signals: make task_struct->signal immutable/refcountable

[mv-sheeva.git] / kernel / fork.c

diff --git a/kernel/fork.c b/kernel/fork.c
index b7879ef6e7cdb68c1c5aa8ba54077507aa9d5481..e08e3012cd6b4e1cf90e4b025ec77c17612c247c 100644 (file)
--- 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)
+{
+       thread_group_cputime_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);
@@ -864,6 +877,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
        if (!sig)
                return -ENOMEM;
 
+       atomic_set(&sig->sigcnt, 1);
        atomic_set(&sig->count, 1);
        atomic_set(&sig->live, 1);
        init_waitqueue_head(&sig->wait_chldexit);
@@ -889,12 +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);
-       kmem_cache_free(signal_cachep, sig);
-}
-
 static void copy_flags(unsigned long clone_flags, struct task_struct *p)
 {
        unsigned long new_flags = p->flags;
@@ -1248,6 +1256,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
        }
 
        if (clone_flags & CLONE_THREAD) {
+               atomic_inc(&current->signal->sigcnt);
                atomic_inc(&current->signal->count);
                atomic_inc(&current->signal->live);
                p->group_leader = current->group_leader;
@@ -1294,7 +1303,7 @@ 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: