header cleaning: don't include smp_lock.h when not used
[linux-3.10.git] / kernel / signal.c
index b29c868..1368e67 100644 (file)
  *             to allow signals to be sent reliably.
  */
 
-#include <linux/config.h>
 #include <linux/slab.h>
 #include <linux/module.h>
-#include <linux/smp_lock.h>
 #include <linux/init.h>
 #include <linux/sched.h>
 #include <linux/fs.h>
 #include <linux/security.h>
 #include <linux/syscalls.h>
 #include <linux/ptrace.h>
-#include <linux/posix-timers.h>
 #include <linux/signal.h>
-#include <linux/audit.h>
 #include <linux/capability.h>
+#include <linux/freezer.h>
+#include <linux/pid_namespace.h>
+#include <linux/nsproxy.h>
+
 #include <asm/param.h>
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
 #include <asm/siginfo.h>
+#include "audit.h"     /* audit_signal_info() */
 
 /*
  * SLAB caches for signal bits.
  */
 
-static kmem_cache_t *sigqueue_cachep;
+static struct kmem_cache *sigqueue_cachep;
 
 /*
  * In POSIX a signal is sent either to a specific thread (Linux task)
@@ -147,8 +148,7 @@ static kmem_cache_t *sigqueue_cachep;
 #define sig_kernel_stop(sig) \
                (((sig) < SIGRTMIN)  && T(sig, SIG_KERNEL_STOP_MASK))
 
-#define sig_needs_tasklist(sig) \
-               (((sig) < SIGRTMIN)  && T(sig, SIG_KERNEL_STOP_MASK | M(SIGCONT)))
+#define sig_needs_tasklist(sig)        ((sig) == SIGCONT)
 
 #define sig_user_defined(t, signr) \
        (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) &&  \
@@ -270,18 +270,25 @@ static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
                                         int override_rlimit)
 {
        struct sigqueue *q = NULL;
+       struct user_struct *user;
 
-       atomic_inc(&t->user->sigpending);
+       /*
+        * In order to avoid problems with "switch_user()", we want to make
+        * sure that the compiler doesn't re-load "t->user"
+        */
+       user = t->user;
+       barrier();
+       atomic_inc(&user->sigpending);
        if (override_rlimit ||
-           atomic_read(&t->user->sigpending) <=
+           atomic_read(&user->sigpending) <=
                        t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
                q = kmem_cache_alloc(sigqueue_cachep, flags);
        if (unlikely(q == NULL)) {
-               atomic_dec(&t->user->sigpending);
+               atomic_dec(&user->sigpending);
        } else {
                INIT_LIST_HEAD(&q->list);
                q->flags = 0;
-               q->user = get_uid(t->user);
+               q->user = get_uid(user);
        }
        return(q);
 }
@@ -295,7 +302,7 @@ static void __sigqueue_free(struct sigqueue *q)
        kmem_cache_free(sigqueue_cachep, q);
 }
 
-static void flush_sigqueue(struct sigpending *queue)
+void flush_sigqueue(struct sigpending *queue)
 {
        struct sigqueue *q;
 
@@ -322,68 +329,6 @@ void flush_signals(struct task_struct *t)
 }
 
 /*
- * This function expects the tasklist_lock write-locked.
- */
-void __exit_signal(struct task_struct *tsk)
-{
-       struct signal_struct *sig = tsk->signal;
-       struct sighand_struct *sighand;
-
-       BUG_ON(!sig);
-       BUG_ON(!atomic_read(&sig->count));
-
-       rcu_read_lock();
-       sighand = rcu_dereference(tsk->sighand);
-       spin_lock(&sighand->siglock);
-
-       posix_cpu_timers_exit(tsk);
-       if (atomic_dec_and_test(&sig->count))
-               posix_cpu_timers_exit_group(tsk);
-       else {
-               /*
-                * If there is any task waiting for the group exit
-                * then notify it:
-                */
-               if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
-                       wake_up_process(sig->group_exit_task);
-                       sig->group_exit_task = NULL;
-               }
-               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 = cputime_add(sig->utime, tsk->utime);
-               sig->stime = cputime_add(sig->stime, tsk->stime);
-               sig->min_flt += tsk->min_flt;
-               sig->maj_flt += tsk->maj_flt;
-               sig->nvcsw += tsk->nvcsw;
-               sig->nivcsw += tsk->nivcsw;
-               sig->sched_time += tsk->sched_time;
-               sig = NULL; /* Marker for below. */
-       }
-
-       tsk->signal = NULL;
-       cleanup_sighand(tsk);
-       spin_unlock(&sighand->siglock);
-       rcu_read_unlock();
-
-       clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
-       flush_sigqueue(&tsk->pending);
-       if (sig) {
-               flush_sigqueue(&sig->shared_pending);
-               __cleanup_signal(sig);
-       }
-}
-
-/*
  * Flush all handlers for a task.
  */
 
