|
{ |
|
va_list args; |
|
sigset_t blocked; |
|
|
|
va_start(args, name); |
|
vsnprintf(current->comm, sizeof(current->comm), name, args); |
|
va_end(args); |
|
|
|
/* |
|
* If we were started as result of loading a module, close all of the |
|
* user space pages. We don't need them, and if we didn't close them |
|
* they would be locked into memory. |
|
*/ |
|
exit_mm(current); |
|
/* |
|
* We don't want to get frozen, in case system-wide hibernation |
|
* or suspend transition begins right now. |
|
*/ |
|
current->flags |= (PF_NOFREEZE | PF_KTHREAD); |
|
|
|
if (current->nsproxy != &init_nsproxy) { |
|
get_nsproxy(&init_nsproxy); |
|
switch_task_namespaces(current, &init_nsproxy); |
|
} |
|
set_special_pids(&init_struct_pid); |
|
proc_clear_tty(current); |
|
|
|
/* Block and flush all signals */ |
|
sigfillset(&blocked); |
|
sigprocmask(SIG_BLOCK, &blocked, NULL); |
|
flush_signals(current); |
|
|
|
/* Become as one with the init task */ |
|
|
|
daemonize_fs_struct(); |
|
daemonize_descriptors(); |
|
|
|
reparent_to_kthreadd(); |
|
} |
|
|
|
EXPORT_SYMBOL(daemonize); |
|
|
|
#ifdef CONFIG_MM_OWNER |
|
/* |
|
* A task is exiting. If it owned this mm, find a new owner for the mm. |
|
*/ |
|
void mm_update_next_owner(struct mm_struct *mm) |
|
{ |
|
struct task_struct *c, *g, *p = current; |
|
|
|
retry: |
|
/* |
|
* If the exiting or execing task is not the owner, it's |
|
* someone else's problem. |
|
*/ |
|
if (mm->owner != p) |
|
return; |
|
/* |
|
* The current owner is exiting/execing and there are no other |
|
* candidates. Do not leave the mm pointing to a possibly |
|
* freed task structure. |
|
*/ |
|
if (atomic_read(&mm->mm_users) <= 1) { |
|
mm->owner = NULL; |
|
return; |
|
} |
|
|
|
read_lock(&tasklist_lock); |
|
/* |
|
* Search in the children |
|
*/ |
|
list_for_each_entry(c, &p->children, sibling) { |
|
if (c->mm == mm) |
|
goto assign_new_owner; |
|
} |
|
|
|
/* |
|
* Search in the siblings |
|
*/ |
|
list_for_each_entry(c, &p->real_parent->children, sibling) { |
|
if (c->mm == mm) |
|
goto assign_new_owner; |
|
} |
|
|
|
/* |
|
* Search through everything else. We should not get |
|
* here often |
|
*/ |
|
do_each_thread(g, c) { |
|
if (c->mm == mm) |
|
goto assign_new_owner; |
|
} while_each_thread(g, c); |
|
|
|
read_unlock(&tasklist_lock); |
|
/* |
|
* We found no owner yet mm_users > 1: this implies that we are |
|
* most likely racing with swapoff (try_to_unuse()) or /proc or |
|
* ptrace or page migration (get_task_mm()). Mark owner as NULL. |
|
*/ |
|
mm->owner = NULL; |
|
return; |
|
|
|
assign_new_owner: |
|
BUG_ON(c == p); |
|
get_task_struct(c); |
|
/* |
|
* The task_lock protects c->mm from changing. |
|
* We always want mm->owner->mm == mm |
|
*/ |
|
task_lock(c); |
|
/* |
|
* Delay read_unlock() till we have the task_lock() |
|
* to ensure that c does not slip away underneath us |
|
*/ |
|
read_unlock(&tasklist_lock); |
|
if (c->mm != mm) { |
|
task_unlock(c); |
|
put_task_struct(c); |
|
goto retry; |
|
} |
|
mm->owner = c; |
|
task_unlock(c); |
|
put_task_struct(c); |
|
} |
|
#endif /* CONFIG_MM_OWNER */ |
|
|
|
/* |
|
* Turn us into a lazy TLB process if we |
|
* aren't already.. |
|
*/ |
|
static void exit_mm(struct task_struct * tsk) |
|
{ |
|
struct mm_struct *mm = tsk->mm; |
|
struct core_state *core_state; |
|
|
|
mm_release(tsk, mm); |
|
if (!mm) |
|
return; |
|
sync_mm_rss(mm); |
|
/* |
|
* Serialize with any possible pending coredump. |
|
* We must hold mmap_sem around checking core_state |
|
* and clearing tsk->mm. The core-inducing thread |
|
* will increment ->nr_threads for each thread in the |
|
* group with ->mm != NULL. |
|
*/ |
|
down_read(&mm->mmap_sem); |
|
core_state = mm->core_state; |
|
if (core_state) { |
|
struct core_thread self; |
|
up_read(&mm->mmap_sem); |
|
|
|
self.task = tsk; |
|
self.next = xchg(&core_state->dumper.next, &self); |
|
/* |
|
* Implies mb(), the result of xchg() must be visible |
|
* to core_state->dumper. |
|
*/ |
|
if (atomic_dec_and_test(&core_state->nr_threads)) |
|
complete(&core_state->startup); |
|
|
|
for (;;) { |
|
set_task_state(tsk, TASK_UNINTERRUPTIBLE); |
|
if (!self.task) /* see coredump_finish() */ |
|
break; |
|
schedule(); |
|
} |
|
__set_task_state(tsk, TASK_RUNNING); |
|
down_read(&mm->mmap_sem); |
|
} |
|
atomic_inc(&mm->mm_count); |
|
BUG_ON(mm != tsk->active_mm); |
|
/* more a memory barrier than a real lock */ |
|
task_lock(tsk); |
|
tsk->mm = NULL; |
|
up_read(&mm->mmap_sem); |
|
enter_lazy_tlb(mm, current); |
|
task_unlock(tsk); |
|
mm_update_next_owner(mm); |
|
mmput(mm); |
|
} |
|
|
|
/* |
|
* When we die, we re-parent all our children, and try to: |
|
* 1. give them to another thread in our thread group, if such a member exists |
|
* 2. give it to the first ancestor process which prctl'd itself as a |
|
