1 files changed, 73 insertions, 48 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index c49bd193b058..b3f7a1bb5e55 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -84,7 +84,7 @@ static kmem_cache_t *task_struct_cachep;
 #endif
 
 /* SLAB cache for signal_struct structures (tsk->signal) */
-kmem_cache_t *signal_cachep;
+static kmem_cache_t *signal_cachep;
 
 /* SLAB cache for sighand_struct structures (tsk->sighand) */
 kmem_cache_t *sighand_cachep;
@@ -786,14 +786,6 @@ int unshare_files(void)
 
 EXPORT_SYMBOL(unshare_files);
 
-void sighand_free_cb(struct rcu_head *rhp)
-{
-        struct sighand_struct *sp;
-
-        sp = container_of(rhp, struct sighand_struct, rcu);
-        kmem_cache_free(sighand_cachep, sp);
-}
-
 static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
 {
         struct sighand_struct *sig;
@@ -806,12 +798,17 @@ static inline int copy_sighand(unsigned long clone_flags, struct task_struct * t
         rcu_assign_pointer(tsk->sighand, sig);
         if (!sig)
                 return -ENOMEM;
-        spin_lock_init(&sig->siglock);
         atomic_set(&sig->count, 1);
         memcpy(sig->action, current->sighand->action, sizeof(sig->action));
         return 0;
 }
 
+void __cleanup_sighand(struct sighand_struct *sighand)
+{
+        if (atomic_dec_and_test(&sighand->count))
+                kmem_cache_free(sighand_cachep, sighand);
+}
+
 static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk)
 {
         struct signal_struct *sig;
@@ -881,6 +878,22 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts
         return 0;
 }
 
+void __cleanup_signal(struct signal_struct *sig)
+{
+        exit_thread_group_keys(sig);
+        kmem_cache_free(signal_cachep, sig);
+}
+
+static inline void cleanup_signal(struct task_struct *tsk)
+{
+        struct signal_struct *sig = tsk->signal;
+
+        atomic_dec(&sig->live);
+
+        if (atomic_dec_and_test(&sig->count))
+                __cleanup_signal(sig);
+}
+
 static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
 {
         unsigned long new_flags = p->flags;
@@ -1095,6 +1108,7 @@ static task_t *copy_process(unsigned long clone_flags,
          * We dont wake it up yet.
          */
         p->group_leader = p;
+        INIT_LIST_HEAD(&p->thread_group);
         INIT_LIST_HEAD(&p->ptrace_children);
         INIT_LIST_HEAD(&p->ptrace_list);
 
@@ -1118,16 +1132,6 @@ static task_t *copy_process(unsigned long clone_flags,
                         !cpu_online(task_cpu(p))))
                 set_task_cpu(p, smp_processor_id());
 
-        /*
-         * Check for pending SIGKILL! The new thread should not be allowed
-         * to slip out of an OOM kill. (or normal SIGKILL.)
-         */
-        if (sigismember(&current->pending.signal, SIGKILL)) {
-                write_unlock_irq(&tasklist_lock);
-                retval = -EINTR;
-                goto bad_fork_cleanup_namespace;
-        }
-
         /* CLONE_PARENT re-uses the old parent */
         if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
                 p->real_parent = current->real_parent;
@@ -1136,6 +1140,23 @@ static task_t *copy_process(unsigned long clone_flags,
         p->parent = p->real_parent;
 
         spin_lock(&current->sighand->siglock);
+
+        /*
+         * Process group and session signals need to be delivered to just the
+         * parent before the fork or both the parent and the child after the
+         * fork. Restart if a signal comes in before we add the new process to
+         * it's process group.
+         * A fatal signal pending means that current will exit, so the new
+         * thread can't slip out of an OOM kill (or normal SIGKILL).
+         */
+        recalc_sigpending();
+        if (signal_pending(current)) {
+                spin_unlock(&current->sighand->siglock);
+                write_unlock_irq(&tasklist_lock);
+                retval = -ERESTARTNOINTR;
+                goto bad_fork_cleanup_namespace;
+        }
+
         if (clone_flags & CLONE_THREAD) {
                 /*
                  * Important: if an exit-all has been started then
@@ -1148,17 +1169,9 @@ static task_t *copy_process(unsigned long clone_flags,
                         retval = -EAGAIN;
                         goto bad_fork_cleanup_namespace;
                 }
-                p->group_leader = current->group_leader;
 