@@ -482,9 +427,8 @@ static int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
                        siginfo_t *info)
 {
-       int sig = 0;
+       int sig = next_signal(pending, mask);
 
-       sig = next_signal(pending, mask);
        if (sig) {
                if (current->notifier) {
                        if (sigismember(current->notifier_mask, sig)) {
@@ -497,9 +441,7 @@ static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
 
                if (!collect_signal(sig, pending, info))
                        sig = 0;
-                               
        }
-       recalc_sigpending();
 
        return sig;
 }
@@ -513,25 +455,50 @@ static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
 {
        int signr = __dequeue_signal(&tsk->pending, mask, info);
-       if (!signr)
+       if (!signr) {
                signr = __dequeue_signal(&tsk->signal->shared_pending,
                                         mask, info);
-       if (signr && unlikely(sig_kernel_stop(signr))) {
-               /*
-                * Set a marker that we have dequeued a stop signal.  Our
-                * caller might release the siglock and then the pending
-                * stop signal it is about to process is no longer in the
-                * pending bitmasks, but must still be cleared by a SIGCONT
-                * (and overruled by a SIGKILL).  So those cases clear this
-                * shared flag after we've set it.  Note that this flag may
-                * remain set after the signal we return is ignored or
-                * handled.  That doesn't matter because its only purpose
-                * is to alert stop-signal processing code when another
-                * processor has come along and cleared the flag.
-                */
-               if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
-                       tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
-       }
+               /*
+                * itimer signal ?
+                *
+                * itimers are process shared and we restart periodic
+                * itimers in the signal delivery path to prevent DoS
+                * attacks in the high resolution timer case. This is
+                * compliant with the old way of self restarting
+                * itimers, as the SIGALRM is a legacy signal and only
+                * queued once. Changing the restart behaviour to
+                * restart the timer in the signal dequeue path is
+                * reducing the timer noise on heavy loaded !highres
+                * systems too.
+                */
+               if (unlikely(signr == SIGALRM)) {
+                       struct hrtimer *tmr = &tsk->signal->real_timer;
+
+                       if (!hrtimer_is_queued(tmr) &&
+                           tsk->signal->it_real_incr.tv64 != 0) {
+                               hrtimer_forward(tmr, tmr->base->get_time(),
+                                               tsk->signal->it_real_incr);
+                               hrtimer_restart(tmr);
+                       }
+               }
+       }
+       recalc_sigpending_tsk(tsk);
+       if (signr && unlikely(sig_kernel_stop(signr))) {
+               /*
+                * Set a marker that we have dequeued a stop signal.  Our
+                * caller might release the siglock and then the pending
+                * stop signal it is about to process is no longer in the
+                * pending bitmasks, but must still be cleared by a SIGCONT
+                * (and overruled by a SIGKILL).  So those cases clear this
+                * shared flag after we've set it.  Note that this flag may
+                * remain set after the signal we return is ignored or
+                * handled.  That doesn't matter because its only purpose
+                * is to alert stop-signal processing code when another
+                * processor has come along and cleared the flag.
+                */
+               if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
+                       tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
+       }
        if ( signr &&
             ((info->si_code & __SI_MASK) == __SI_TIMER) &&
             info->si_sys_private){
@@ -642,22 +609,20 @@ static int check_kill_permission(int sig, struct siginfo *info,
        error = -EPERM;
        if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
            && ((sig != SIGCONT) ||
-               (current->signal->session != t->signal->session))
+               (process_session(current) != process_session(t)))
            && (current->euid ^ t->suid) && (current->euid ^ t->uid)
            && (current->uid ^ t->suid) && (current->uid ^ t->uid)
            && !capable(CAP_KILL))
                return error;
 