* child_subreaper for its children (like a service manager) |
|
* 3. give it to the init process (PID 1) in our pid namespace |
|
*/ |
|
static struct task_struct *find_new_reaper(struct task_struct *father) |
|
__releases(&tasklist_lock) |
|
__acquires(&tasklist_lock) |
|
{ |
|
struct pid_namespace *pid_ns = task_active_pid_ns(father); |
|
struct task_struct *thread; |
|
|
|
thread = father; |
|
while_each_thread(father, thread) { |
|
if (thread->flags & PF_EXITING) |
|
continue; |
|
if (unlikely(pid_ns->child_reaper == father)) |
|
pid_ns->child_reaper = thread; |
|
return thread; |
|
} |
|
|
|
if (unlikely(pid_ns->child_reaper == father)) { |
|
write_unlock_irq(&tasklist_lock); |
|
if (unlikely(pid_ns == &init_pid_ns)) { |
|
panic("Attempted to kill init! exitcode=0x%08x\n", |
|
father->signal->group_exit_code ?: |
|
father->exit_code); |
|
} |
|
|
|
zap_pid_ns_processes(pid_ns); |
|
write_lock_irq(&tasklist_lock); |
|
} else if (father->signal->has_child_subreaper) { |
|
struct task_struct *reaper; |
|
|
|
/* |
|
* Find the first ancestor marked as child_subreaper. |
|
* Note that the code below checks same_thread_group(reaper, |
|
* pid_ns->child_reaper). This is what we need to DTRT in a |
|
* PID namespace. However we still need the check above, see |
|
* http://marc.info/?l=linux-kernel&m=131385460420380 |
|
*/ |
|
for (reaper = father->real_parent; |
|
reaper != &init_task; |
|
reaper = reaper->real_parent) { |
|
if (same_thread_group(reaper, pid_ns->child_reaper)) |
|
break; |
|
if (!reaper->signal->is_child_subreaper) |
|
continue; |
|
thread = reaper; |
|
do { |
|
if (!(thread->flags & PF_EXITING)) |
|
return reaper; |
|
} while_each_thread(reaper, thread); |
|
} |
|
} |
|
|
|
return pid_ns->child_reaper; |
|
} |
|
|
|
/* |
|
* Any that need to be release_task'd are put on the @dead list. |
|
*/ |
|
static void reparent_leader(struct task_struct *father, struct task_struct *p, |
|
struct list_head *dead) |
|
{ |
|
list_move_tail(&p->sibling, &p->real_parent->children); |
|
|
|
if (p->exit_state == EXIT_DEAD) |
|
return; |
|
/* |
|
* If this is a threaded reparent there is no need to |
|
* notify anyone anything has happened. |
|
*/ |
|
if (same_thread_group(p->real_parent, father)) |
|
return; |
|
|
|
/* We don't want people slaying init. */ |
|
p->exit_signal = SIGCHLD; |
|
|
|
/* If it has exited notify the new parent about this child's death. */ |
|
if (!p->ptrace && |
|
p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { |
|
if (do_notify_parent(p, p->exit_signal)) { |
|
p->exit_state = EXIT_DEAD; |
|
list_move_tail(&p->sibling, dead); |
|
} |
|
} |
|
|
|
kill_orphaned_pgrp(p, father); |
|
} |
|
|
|
static void forget_original_parent(struct task_struct *father) |
|
{ |
|
struct task_struct *p, *n, *reaper; |
|
LIST_HEAD(dead_children); |
|
|
|
write_lock_irq(&tasklist_lock); |
|
/* |
|
* Note that exit_ptrace() and find_new_reaper() might |
|
* drop tasklist_lock and reacquire it. |
|
*/ |
|
exit_ptrace(father); |
|
reaper = find_new_reaper(father); |
|
|
|
list_for_each_entry_safe(p, n, &father->children, sibling) { |
|
struct task_struct *t = p; |
|
do { |
|
t->real_parent = reaper; |
|
if (t->parent == father) { |
|
BUG_ON(t->ptrace); |
|
t->parent = t->real_parent; |
|
} |
|
if (t->pdeath_signal) |
|
group_send_sig_info(t->pdeath_signal, |
|
SEND_SIG_NOINFO, t); |
|
} while_each_thread(p, t); |
|
reparent_leader(father, p, &dead_children); |
|
} |
|
write_unlock_irq(&tasklist_lock); |
|
|
|
BUG_ON(!list_empty(&father->children)); |
|
|
|
list_for_each_entry_safe(p, n, &dead_children, sibling) { |
|
list_del_init(&p->sibling); |
|
release_task(p); |
|
} |
|
} |
|
|
|
/* |
|
* Send signals to all our closest relatives so that they know |
|
* to properly mourn us.. |
|
*/ |
|
static void exit_notify(struct task_struct *tsk, int group_dead) |
|
{ |
|
bool autoreap; |
|
|
|
/* |
|
* This does two things: |
|
* |
|
* A. Make init inherit all the child processes |
|
* B. Check to see if any process groups have become orphaned |
|
* as a result of our exiting, and if they have any stopped |
|
* jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
|
*/ |
|
forget_original_parent(tsk); |
|
exit_task_namespaces(tsk); |
|
|
|
write_lock_irq(&tasklist_lock); |
|
if (group_dead) |
|
kill_orphaned_pgrp(tsk->group_leader, NULL); |
|
|
|
if (unlikely(tsk->ptrace)) { |
|
int sig = thread_group_leader(tsk) && |
|
thread_group_empty(tsk) && |
|
!ptrace_reparented(tsk) ? |
|
tsk->exit_signal : SIGCHLD; |
|
autoreap = do_notify_parent(tsk, sig); |
|
} else if (thread_group_leader(tsk)) { |
|
autoreap = thread_group_empty(tsk) && |
|
do_notify_parent(tsk, tsk->exit_signal); |
|
} else { |
|
autoreap = true; |
|
} |
|
|
|
tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE; |
|
|
|
/* mt-exec, de_thread() is waiting for group leader */ |