-                if (current->signal->group_stop_count > 0) {
-                        /*
-                         * There is an all-stop in progress for the group.
-                         * We ourselves will stop as soon as we check signals.
-                         * Make the new thread part of that group stop too.
-                         */
-                        current->signal->group_stop_count++;
-                        set_tsk_thread_flag(p, TIF_SIGPENDING);
-                }
+                p->group_leader = current->group_leader;
+                list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
 
                 if (!cputime_eq(current->signal->it_virt_expires,
                                 cputime_zero) ||
@@ -1181,23 +1194,25 @@ static task_t *copy_process(unsigned long clone_flags,
          */
         p->ioprio = current->ioprio;
 
-        SET_LINKS(p);
-        if (unlikely(p->ptrace & PT_PTRACED))
-                __ptrace_link(p, current->parent);
-
-        if (thread_group_leader(p)) {
-                p->signal->tty = current->signal->tty;
-                p->signal->pgrp = process_group(current);
-                p->signal->session = current->signal->session;
-                attach_pid(p, PIDTYPE_PGID, process_group(p));
-                attach_pid(p, PIDTYPE_SID, p->signal->session);
-                if (p->pid)
+        if (likely(p->pid)) {
+                add_parent(p);
+                if (unlikely(p->ptrace & PT_PTRACED))
+                        __ptrace_link(p, current->parent);
+
+                if (thread_group_leader(p)) {
+                        p->signal->tty = current->signal->tty;
+                        p->signal->pgrp = process_group(current);
+                        p->signal->session = current->signal->session;
+                        attach_pid(p, PIDTYPE_PGID, process_group(p));
+                        attach_pid(p, PIDTYPE_SID, p->signal->session);
+
+                        list_add_tail(&p->tasks, &init_task.tasks);
                         __get_cpu_var(process_counts)++;
+                }
+                attach_pid(p, PIDTYPE_PID, p->pid);
+                nr_threads++;
         }
-        attach_pid(p, PIDTYPE_TGID, p->tgid);
-        attach_pid(p, PIDTYPE_PID, p->pid);
 
-        nr_threads++;
         total_forks++;
         spin_unlock(&current->sighand->siglock);
         write_unlock_irq(&tasklist_lock);
@@ -1212,9 +1227,9 @@ bad_fork_cleanup_mm:
         if (p->mm)
                 mmput(p->mm);
 bad_fork_cleanup_signal:
-        exit_signal(p);
+        cleanup_signal(p);
 bad_fork_cleanup_sighand:
-        exit_sighand(p);
+        __cleanup_sighand(p->sighand);
 bad_fork_cleanup_fs:
         exit_fs(p); /* blocking */
 bad_fork_cleanup_files:
@@ -1261,7 +1276,7 @@ task_t * __devinit fork_idle(int cpu)
         if (!task)
                 return ERR_PTR(-ENOMEM);
         init_idle(task, cpu);
-        unhash_process(task);
+
         return task;
 }
 
@@ -1353,11 +1368,21 @@ long do_fork(unsigned long clone_flags,
 #define ARCH_MIN_MMSTRUCT_ALIGN 0
 #endif
 
+static void sighand_ctor(void *data, kmem_cache_t *cachep, unsigned long flags)
+{
+        struct sighand_struct *sighand = data;
+
+        if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
+                                        SLAB_CTOR_CONSTRUCTOR)
+                spin_lock_init(&sighand->siglock);
+}
+
 void __init proc_caches_init(void)
 {
         sighand_cachep = kmem_cache_create("sighand_cache",
                         sizeof(struct sighand_struct), 0,
-                        SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+                        SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU,
+                        sighand_ctor, NULL);
         signal_cachep = kmem_cache_create("signal_cache",
                         sizeof(struct signal_struct), 0,
                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);