-       error = security_task_kill(t, info, sig);
+       error = security_task_kill(t, info, sig, 0);
        if (!error)
                audit_signal_info(sig, t); /* Let audit system see the signal */
        return error;
 }
 
 /* forward decl */
-static void do_notify_parent_cldstop(struct task_struct *tsk,
-                                    int to_self,
-                                    int why);
+static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
 
 /*
  * Handle magic process-wide effects of stop/continue signals.
@@ -707,7 +672,7 @@ static void handle_stop_signal(int sig, struct task_struct *p)
                        p->signal->group_stop_count = 0;
                        p->signal->flags = SIGNAL_STOP_CONTINUED;
                        spin_unlock(&p->sighand->siglock);
-                       do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_STOPPED);
+                       do_notify_parent_cldstop(p, CLD_STOPPED);
                        spin_lock(&p->sighand->siglock);
                }
                rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
@@ -748,7 +713,7 @@ static void handle_stop_signal(int sig, struct task_struct *p)
                        p->signal->flags = SIGNAL_STOP_CONTINUED;
                        p->signal->group_exit_code = 0;
                        spin_unlock(&p->sighand->siglock);
-                       do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_CONTINUED);
+                       do_notify_parent_cldstop(p, CLD_CONTINUED);
                        spin_lock(&p->sighand->siglock);
                } else {
                        /*
@@ -835,8 +800,7 @@ specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
 {
        int ret = 0;
 
-       if (!irqs_disabled())
-               BUG();
+       BUG_ON(!irqs_disabled());
        assert_spin_locked(&t->sighand->siglock);
 
        /* Short-circuit ignored signals.  */
@@ -859,22 +823,31 @@ out:
 /*
  * Force a signal that the process can't ignore: if necessary
  * we unblock the signal and change any SIG_IGN to SIG_DFL.
+ *
+ * Note: If we unblock the signal, we always reset it to SIG_DFL,
+ * since we do not want to have a signal handler that was blocked
+ * be invoked when user space had explicitly blocked it.
+ *
+ * We don't want to have recursive SIGSEGV's etc, for example.
  */
-
 int
 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
 {
        unsigned long int flags;
-       int ret;
+       int ret, blocked, ignored;
+       struct k_sigaction *action;
 
        spin_lock_irqsave(&t->sighand->siglock, flags);
-       if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) {
-               t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
-       }
-       if (sigismember(&t->blocked, sig)) {
-               sigdelset(&t->blocked, sig);
+       action = &t->sighand->action[sig-1];
+       ignored = action->sa.sa_handler == SIG_IGN;
+       blocked = sigismember(&t->blocked, sig);
+       if (blocked || ignored) {
+               action->sa.sa_handler = SIG_DFL;
+               if (blocked) {
+                       sigdelset(&t->blocked, sig);
+                       recalc_sigpending_tsk(t);
+               }
        }
-       recalc_sigpending_tsk(t);
        ret = specific_send_sig_info(sig, info, t);
        spin_unlock_irqrestore(&t->sighand->siglock, flags);
 
@@ -935,7 +908,6 @@ __group_complete_signal(int sig, struct task_struct *p)
                if (t == NULL)
                        /* restart balancing at this thread */
                        t = p->signal->curr_target = p;
-               BUG_ON(t->tgid != p->tgid);
 
                while (!wants_signal(sig, t)) {
                        t = next_thread(t);
@@ -1117,65 +1089,69 @@ int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
 }
 
 /*
- * kill_pg_info() sends a signal to a process group: this is what the tty
+ * kill_pgrp_info() sends a signal to a process group: this is what the tty
  * control characters do (^C, ^Z etc)
  */
 