|
if (unlikely(tsk->signal->notify_count < 0)) |
|
wake_up_process(tsk->signal->group_exit_task); |
|
write_unlock_irq(&tasklist_lock); |
|
|
|
/* If the process is dead, release it - nobody will wait for it */ |
|
if (autoreap) |
|
release_task(tsk); |
|
} |
|
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE |
|
static void check_stack_usage(void) |
|
{ |
|
static DEFINE_SPINLOCK(low_water_lock); |
|
static int lowest_to_date = THREAD_SIZE; |
|
unsigned long free; |
|
|
|
free = stack_not_used(current); |
|
|
|
if (free >= lowest_to_date) |
|
return; |
|
|
|
spin_lock(&low_water_lock); |
|
if (free < lowest_to_date) { |
|
printk(KERN_WARNING "%s (%d) used greatest stack depth: " |
|
"%lu bytes left\n", |
|
current->comm, task_pid_nr(current), free); |
|
lowest_to_date = free; |
|
} |
|
spin_unlock(&low_water_lock); |
|
} |
|
#else |
|
static inline void check_stack_usage(void) {} |
|
#endif |
|
|
|
void do_exit(long code) |
|
{ |
|
struct task_struct *tsk = current; |
|
int group_dead; |
|
|
|
profile_task_exit(tsk); |
|
|
|
WARN_ON(blk_needs_flush_plug(tsk)); |
|
|
|
if (unlikely(in_interrupt())) |
|
panic("Aiee, killing interrupt handler!"); |
|
if (unlikely(!tsk->pid)) |
|
panic("Attempted to kill the idle task!"); |
|
|
|
/* |
|
* If do_exit is called because this processes oopsed, it's possible |
|
* that get_fs() was left as KERNEL_DS, so reset it to USER_DS before |
|
* continuing. Amongst other possible reasons, this is to prevent |
|
* mm_release()->clear_child_tid() from writing to a user-controlled |
|
* kernel address. |
|
*/ |
|
set_fs(USER_DS); |
|
|
|
ptrace_event(PTRACE_EVENT_EXIT, code); |
|
|
|
validate_creds_for_do_exit(tsk); |
|
|
|
/* |
|
* We're taking recursive faults here in do_exit. Safest is to just |
|
* leave this task alone and wait for reboot. |
|
*/ |
|
if (unlikely(tsk->flags & PF_EXITING)) { |
|
printk(KERN_ALERT |
|
"Fixing recursive fault but reboot is needed!\n"); |
|
/* |
|
* We can do this unlocked here. The futex code uses |
|
* this flag just to verify whether the pi state |
|
* cleanup has been done or not. In the worst case it |
|
* loops once more. We pretend that the cleanup was |
|
* done as there is no way to return. Either the |
|
* OWNER_DIED bit is set by now or we push the blocked |
|
* task into the wait for ever nirwana as well. |
|
*/ |
|
tsk->flags |= PF_EXITPIDONE; |
|
set_current_state(TASK_UNINTERRUPTIBLE); |
|
schedule(); |
|
} |
|
|
|
exit_signals(tsk); /* sets PF_EXITING */ |
|
/* |
|
* tsk->flags are checked in the futex code to protect against |
|
* an exiting task cleaning up the robust pi futexes. |
|
*/ |
|
smp_mb(); |
|
raw_spin_unlock_wait(&tsk->pi_lock); |
|
|
|
if (unlikely(in_atomic())) |
|
printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", |
|
current->comm, task_pid_nr(current), |
|
preempt_count()); |
|
|
|
acct_update_integrals(tsk); |
|
/* sync mm's RSS info before statistics gathering */ |
|
if (tsk->mm) |
|
sync_mm_rss(tsk->mm); |
|
group_dead = atomic_dec_and_test(&tsk->signal->live); |
|
if (group_dead) { |
|
hrtimer_cancel(&tsk->signal->real_timer); |
|
exit_itimers(tsk->signal); |
|
if (tsk->mm) |
|
setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); |
|
} |
|
acct_collect(code, group_dead); |
|
if (group_dead) |
|
tty_audit_exit(); |
|
audit_free(tsk); |
|
|
|
tsk->exit_code = code; |
|
taskstats_exit(tsk, group_dead); |
|
|
|
exit_mm(tsk); |
|
|
|
if (group_dead) |
|
acct_process(); |
|
trace_sched_process_exit(tsk); |
|
|
|
exit_sem(tsk); |
|
exit_shm(tsk); |
|
exit_files(tsk); |
|
exit_fs(tsk); |
|
exit_task_work(tsk); |
|
check_stack_usage(); |
|
exit_thread(); |
|
|
|
/* |
|
* Flush inherited counters to the parent - before the parent |
|
* gets woken up by child-exit notifications. |
|
* |
|
* because of cgroup mode, must be called before cgroup_exit() |
|
*/ |
|
perf_event_exit_task(tsk); |
|
|
|
cgroup_exit(tsk, 1); |
|
|
|
if (group_dead) |
|
disassociate_ctty(1); |
|
|
|
module_put(task_thread_info(tsk)->exec_domain->module); |
|
|
|
proc_exit_connector(tsk); |
|
|
|
/* |
|
* FIXME: do that only when needed, using sched_exit tracepoint |
|
*/ |
|
ptrace_put_breakpoints(tsk); |
|
|
|
exit_notify(tsk, group_dead); |
|
#ifdef CONFIG_NUMA |
|
task_lock(tsk); |
|
mpol_put(tsk->mempolicy); |
|
tsk->mempolicy = NULL; |
|
task_unlock(tsk); |
|
#endif |
|
#ifdef CONFIG_FUTEX |
|
if (unlikely(current->pi_state_cache)) |
|
kfree(current->pi_state_cache); |
|
#endif |
|
/* |
|
* Make sure we are holding no locks: |
|
*/ |
|
debug_check_no_locks_held(tsk); |
|
/* |
|
* We can do this unlocked here. The futex code uses this flag |
|
* just to verify whether the pi state cleanup has been done |
|
* or not. In the worst case it loops once more. |
|
*/ |
|
tsk->flags |= PF_EXITPIDONE; |
|
|
|
if (tsk->io_context) |
