1 files changed, 31 insertions, 20 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 4d57d9e3a6e9..b6cce14ba047 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -165,6 +165,18 @@ void free_task(struct task_struct *tsk)
 }
 EXPORT_SYMBOL(free_task);
 
+static inline void free_signal_struct(struct signal_struct *sig)
+{
+        taskstats_tgid_free(sig);
+        kmem_cache_free(signal_cachep, sig);
+}
+
+static inline void put_signal_struct(struct signal_struct *sig)
+{
+        if (atomic_dec_and_test(&sig->sigcnt))
+                free_signal_struct(sig);
+}
+
 void __put_task_struct(struct task_struct *tsk)
 {
         WARN_ON(!tsk->exit_state);
@@ -173,6 +185,7 @@ void __put_task_struct(struct task_struct *tsk)
 
         exit_creds(tsk);
         delayacct_tsk_free(tsk);
+        put_signal_struct(tsk->signal);
 
         if (!profile_handoff_task(tsk))
                 free_task(tsk);
@@ -864,8 +877,9 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
         if (!sig)
                 return -ENOMEM;
 
-        atomic_set(&sig->count, 1);
+        sig->nr_threads = 1;
         atomic_set(&sig->live, 1);
+        atomic_set(&sig->sigcnt, 1);
         init_waitqueue_head(&sig->wait_chldexit);
         if (clone_flags & CLONE_NEWPID)
                 sig->flags |= SIGNAL_UNKILLABLE;
@@ -889,13 +903,6 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
         return 0;
 }
 
-void __cleanup_signal(struct signal_struct *sig)
-{
-        thread_group_cputime_free(sig);
-        tty_kref_put(sig->tty);
-        kmem_cache_free(signal_cachep, sig);
-}
-
 static void copy_flags(unsigned long clone_flags, struct task_struct *p)
 {
         unsigned long new_flags = p->flags;
@@ -1245,8 +1252,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         }
 
         if (clone_flags & CLONE_THREAD) {
-                atomic_inc(&current->signal->count);
+                current->signal->nr_threads++;
                 atomic_inc(&current->signal->live);
+                atomic_inc(&current->signal->sigcnt);
                 p->group_leader = current->group_leader;
                 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
         }
@@ -1259,7 +1267,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                                 p->nsproxy->pid_ns->child_reaper = p;
 
                         p->signal->leader_pid = pid;
-                        tty_kref_put(p->signal->tty);
                         p->signal->tty = tty_kref_get(current->signal->tty);
                         attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
                         attach_pid(p, PIDTYPE_SID, task_session(current));
@@ -1292,7 +1299,7 @@ bad_fork_cleanup_mm:
                 mmput(p->mm);
 bad_fork_cleanup_signal:
         if (!(clone_flags & CLONE_THREAD))
-                __cleanup_signal(p->signal);
+                free_signal_struct(p->signal);
 bad_fork_cleanup_sighand:
         __cleanup_sighand(p->sighand);
 bad_fork_cleanup_fs:
@@ -1327,6 +1334,16 @@ noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_re
         return regs;
 }
 
+static inline void init_idle_pids(struct pid_link *links)
+{
+        enum pid_type type;
+
+        for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
+                INIT_HLIST_NODE(&links[type].node); /* not really needed */
+                links[type].pid = &init_struct_pid;
+        }
+}
+
 struct task_struct * __cpuinit fork_idle(int cpu)
 {
         struct task_struct *task;
@@ -1334,8 +1351,10 @@ struct task_struct * __cpuinit fork_idle(int cpu)
 
         task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL,
                             &init_struct_pid, 0);
-        if (!IS_ERR(task))
+        if (!IS_ERR(task)) {
+                init_idle_pids(task->pids);
                 init_idle(task, cpu);
+        }
 
         return task;
 }
@@ -1507,14 +1526,6 @@ static void check_unshare_flags(unsigned long *flags_ptr)
                 *flags_ptr |= CLONE_SIGHAND;
 
         /*
-         * If unsharing signal handlers and the task was created
-         * using CLONE_THREAD, then must unshare the thread
-         */
-        if ((*flags_ptr & CLONE_SIGHAND) &&
-            (atomic_read(&current->signal->count) > 1))
-                *flags_ptr |= CLONE_THREAD;
-
-        /*
          * If unsharing namespace, must also unshare filesystem information.
          */
         if (*flags_ptr & CLONE_NEWNS)