-int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
+int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
 {
        struct task_struct *p = NULL;
        int retval, success;
 
-       if (pgrp <= 0)
-               return -EINVAL;
-
        success = 0;
        retval = -ESRCH;
-       do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
+       do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
                int err = group_send_sig_info(sig, info, p);
                success |= !err;
                retval = err;
-       } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
+       } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
        return success ? 0 : retval;
 }
 
-int
-kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
+int kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
 {
        int retval;
 
        read_lock(&tasklist_lock);
-       retval = __kill_pg_info(sig, info, pgrp);
+       retval = __kill_pgrp_info(sig, info, pgrp);
        read_unlock(&tasklist_lock);
 
        return retval;
 }
 
-int
-kill_proc_info(int sig, struct siginfo *info, pid_t pid)
+int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
 {
        int error;
-       int acquired_tasklist_lock = 0;
        struct task_struct *p;
 
        rcu_read_lock();
-       if (unlikely(sig_needs_tasklist(sig))) {
+       if (unlikely(sig_needs_tasklist(sig)))
                read_lock(&tasklist_lock);
-               acquired_tasklist_lock = 1;
-       }
-       p = find_task_by_pid(pid);
+
+       p = pid_task(pid, PIDTYPE_PID);
        error = -ESRCH;
        if (p)
                error = group_send_sig_info(sig, info, p);
-       if (unlikely(acquired_tasklist_lock))
+
+       if (unlikely(sig_needs_tasklist(sig)))
                read_unlock(&tasklist_lock);
        rcu_read_unlock();
        return error;
 }
 
-/* like kill_proc_info(), but doesn't use uid/euid of "current" */
-int kill_proc_info_as_uid(int sig, struct siginfo *info, pid_t pid,
-                     uid_t uid, uid_t euid)
+int
+kill_proc_info(int sig, struct siginfo *info, pid_t pid)
+{
+       int error;
+       rcu_read_lock();
+       error = kill_pid_info(sig, info, find_pid(pid));
+       rcu_read_unlock();
+       return error;
+}
+
+/* like kill_pid_info(), but doesn't use uid/euid of "current" */
+int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
+                     uid_t uid, uid_t euid, u32 secid)
 {
        int ret = -EINVAL;
        struct task_struct *p;
@@ -1184,7 +1160,7 @@ int kill_proc_info_as_uid(int sig, struct siginfo *info, pid_t pid,
                return ret;
 
        read_lock(&tasklist_lock);
-       p = find_task_by_pid(pid);
+       p = pid_task(pid, PIDTYPE_PID);
        if (!p) {
                ret = -ESRCH;
                goto out_unlock;
@@ -1195,6 +1171,9 @@ int kill_proc_info_as_uid(int sig, struct siginfo *info, pid_t pid,
                ret = -EPERM;
                goto out_unlock;
        }
+       ret = security_task_kill(p, info, sig, secid);
+       if (ret)
+               goto out_unlock;
        if (sig && p->sighand) {
                unsigned long flags;
                spin_lock_irqsave(&p->sighand->siglock, flags);
@@ -1205,7 +1184,7 @@ out_unlock:
        read_unlock(&tasklist_lock);
        return ret;
 }
-EXPORT_SYMBOL_GPL(kill_proc_info_as_uid);
+EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
 
 /*
  * kill_something_info() interprets pid in interesting ways just like kill(2).
@@ -1216,8 +1195,10 @@ EXPORT_SYMBOL_GPL(kill_proc_info_as_uid);
 
 static int kill_something_info(int sig, struct siginfo *info, int pid)
 {
+       int ret;
+       rcu_read_lock();
        if (!pid) {
-               return kill_pg_info(sig, info, process_group(current));
+               ret = kill_pgrp_info(sig, info, task_pgrp(current));
        } else if (pid == -1) {
                int retval = 0, count = 0;
                struct task_struct * p;
@@ -1232,12 +1213,14 @@ static int kill_something_info(int sig, struct siginfo *info, int pid)
                        }
                }
                read_unlock(&tasklist_lock);
-               return count ? retval : -ESRCH;
+               ret = count ? retval : -ESRCH;
        } else if (pid < 0) {
-               return kill_pg_info(sig, info, -pid);
+               ret = kill_pgrp_info(sig, info, find_pid(-pid));
        } else {
-               return kill_proc_info(sig, info, pid);
+               ret = kill_pid_info(sig, info, find_pid(pid));
        }
+       rcu_read_unlock();
+       return ret;
 }
 