|
exit_io_context(tsk); |
|
|
|
if (tsk->splice_pipe) |
|
__free_pipe_info(tsk->splice_pipe); |
|
|
|
validate_creds_for_do_exit(tsk); |
|
|
|
preempt_disable(); |
|
if (tsk->nr_dirtied) |
|
__this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); |
|
exit_rcu(); |
|
|
|
/* |
|
* The setting of TASK_RUNNING by try_to_wake_up() may be delayed |
|
* when the following two conditions become true. |
|
* - There is race condition of mmap_sem (It is acquired by |
|
* exit_mm()), and |
|
* - SMI occurs before setting TASK_RUNINNG. |
|
* (or hypervisor of virtual machine switches to other guest) |
|
* As a result, we may become TASK_RUNNING after becoming TASK_DEAD |
|
* |
|
* To avoid it, we have to wait for releasing tsk->pi_lock which |
|
* is held by try_to_wake_up() |
|
*/ |
|
smp_mb(); |
|
raw_spin_unlock_wait(&tsk->pi_lock); |
|
|
|
/* causes final put_task_struct in finish_task_switch(). */ |
|
tsk->state = TASK_DEAD; |
|
tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */ |
|
schedule(); |
|
BUG(); |
|
/* Avoid "noreturn function does return". */ |
|
for (;;) |
|
cpu_relax(); /* For when BUG is null */ |
|
} |
|
|
|
EXPORT_SYMBOL_GPL(do_exit); |
|
|
|
void complete_and_exit(struct completion *comp, long code) |
|
{ |
|
if (comp) |
|
complete(comp); |
|
|
|
do_exit(code); |
|
} |
|
|
|
EXPORT_SYMBOL(complete_and_exit); |
|
|
|
SYSCALL_DEFINE1(exit, int, error_code) |
|
{ |
|
do_exit((error_code&0xff)<<8); |
|
} |
|
|
|
/* |
|
* Take down every thread in the group. This is called by fatal signals |
|
* as well as by sys_exit_group (below). |
|
*/ |
|
void |
|
do_group_exit(int exit_code) |
|
{ |
|
struct signal_struct *sig = current->signal; |
|
|
|
BUG_ON(exit_code & 0x80); /* core dumps don't get here */ |
|
|
|
if (signal_group_exit(sig)) |
|
exit_code = sig->group_exit_code; |
|
else if (!thread_group_empty(current)) { |
|
struct sighand_struct *const sighand = current->sighand; |
|
spin_lock_irq(&sighand->siglock); |
|
if (signal_group_exit(sig)) |
|
/* Another thread got here before we took the lock. */ |
|
exit_code = sig->group_exit_code; |
|
else { |
|
sig->group_exit_code = exit_code; |
|
sig->flags = SIGNAL_GROUP_EXIT; |
|
zap_other_threads(current); |
|
} |
|
spin_unlock_irq(&sighand->siglock); |
|
} |
|
|
|
do_exit(exit_code); |
|
/* NOTREACHED */ |
|
} |
|
|
|
/* |
|
* this kills every thread in the thread group. Note that any externally |
|
* wait4()-ing process will get the correct exit code - even if this |
|
* thread is not the thread group leader. |
|
*/ |
|
SYSCALL_DEFINE1(exit_group, int, error_code) |
|
{ |
|
do_group_exit((error_code & 0xff) << 8); |
|
/* NOTREACHED */ |
|
return 0; |
|
} |
|
|
|
struct wait_opts { |
|
enum pid_type wo_type; |
|
int wo_flags; |
|
struct pid *wo_pid; |
|
|
|
struct siginfo __user *wo_info; |
|
int __user *wo_stat; |
|
struct rusage __user *wo_rusage; |
|
|
|
wait_queue_t child_wait; |
|
int notask_error; |
|
}; |
|
|
|
static inline |
|
struct pid *task_pid_type(struct task_struct *task, enum pid_type type) |
|
{ |
|
if (type != PIDTYPE_PID) |
|
task = task->group_leader; |
|
return task->pids[type].pid; |
|
} |
|
|
|
static int eligible_pid(struct wait_opts *wo, struct task_struct *p) |
|
{ |
|
return wo->wo_type == PIDTYPE_MAX || |
|
task_pid_type(p, wo->wo_type) == wo->wo_pid; |
|
} |
|
|
|
static int eligible_child(struct wait_opts *wo, struct task_struct *p) |
|
{ |
|
if (!eligible_pid(wo, p)) |
|
return 0; |
|
/* Wait for all children (clone and not) if __WALL is set; |
|
* otherwise, wait for clone children *only* if __WCLONE is |
|
* set; otherwise, wait for non-clone children *only*. (Note: |
|
* A "clone" child here is one that reports to its parent |
|
* using a signal other than SIGCHLD.) */ |
|
if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) |
|
&& !(wo->wo_flags & __WALL)) |
|
return 0; |
|
|
|
return 1; |
|
} |
|
|
|
static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p, |
|
pid_t pid, uid_t uid, int why, int status) |
|
{ |
|
struct siginfo __user *infop; |
|
int retval = wo->wo_rusage |
|
? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; |
|
|
|
put_task_struct(p); |
|
infop = wo->wo_info; |
|
if (infop) { |
|
if (!retval) |
|
retval = put_user(SIGCHLD, &infop->si_signo); |
|
if (!retval) |
|
retval = put_user(0, &infop->si_errno); |
|
if (!retval) |
|
retval = put_user((short)why, &infop->si_code); |
|
if (!retval) |
|
retval = put_user(pid, &infop->si_pid); |
|
if (!retval) |
|
retval = put_user(uid, &infop->si_uid); |
|
if (!retval) |
|
retval = put_user(status, &infop->si_status); |
|
} |
|
if (!retval) |
|
retval = pid; |
|
return retval; |
|
} |
|
|
|
/* |
|
* Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold |
|
* read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
|