 /*
@@ -1323,11 +1306,17 @@ force_sigsegv(int sig, struct task_struct *p)
        return 0;
 }
 
-int
-kill_pg(pid_t pgrp, int sig, int priv)
+int kill_pgrp(struct pid *pid, int sig, int priv)
+{
+       return kill_pgrp_info(sig, __si_special(priv), pid);
+}
+EXPORT_SYMBOL(kill_pgrp);
+
+int kill_pid(struct pid *pid, int sig, int priv)
 {
-       return kill_pg_info(sig, __si_special(priv), pgrp);
+       return kill_pid_info(sig, __si_special(priv), pid);
 }
+EXPORT_SYMBOL(kill_pid);
 
 int
 kill_proc(pid_t pid, int sig, int priv)
@@ -1375,12 +1364,10 @@ void sigqueue_free(struct sigqueue *q)
        __sigqueue_free(q);
 }
 
-int
-send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
+int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
 {
        unsigned long flags;
        int ret = 0;
-       struct sighand_struct *sh;
 
        BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
 
@@ -1394,48 +1381,17 @@ send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
         */
        rcu_read_lock();
 
-       if (unlikely(p->flags & PF_EXITING)) {
+       if (!likely(lock_task_sighand(p, &flags))) {
                ret = -1;
                goto out_err;
        }
 
-retry:
-       sh = rcu_dereference(p->sighand);
-
-       spin_lock_irqsave(&sh->siglock, flags);
-       if (p->sighand != sh) {
-               /* We raced with exec() in a multithreaded process... */
-               spin_unlock_irqrestore(&sh->siglock, flags);
-               goto retry;
-       }
-
-       /*
-        * We do the check here again to handle the following scenario:
-        *
-        * CPU 0                CPU 1
-        * send_sigqueue
-        * check PF_EXITING
-        * interrupt            exit code running
-        *                      __exit_signal
-        *                      lock sighand->siglock
-        *                      unlock sighand->siglock
-        * lock sh->siglock
-        * add(tsk->pending)    flush_sigqueue(tsk->pending)
-        *
-        */
-
-       if (unlikely(p->flags & PF_EXITING)) {
-               ret = -1;
-               goto out;
-       }
-
        if (unlikely(!list_empty(&q->list))) {
                /*
                 * If an SI_TIMER entry is already queue just increment
                 * the overrun count.
                 */
-               if (q->info.si_code != SI_TIMER)
-                       BUG();
+               BUG_ON(q->info.si_code != SI_TIMER);
                q->info.si_overrun++;
                goto out;
        }
@@ -1451,7 +1407,7 @@ retry:
                signal_wake_up(p, sig == SIGKILL);
 
 out:
-       spin_unlock_irqrestore(&sh->siglock, flags);
+       unlock_task_sighand(p, &flags);
 out_err:
        rcu_read_unlock();
 
@@ -1483,8 +1439,7 @@ send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
                 * the overrun count.  Other uses should not try to
                 * send the signal multiple times.
                 */
-               if (q->info.si_code != SI_TIMER)
-                       BUG();
+               BUG_ON(q->info.si_code != SI_TIMER);
                q->info.si_overrun++;
                goto out;
        } 
@@ -1583,14 +1538,14 @@ void do_notify_parent(struct task_struct *tsk, int sig)
        spin_unlock_irqrestore(&psig->siglock, flags);
 }
 
-static void do_notify_parent_cldstop(struct task_struct *tsk, int to_self, int why)
+static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
 {
        struct siginfo info;
        unsigned long flags;
        struct task_struct *parent;
        struct sighand_struct *sighand;
 