* the lock and this task is uninteresting. If we return nonzero, we have |
|
* released the lock and the system call should return. |
|
*/ |
|
static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) |
|
{ |
|
unsigned long state; |
|
int retval, status, traced; |
|
pid_t pid = task_pid_vnr(p); |
|
uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
|
struct siginfo __user *infop; |
|
|
|
if (!likely(wo->wo_flags & WEXITED)) |
|
return 0; |
|
|
|
if (unlikely(wo->wo_flags & WNOWAIT)) { |
|
int exit_code = p->exit_code; |
|
int why; |
|
|
|
get_task_struct(p); |
|
read_unlock(&tasklist_lock); |
|
if ((exit_code & 0x7f) == 0) { |
|
why = CLD_EXITED; |
|
status = exit_code >> 8; |
|
} else { |
|
why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED; |
|
status = exit_code & 0x7f; |
|
} |
|
return wait_noreap_copyout(wo, p, pid, uid, why, status); |
|
} |
|
|
|
/* |
|
* Try to move the task's state to DEAD |
|
* only one thread is allowed to do this: |
|
*/ |
|
state = xchg(&p->exit_state, EXIT_DEAD); |
|
if (state != EXIT_ZOMBIE) { |
|
BUG_ON(state != EXIT_DEAD); |
|
return 0; |
|
} |
|
|
|
traced = ptrace_reparented(p); |
|
/* |
|
* It can be ptraced but not reparented, check |
|
* thread_group_leader() to filter out sub-threads. |
|
*/ |
|
if (likely(!traced) && thread_group_leader(p)) { |
|
struct signal_struct *psig; |
|
struct signal_struct *sig; |
|
unsigned long maxrss; |
|
cputime_t tgutime, tgstime; |
|
|
|
/* |
|
* The resource counters for the group leader are in its |
|
* own task_struct. Those for dead threads in the group |
|
* are in its signal_struct, as are those for the child |
|
* processes it has previously reaped. All these |
|
* accumulate in the parent's signal_struct c* fields. |
|
* |
|
* We don't bother to take a lock here to protect these |
|
* p->signal fields, because they are only touched by |
|
* __exit_signal, which runs with tasklist_lock |
|
* write-locked anyway, and so is excluded here. We do |
|
* need to protect the access to parent->signal fields, |
|
* as other threads in the parent group can be right |
|
* here reaping other children at the same time. |
|
* |
|
* We use thread_group_times() to get times for the thread |
|
* group, which consolidates times for all threads in the |
|
* group including the group leader. |
|
*/ |
|
thread_group_times(p, &tgutime, &tgstime); |
|
spin_lock_irq(&p->real_parent->sighand->siglock); |
|
psig = p->real_parent->signal; |
|
sig = p->signal; |
|
psig->cutime += tgutime + sig->cutime; |
|
psig->cstime += tgstime + sig->cstime; |
|
psig->cgtime += p->gtime + sig->gtime + sig->cgtime; |
|
psig->cmin_flt += |
|
p->min_flt + sig->min_flt + sig->cmin_flt; |
|
psig->cmaj_flt += |
|
p->maj_flt + sig->maj_flt + sig->cmaj_flt; |
|
psig->cnvcsw += |
|
p->nvcsw + sig->nvcsw + sig->cnvcsw; |
|
psig->cnivcsw += |
|
p->nivcsw + sig->nivcsw + sig->cnivcsw; |
|
psig->cinblock += |
|
task_io_get_inblock(p) + |
|
sig->inblock + sig->cinblock; |
|
psig->coublock += |
|
task_io_get_oublock(p) + |
|
sig->oublock + sig->coublock; |
|
maxrss = max(sig->maxrss, sig->cmaxrss); |
|
if (psig->cmaxrss < maxrss) |
|
psig->cmaxrss = maxrss; |
|
task_io_accounting_add(&psig->ioac, &p->ioac); |
|
task_io_accounting_add(&psig->ioac, &sig->ioac); |
|
spin_unlock_irq(&p->real_parent->sighand->siglock); |
|
} |
|
|
|
/* |
|
* Now we are sure this task is interesting, and no other |
|
* thread can reap it because we set its state to EXIT_DEAD. |
|
*/ |
|
read_unlock(&tasklist_lock); |
|
|
|
retval = wo->wo_rusage |
|
? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; |
|
status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
|
? p->signal->group_exit_code : p->exit_code; |
|
if (!retval && wo->wo_stat) |
|
retval = put_user(status, wo->wo_stat); |
|
|
|
infop = wo->wo_info; |
|
if (!retval && infop) |
|
retval = put_user(SIGCHLD, &infop->si_signo); |
|
if (!retval && infop) |
|
retval = put_user(0, &infop->si_errno); |
|
if (!retval && infop) { |
|
int why; |
|
|
|
if ((status & 0x7f) == 0) { |
|
why = CLD_EXITED; |
|
status >>= 8; |
|
} else { |
|
why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; |
|
status &= 0x7f; |
|
} |
|
retval = put_user((short)why, &infop->si_code); |
|
if (!retval) |
|
retval = put_user(status, &infop->si_status); |
|
} |
|
if (!retval && infop) |
|
retval = put_user(pid, &infop->si_pid); |
|
if (!retval && infop) |
|
retval = put_user(uid, &infop->si_uid); |
|
if (!retval) |
|
retval = pid; |
|
|
|
if (traced) { |
|
write_lock_irq(&tasklist_lock); |
|
/* We dropped tasklist, ptracer could die and untrace */ |
|
ptrace_unlink(p); |
|
/* |
|
* If this is not a sub-thread, notify the parent. |
|
* If parent wants a zombie, don't release it now. |
|
*/ |
|
if (thread_group_leader(p) && |
|
!do_notify_parent(p, p->exit_signal)) { |
|
p->exit_state = EXIT_ZOMBIE; |
|
p = NULL; |
|
} |
|
write_unlock_irq(&tasklist_lock); |
|
} |
|
if (p != NULL) |
|
release_task(p); |
|
|
|
return retval; |
|
} |
|
|
|
static int *task_stopped_code(struct task_struct *p, bool ptrace) |
|
{ |
|
if (ptrace) { |
|
if (task_is_stopped_or_traced(p) && |
|
!(p->jobctl & JOBCTL_LISTENING)) |
|
return &p->exit_code; |
|
} else { |
|
if (p->signal->flags & SIGNAL_STOP_STOPPED) |
|
return &p->signal->group_exit_code; |
|
} |
|
return NULL; |
|
} |
|
|
|
/** |
|
* wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED |
|
* @wo: wait options |
|
* @ptrace: is the wait for ptrace |
|
* @p: task to wait for |
|
* |
|
* Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. |
|
* |
|
* CONTEXT: |
|
* read_lock(&tasklist_lock), which is released if return value is |
|
* non-zero. Also, grabs and releases @p->sighand->siglock. |
|
* |
|
* RETURNS: |
|
* 0 if wait condition didn't exist and search for other wait conditions |
|
* should continue. Non-zero return, -errno on failure and @p's pid on |
|
* success, implies that tasklist_lock is released and wait condition |
|
* search should terminate. |
|
*/ |
|
static int wait_task_stopped(struct wait_opts *wo, |
|
int ptrace, struct task_struct *p) |
|
{ |
|
struct siginfo __user *infop; |
|
int retval, exit_code, *p_code, why; |
|
uid_t uid = 0; /* unneeded, required by compiler */ |
|
pid_t pid; |
|
|
|
/* |
|
* Traditionally we see ptrace'd stopped tasks regardless of options. |
|
*/ |
|
if (!ptrace && !(wo->wo_flags & WUNTRACED)) |
|
return 0; |
|
|
|
if (!task_stopped_code(p, ptrace)) |
|
return 0; |
|
|
|
exit_code = 0; |
|
spin_lock_irq(&p->sighand->siglock); |
|
|
|
p_code = task_stopped_code(p, ptrace); |
|
if (unlikely(!p_code)) |
|
goto unlock_sig; |
|
|
|
exit_code = *p_code; |
|
if (!exit_code) |
|
goto unlock_sig; |
|
|
|
if (!unlikely(wo->wo_flags & WNOWAIT)) |
|
*p_code = 0; |
|
|
|
uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
|
unlock_sig: |
|
spin_unlock_irq(&p->sighand->siglock); |
|
if (!exit_code) |
|
return 0; |
|
|
|
/* |
|
* Now we are pretty sure this task is interesting. |
|
* Make sure it doesn't get reaped out from under us while we |
|
* give up the lock and then examine it below. We don't want to |
|
* keep holding onto the tasklist_lock while we call getrusage and |
|
* possibly take page faults for user memory. |
|
*/ |
|
get_task_struct(p); |
|
pid = task_pid_vnr(p); |
|
why = ptrace ? CLD_TRAPPED : CLD_STOPPED; |
|
read_unlock(&tasklist_lock); |
|
|
|
if (unlikely(wo->wo_flags & WNOWAIT)) |
|
return wait_noreap_copyout(wo, p, pid, uid, why, exit_code); |
|
|
|
retval = wo->wo_rusage |
|
? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; |
|
if (!retval && wo->wo_stat) |
|
retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat); |
|
|
|
infop = wo->wo_info; |
|
if (!retval && infop) |
|
retval = put_user(SIGCHLD, &infop->si_signo); |
|
if (!retval && infop) |
|
retval = put_user(0, &infop->si_errno); |
|
if (!retval && infop) |
|
retval = put_user((short)why, &infop->si_code); |
|
if (!retval && infop) |
|
retval = put_user(exit_code, &infop->si_status); |
|
if (!retval && infop) |
|
retval = put_user(pid, &infop->si_pid); |
|
if (!retval && infop) |
|
retval = put_user(uid, &infop->si_uid); |
|
if (!retval) |
|
retval = pid; |
|
put_task_struct(p); |
|
|
|
BUG_ON(!retval); |
|
return retval; |
|
} |
|
|
|
/* |
|
* Handle do_wait work for one task in a live, non-stopped state. |
|
* read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
|
* the lock and this task is uninteresting. If we return nonzero, we have |
|
* released the lock and the system call should return. |
|
*/ |
|
static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) |
|
{ |
|
int retval; |
|
pid_t pid; |
|
uid_t uid; |
|
|
|
if (!unlikely(wo->wo_flags & WCONTINUED)) |
|
return 0; |
|
|
|
if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) |
|
return 0; |
|
|
|
spin_lock_irq(&p->sighand->siglock); |
|
/* Re-check with the lock held. */ |
|
if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { |
|
spin_unlock_irq(&p->sighand->siglock); |
|
return 0; |
|
} |
|
if (!unlikely(wo->wo_flags & WNOWAIT)) |
|
p->signal->flags &= ~SIGNAL_STOP_CONTINUED; |
|
uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
|
spin_unlock_irq(&p->sighand->siglock); |
|
|
|
pid = task_pid_vnr(p); |
|
get_task_struct(p); |
|
read_unlock(&tasklist_lock); |
|
|
|
if (!wo->wo_info) { |
|
retval = wo->wo_rusage |
|
? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; |
|
put_task_struct(p); |
|
if (!retval && wo->wo_stat) |
|
retval = put_user(0xffff, wo->wo_stat); |
|
if (!retval) |
|
retval = pid; |
|
} else { |
|
retval = wait_noreap_copyout(wo, p, pid, uid, |
|
CLD_CONTINUED, SIGCONT); |
|
BUG_ON(retval == 0); |
|
} |
|
|
|
return retval; |
|
} |
|