-       if (to_self)
+       if (tsk->ptrace & PT_PTRACED)
                parent = tsk->parent;
        else {
                tsk = tsk->group_leader;
@@ -1633,6 +1588,35 @@ static void do_notify_parent_cldstop(struct task_struct *tsk, int to_self, int w
        spin_unlock_irqrestore(&sighand->siglock, flags);
 }
 
+static inline int may_ptrace_stop(void)
+{
+       if (!likely(current->ptrace & PT_PTRACED))
+               return 0;
+
+       if (unlikely(current->parent == current->real_parent &&
+                   (current->ptrace & PT_ATTACHED)))
+               return 0;
+
+       if (unlikely(current->signal == current->parent->signal) &&
+           unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))
+               return 0;
+
+       /*
+        * Are we in the middle of do_coredump?
+        * If so and our tracer is also part of the coredump stopping
+        * is a deadlock situation, and pointless because our tracer
+        * is dead so don't allow us to stop.
+        * If SIGKILL was already sent before the caller unlocked
+        * ->siglock we must see ->core_waiters != 0. Otherwise it
+        * is safe to enter schedule().
+        */
+       if (unlikely(current->mm->core_waiters) &&
+           unlikely(current->mm == current->parent->mm))
+               return 0;
+
+       return 1;
+}
+
 /*
  * This must be called with current->sighand->siglock held.
  *
@@ -1659,13 +1643,10 @@ static void ptrace_stop(int exit_code, int nostop_code, siginfo_t *info)
        /* Let the debugger run.  */
        set_current_state(TASK_TRACED);
        spin_unlock_irq(&current->sighand->siglock);
+       try_to_freeze();
        read_lock(&tasklist_lock);
-       if (likely(current->ptrace & PT_PTRACED) &&
-           likely(current->parent != current->real_parent ||
-                  !(current->ptrace & PT_ATTACHED)) &&
-           (likely(current->parent->signal != current->signal) ||
-            !unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))) {
-               do_notify_parent_cldstop(current, 1, CLD_TRAPPED);
+       if (may_ptrace_stop()) {
+               do_notify_parent_cldstop(current, CLD_TRAPPED);
                read_unlock(&tasklist_lock);
                schedule();
        } else {
@@ -1714,26 +1695,20 @@ void ptrace_notify(int exit_code)
 static void
 finish_stop(int stop_count)
 {
-       int to_self;
-
        /*
         * If there are no other threads in the group, or if there is
         * a group stop in progress and we are the last to stop,
         * report to the parent.  When ptraced, every thread reports itself.
         */
-       if (stop_count < 0 || (current->ptrace & PT_PTRACED))
-               to_self = 1;
-       else if (stop_count == 0)
-               to_self = 0;
-       else
-               goto out;
-
-       read_lock(&tasklist_lock);
-       do_notify_parent_cldstop(current, to_self, CLD_STOPPED);
-       read_unlock(&tasklist_lock);
+       if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
+               read_lock(&tasklist_lock);
+               do_notify_parent_cldstop(current, CLD_STOPPED);
+               read_unlock(&tasklist_lock);
+       }
 
-out:
-       schedule();
+       do {
+               schedule();
+       } while (try_to_freeze());
        /*
         * Now we don't run again until continued.
         */
@@ -1746,12 +1721,10 @@ out:
  * Returns nonzero if we've actually stopped and released the siglock.
  * Returns zero if we didn't stop and still hold the siglock.
  */
-static int
-do_signal_stop(int signr)
+static int do_signal_stop(int signr)
 {
        struct signal_struct *sig = current->signal;
-       struct sighand_struct *sighand = current->sighand;
-       int stop_count = -1;
+       int stop_count;
 