|
|
/* |
|
* Consider @p for a wait by @parent. |
|
* |
|
* -ECHILD should be in ->notask_error before the first call. |
|
* Returns nonzero for a final return, when we have unlocked tasklist_lock. |
|
* Returns zero if the search for a child should continue; |
|
* then ->notask_error is 0 if @p is an eligible child, |
|
* or another error from security_task_wait(), or still -ECHILD. |
|
*/ |
|
static int wait_consider_task(struct wait_opts *wo, int ptrace, |
|
struct task_struct *p) |
|
{ |
|
int ret = eligible_child(wo, p); |
|
if (!ret) |
|
return ret; |
|
|
|
ret = security_task_wait(p); |
|
if (unlikely(ret < 0)) { |
|
/* |
|
* If we have not yet seen any eligible child, |
|
* then let this error code replace -ECHILD. |
|
* A permission error will give the user a clue |
|
* to look for security policy problems, rather |
|
* than for mysterious wait bugs. |
|
*/ |
|
if (wo->notask_error) |
|
wo->notask_error = ret; |
|
return 0; |
|
} |
|
|
|
/* dead body doesn't have much to contribute */ |
|
if (unlikely(p->exit_state == EXIT_DEAD)) { |
|
/* |
|
* But do not ignore this task until the tracer does |
|
* wait_task_zombie()->do_notify_parent(). |
|
*/ |
|
if (likely(!ptrace) && unlikely(ptrace_reparented(p))) |
|
wo->notask_error = 0; |
|
return 0; |
|
} |
|
|
|
/* slay zombie? */ |
|
if (p->exit_state == EXIT_ZOMBIE) { |
|
/* |
|
* A zombie ptracee is only visible to its ptracer. |
|
* Notification and reaping will be cascaded to the real |
|
* parent when the ptracer detaches. |
|
*/ |
|
if (likely(!ptrace) && unlikely(p->ptrace)) { |
|
/* it will become visible, clear notask_error */ |
|
wo->notask_error = 0; |
|
return 0; |
|
} |
|
|
|
/* we don't reap group leaders with subthreads */ |
|
if (!delay_group_leader(p)) |
|
return wait_task_zombie(wo, p); |
|
|
|
/* |
|
* Allow access to stopped/continued state via zombie by |
|
* falling through. Clearing of notask_error is complex. |
|
* |
|
* When !@ptrace: |
|
* |
|
* If WEXITED is set, notask_error should naturally be |
|
* cleared. If not, subset of WSTOPPED|WCONTINUED is set, |
|
* so, if there are live subthreads, there are events to |
|
* wait for. If all subthreads are dead, it's still safe |
|
* to clear - this function will be called again in finite |
|
* amount time once all the subthreads are released and |
|
* will then return without clearing. |
|
* |
|
* When @ptrace: |
|
* |
|
* Stopped state is per-task and thus can't change once the |
|
* target task dies. Only continued and exited can happen. |
|
* Clear notask_error if WCONTINUED | WEXITED. |
|
*/ |
|
if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) |
|
wo->notask_error = 0; |
|
} else { |
|
/* |
|
* If @p is ptraced by a task in its real parent's group, |
|
* hide group stop/continued state when looking at @p as |
|
* the real parent; otherwise, a single stop can be |
|
* reported twice as group and ptrace stops. |
|
* |
|
* If a ptracer wants to distinguish the two events for its |
|
* own children, it should create a separate process which |
|
* takes the role of real parent. |
|
*/ |
|
if (likely(!ptrace) && p->ptrace && !ptrace_reparented(p)) |
|
return 0; |
|
|
|
/* |
|
* @p is alive and it's gonna stop, continue or exit, so |
|
* there always is something to wait for. |
|
*/ |
|
wo->notask_error = 0; |
|
} |
|
|
|
/* |
|
* Wait for stopped. Depending on @ptrace, different stopped state |
|
* is used and the two don't interact with each other. |
|
*/ |
|
ret = wait_task_stopped(wo, ptrace, p); |
|
if (ret) |
|
return ret; |
|
|
|
/* |
|
* Wait for continued. There's only one continued state and the |
|
* ptracer can consume it which can confuse the real parent. Don't |
|
* use WCONTINUED from ptracer. You don't need or want it. |
|
*/ |
|
return wait_task_continued(wo, p); |
|
} |
|
|
|
/* |
|
* Do the work of do_wait() for one thread in the group, @tsk. |
|
* |
|
* -ECHILD should be in ->notask_error before the first call. |
|
* Returns nonzero for a final return, when we have unlocked tasklist_lock. |
|
* Returns zero if the search for a child should continue; then |
|
* ->notask_error is 0 if there were any eligible children, |
|
* or another error from security_task_wait(), or still -ECHILD. |
|
*/ |
|
static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) |
|
{ |
|
struct task_struct *p; |
|
|
|
list_for_each_entry(p, &tsk->children, sibling) { |
|
int ret = wait_consider_task(wo, 0, p); |
|
if (ret) |
|
return ret; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) |
|
{ |
|
struct task_struct *p; |
|
|
|
list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { |
|
int ret = wait_consider_task(wo, 1, p); |
|
if (ret) |
|
return ret; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static int child_wait_callback(wait_queue_t *wait, unsigned mode, |
|
int sync, void *key) |