        if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED))
                return 0;
@@ -1761,86 +1734,37 @@ do_signal_stop(int signr)
                 * There is a group stop in progress.  We don't need to
                 * start another one.
                 */
-               signr = sig->group_exit_code;
                stop_count = --sig->group_stop_count;
-               current->exit_code = signr;
-               set_current_state(TASK_STOPPED);
-               if (stop_count == 0)
-                       sig->flags = SIGNAL_STOP_STOPPED;
-               spin_unlock_irq(&sighand->siglock);
-       }
-       else if (thread_group_empty(current)) {
-               /*
-                * Lock must be held through transition to stopped state.
-                */
-               current->exit_code = current->signal->group_exit_code = signr;
-               set_current_state(TASK_STOPPED);
-               sig->flags = SIGNAL_STOP_STOPPED;
-               spin_unlock_irq(&sighand->siglock);
-       }
-       else {
+       } else {
                /*
                 * There is no group stop already in progress.
-                * We must initiate one now, but that requires
-                * dropping siglock to get both the tasklist lock
-                * and siglock again in the proper order.  Note that
-                * this allows an intervening SIGCONT to be posted.
-                * We need to check for that and bail out if necessary.
+                * We must initiate one now.
                 */
                struct task_struct *t;
 
-               spin_unlock_irq(&sighand->siglock);
-
-               /* signals can be posted during this window */
-
-               read_lock(&tasklist_lock);
-               spin_lock_irq(&sighand->siglock);
+               sig->group_exit_code = signr;
 
-               if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED)) {
+               stop_count = 0;
+               for (t = next_thread(current); t != current; t = next_thread(t))
                        /*
-                        * Another stop or continue happened while we
-                        * didn't have the lock.  We can just swallow this
-                        * signal now.  If we raced with a SIGCONT, that
-                        * should have just cleared it now.  If we raced
-                        * with another processor delivering a stop signal,
-                        * then the SIGCONT that wakes us up should clear it.
+                        * Setting state to TASK_STOPPED for a group
+                        * stop is always done with the siglock held,
+                        * so this check has no races.
                         */
-                       read_unlock(&tasklist_lock);
-                       return 0;
-               }
-
-               if (sig->group_stop_count == 0) {
-                       sig->group_exit_code = signr;
-                       stop_count = 0;
-                       for (t = next_thread(current); t != current;
-                            t = next_thread(t))
-                               /*
-                                * Setting state to TASK_STOPPED for a group
-                                * stop is always done with the siglock held,
-                                * so this check has no races.
-                                */
-                               if (!t->exit_state &&
-                                   !(t->state & (TASK_STOPPED|TASK_TRACED))) {
-                                       stop_count++;
-                                       signal_wake_up(t, 0);
-                               }
-                       sig->group_stop_count = stop_count;
-               }
-               else {
-                       /* A race with another thread while unlocked.  */
-                       signr = sig->group_exit_code;
-                       stop_count = --sig->group_stop_count;
-               }
-
-               current->exit_code = signr;
-               set_current_state(TASK_STOPPED);
-               if (stop_count == 0)
-                       sig->flags = SIGNAL_STOP_STOPPED;
-
-               spin_unlock_irq(&sighand->siglock);
-               read_unlock(&tasklist_lock);
+                       if (!t->exit_state &&
+                           !(t->state & (TASK_STOPPED|TASK_TRACED))) {
+                               stop_count++;
+                               signal_wake_up(t, 0);
+                       }
+               sig->group_stop_count = stop_count;
        }
 
+       if (stop_count == 0)
+               sig->flags = SIGNAL_STOP_STOPPED;
+       current->exit_code = sig->group_exit_code;
+       __set_current_state(TASK_STOPPED);
+
+       spin_unlock_irq(&current->sighand->siglock);
        finish_stop(stop_count);
        return 1;
 }
@@ -1914,9 +1838,9 @@ relock:
                        /* Let the debugger run.  */
                        ptrace_stop(signr, signr, info);
 
-                       /* We're back.  Did the debugger cancel the sig or group_exit? */
+                       /* We're back.  Did the debugger cancel the sig?  */
                        signr = current->exit_code;
-                       if (signr == 0 || current->signal->flags & SIGNAL_GROUP_EXIT)
+                       if (signr == 0)
                                continue;
 
                        current->exit_code = 0;
@@ -1959,8 +1883,12 @@ relock:
                if (sig_kernel_ignore(signr)) /* Default is nothing. */
                        continue;
 
-               /* Init gets no signals it doesn't want.  */
-               if (current == child_reaper)
+               /*
+                * Init of a pid space gets no signals it doesn't want from
+                * within that pid space. It can of course get signals from
+                * its parent pid space.
+                */
+               if (current == child_reaper(current))
                        continue;
 
                if (sig_kernel_stop(signr)) {
@@ -1979,7 +1907,7 @@ relock:
 
                                /* signals can be posted during this window */
 
-                               if (is_orphaned_pgrp(process_group(current)))
+                               if (is_current_pgrp_orphaned())
                                        goto relock;
 
                                spin_lock_irq(&current->sighand->siglock);
@@ -2029,7 +1957,6 @@ EXPORT_SYMBOL(recalc_sigpending);
 EXPORT_SYMBOL_GPL(dequeue_signal);
 EXPORT_SYMBOL(flush_signals);
 EXPORT_SYMBOL(force_sig);
-EXPORT_SYMBOL(kill_pg);
 EXPORT_SYMBOL(kill_proc);
 EXPORT_SYMBOL(ptrace_notify);
 EXPORT_SYMBOL(send_sig);
@@ -2356,7 +2283,7 @@ static int do_tkill(int tgid, int pid, int sig)
  *  @pid: the PID of the thread
  *  @sig: signal to be sent
  *
- *  This syscall also checks the tgid and returns -ESRCH even if the PID
+ *  This syscall also checks the @tgid and returns -ESRCH even if the PID
  *  exists but it's not belonging to the target process anymore. This
  *  method solves the problem of threads exiting and PIDs getting reused.
  */
@@ -2400,8 +2327,7 @@ sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
        return kill_proc_info(sig, &info, pid);
 }
 
-int
-do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
+int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
 {
        struct k_sigaction *k;
        sigset_t mask;
@@ -2427,6 +2353,7 @@ do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
        if (act) {
                sigdelsetmask(&act->sa.sa_mask,
                              sigmask(SIGKILL) | sigmask(SIGSTOP));
+               *k = *act;
                /*
                 * POSIX 3.3.1.3:
                 *  "Setting a signal action to SIG_IGN for a signal that is
@@ -2439,19 +2366,8 @@ do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
                 *   be discarded, whether or not it is blocked"
                 */
                if (act->sa.sa_handler == SIG_IGN ||
-                   (act->sa.sa_handler == SIG_DFL &&
-                    sig_kernel_ignore(sig))) {
-                       /*
-                        * This is a fairly rare case, so we only take the
-                        * tasklist_lock once we're sure we'll need it.
-                        * Now we must do this little unlock and relock
-                        * dance to maintain the lock hierarchy.
-                        */
+                  (act->sa.sa_handler == SIG_DFL && sig_kernel_ignore(sig))) {
                        struct task_struct *t = current;
-                       spin_unlock_irq(&t->sighand->siglock);
-                       read_lock(&tasklist_lock);
-                       spin_lock_irq(&t->sighand->siglock);
-                       *k = *act;
                        sigemptyset(&mask);
                        sigaddset(&mask, sig);
                        rm_from_queue_full(&mask, &t->signal->shared_pending);
@@ -2460,12 +2376,7 @@ do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
                                recalc_sigpending_tsk(t);
                                t = next_thread(t);
                        } while (t != current);
-                       spin_unlock_irq(&current->sighand->siglock);
-                       read_unlock(&tasklist_lock);
-                       return 0;
                }
-
-               *k = *act;
        }
 
        spin_unlock_irq(&current->sighand->siglock);
@@ -2717,11 +2628,12 @@ asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
 }
 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
 
+__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
+{
+       return NULL;
+}
+
 void __init signals_init(void)
 {
-       sigqueue_cachep =
-               kmem_cache_create("sigqueue",
-                                 sizeof(struct sigqueue),
-                                 __alignof__(struct sigqueue),
-                                 SLAB_PANIC, NULL, NULL);
+       sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
 }