|
{ |
|
struct wait_opts *wo = container_of(wait, struct wait_opts, |
|
child_wait); |
|
struct task_struct *p = key; |
|
|
|
if (!eligible_pid(wo, p)) |
|
return 0; |
|
|
|
if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) |
|
return 0; |
|
|
|
return default_wake_function(wait, mode, sync, key); |
|
} |
|
|
|
void __wake_up_parent(struct task_struct *p, struct task_struct *parent) |
|
{ |
|
__wake_up_sync_key(&parent->signal->wait_chldexit, |
|
TASK_INTERRUPTIBLE, 1, p); |
|
} |
|
|
|
static long do_wait(struct wait_opts *wo) |
|
{ |
|
struct task_struct *tsk; |
|
int retval; |
|
|
|
trace_sched_process_wait(wo->wo_pid); |
|
|
|
init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); |
|
wo->child_wait.private = current; |
|
add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
|
repeat: |
|
/* |
|
* If there is nothing that can match our critiera just get out. |
|
* We will clear ->notask_error to zero if we see any child that |
|
* might later match our criteria, even if we are not able to reap |
|
* it yet. |
|
*/ |
|
wo->notask_error = -ECHILD; |
|
if ((wo->wo_type < PIDTYPE_MAX) && |
|
(!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type]))) |
|
goto notask; |
|
|
|
set_current_state(TASK_INTERRUPTIBLE); |
|
read_lock(&tasklist_lock); |
|
tsk = current; |
|
do { |
|
retval = do_wait_thread(wo, tsk); |
|
if (retval) |
|
goto end; |
|
|
|
retval = ptrace_do_wait(wo, tsk); |
|
if (retval) |
|
goto end; |
|
|
|
if (wo->wo_flags & __WNOTHREAD) |
|
break; |
|
} while_each_thread(current, tsk); |
|
read_unlock(&tasklist_lock); |
|
|
|
notask: |
|
retval = wo->notask_error; |
|
if (!retval && !(wo->wo_flags & WNOHANG)) { |
|
retval = -ERESTARTSYS; |
|
if (!signal_pending(current)) { |
|
schedule(); |
|
goto repeat; |
|
} |
|
} |
|
end: |
|
__set_current_state(TASK_RUNNING); |
|
remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
|
return retval; |
|
} |
|
|
|
SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, |
|
infop, int, options, struct rusage __user *, ru) |
|
{ |
|
struct wait_opts wo; |
|
struct pid *pid = NULL; |
|
enum pid_type type; |
|
long ret; |
|
|
|
if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED)) |
|
return -EINVAL; |
|
if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) |
|
return -EINVAL; |
|
|
|
switch (which) { |
|
case P_ALL: |
|
type = PIDTYPE_MAX; |
|
break; |
|
case P_PID: |
|
type = PIDTYPE_PID; |
|
if (upid <= 0) |
|
return -EINVAL; |
|
break; |
|
case P_PGID: |
|
type = PIDTYPE_PGID; |
|
if (upid <= 0) |
|
return -EINVAL; |
|
break; |
|
default: |
|
return -EINVAL; |
|
} |
|
|
|
if (type < PIDTYPE_MAX) |
|
pid = find_get_pid(upid); |
|
|
|
wo.wo_type = type; |
|
wo.wo_pid = pid; |
|
wo.wo_flags = options; |
|
wo.wo_info = infop; |
|
wo.wo_stat = NULL; |
|
wo.wo_rusage = ru; |
|
ret = do_wait(&wo); |
|
|
|
if (ret > 0) { |
|
ret = 0; |
|
} else if (infop) { |
|
/* |
|
* For a WNOHANG return, clear out all the fields |
|
* we would set so the user can easily tell the |
|
* difference. |
|
*/ |
|
if (!ret) |
|
ret = put_user(0, &infop->si_signo); |
|
if (!ret) |
|
ret = put_user(0, &infop->si_errno); |
|
if (!ret) |
|
ret = put_user(0, &infop->si_code); |
|
if (!ret) |
|
ret = put_user(0, &infop->si_pid); |
|
if (!ret) |
|
ret = put_user(0, &infop->si_uid); |
|
if (!ret) |
|
ret = put_user(0, &infop->si_status); |
|
} |
|
|
|
put_pid(pid); |
|
|
|
/* avoid REGPARM breakage on x86: */ |
|
asmlinkage_protect(5, ret, which, upid, infop, options, ru); |
|
return ret; |
|
} |
|
|
|
SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, |
|
int, options, struct rusage __user *, ru) |
|
{ |
|
struct wait_opts wo; |
|
struct pid *pid = NULL; |
|
enum pid_type type; |
|
long ret; |
|
|
|
if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| |
|
__WNOTHREAD|__WCLONE|__WALL)) |
|
return -EINVAL; |
|
|
|
if (upid == -1) |
|
type = PIDTYPE_MAX; |
|
else if (upid < 0) { |
|
type = PIDTYPE_PGID; |
|
pid = find_get_pid(-upid); |
|
} else if (upid == 0) { |
|
type = PIDTYPE_PGID; |
|
pid = get_task_pid(current, PIDTYPE_PGID); |
|
} else /* upid > 0 */ { |
|
type = PIDTYPE_PID; |
|
pid = find_get_pid(upid); |
|
} |
|
|
|
wo.wo_type = type; |
|
wo.wo_pid = pid; |
|
wo.wo_flags = options | WEXITED; |
|
wo.wo_info = NULL; |
|
wo.wo_stat = stat_addr; |
|
wo.wo_rusage = ru; |
|
ret = do_wait(&wo); |
|
put_pid(pid); |
|
|
|
/* avoid REGPARM breakage on x86: */ |
|
asmlinkage_protect(4, ret, upid, stat_addr, options, ru); |
|
return ret; |
|
} |
|
|
|
#ifdef __ARCH_WANT_SYS_WAITPID |
|
|
|
/* |
|
* sys_waitpid() remains for compatibility. waitpid() should be |
|
* implemented by calling sys_wait4() from libc.a. |
|
*/ |
|
SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) |
|
{ |
|
return sys_wait4(pid, stat_addr, options, NULL); |
|
} |
|
|
|
#endif
|
|
|