[PATCH] pid: Implement transfer_pid and use it to simplify de_thread
[safe/jmp/linux-2.6] / kernel / fork.c
index 03975d0..a0dad84 100644 (file)
@@ -11,7 +11,6 @@
  * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
  */
 
-#include <linux/config.h>
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/unistd.h>
@@ -44,6 +43,9 @@
 #include <linux/rmap.h>
 #include <linux/acct.h>
 #include <linux/cn_proc.h>
+#include <linux/delayacct.h>
+#include <linux/taskstats_kern.h>
+#include <linux/random.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -62,9 +64,7 @@ int max_threads;              /* tunable limit on nr_threads */
 
 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
 
- __cacheline_aligned DEFINE_RWLOCK(tasklist_lock);  /* outer */
-
-EXPORT_SYMBOL(tasklist_lock);
+__cacheline_aligned DEFINE_RWLOCK(tasklist_lock);  /* outer */
 
 int nr_processes(void)
 {
@@ -104,6 +104,7 @@ static kmem_cache_t *mm_cachep;
 void free_task(struct task_struct *tsk)
 {
        free_thread_info(tsk->thread_info);
+       rt_mutex_debug_task_free(tsk);
        free_task_struct(tsk);
 }
 EXPORT_SYMBOL(free_task);
@@ -114,22 +115,15 @@ void __put_task_struct(struct task_struct *tsk)
        WARN_ON(atomic_read(&tsk->usage));
        WARN_ON(tsk == current);
 
-       if (unlikely(tsk->audit_context))
-               audit_free(tsk);
        security_task_free(tsk);
        free_uid(tsk->user);
        put_group_info(tsk->group_info);
+       delayacct_tsk_free(tsk);
 
        if (!profile_handoff_task(tsk))
                free_task(tsk);
 }
 
-void __put_task_struct_cb(struct rcu_head *rhp)
-{
-       struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
-       __put_task_struct(tsk);
-}
-
 void __init fork_init(unsigned long mempages)
 {
 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
@@ -182,10 +176,15 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
        tsk->thread_info = ti;
        setup_thread_stack(tsk, orig);
 
+#ifdef CONFIG_CC_STACKPROTECTOR
+       tsk->stack_canary = get_random_int();
+#endif
+
        /* One for us, one for whoever does the "release_task()" (usually parent) */
        atomic_set(&tsk->usage,2);
        atomic_set(&tsk->fs_excl, 0);
        tsk->btrace_seq = 0;
+       tsk->splice_pipe = NULL;
        return tsk;
 }
 
@@ -200,7 +199,10 @@ static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
 
        down_write(&oldmm->mmap_sem);
        flush_cache_mm(oldmm);
-       down_write(&mm->mmap_sem);
+       /*
+        * Not linked in yet - no deadlock potential:
+        */
+       down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
 
        mm->locked_vm = 0;
        mm->mmap = NULL;
@@ -375,6 +377,8 @@ void fastcall __mmdrop(struct mm_struct *mm)
  */
 void mmput(struct mm_struct *mm)
 {
+       might_sleep();
+
        if (atomic_dec_and_test(&mm->mm_users)) {
                exit_aio(mm);
                exit_mmap(mm);
@@ -630,6 +634,7 @@ out:
 /*
  * Allocate a new files structure and copy contents from the
  * passed in files structure.
+ * errorp will be valid only when the returned files_struct is NULL.
  */
 static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
 {
@@ -638,6 +643,7 @@ static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
        int open_files, size, i, expand;
        struct fdtable *old_fdt, *new_fdt;
 
+       *errorp = -ENOMEM;
        newf = alloc_files();
        if (!newf)
                goto out;
@@ -725,7 +731,7 @@ out_release:
        free_fdset (new_fdt->open_fds, new_fdt->max_fdset);
        free_fd_array(new_fdt->fd, new_fdt->max_fds);
        kmem_cache_free(files_cachep, newf);
-       goto out;
+       return NULL;
 }
 
 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
@@ -751,7 +757,6 @@ static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
         * break this.
         */
        tsk->files = NULL;
-       error = -ENOMEM;
        newf = dup_fd(oldf, &error);
        if (!newf)
                goto out;
@@ -821,6 +826,7 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts
        if (clone_flags & CLONE_THREAD) {
                atomic_inc(&current->signal->count);
                atomic_inc(&current->signal->live);
+               taskstats_tgid_alloc(current->signal);
                return 0;
        }
        sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
@@ -865,6 +871,7 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts
        INIT_LIST_HEAD(&sig->cpu_timers[0]);
        INIT_LIST_HEAD(&sig->cpu_timers[1]);
        INIT_LIST_HEAD(&sig->cpu_timers[2]);
+       taskstats_tgid_init(sig);
 
        task_lock(current->group_leader);
        memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
@@ -878,6 +885,7 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts
                tsk->it_prof_expires =
                        secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
        }
+       acct_init_pacct(&sig->pacct);
 
        return 0;
 }
@@ -885,6 +893,7 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts
 void __cleanup_signal(struct signal_struct *sig)
 {
        exit_thread_group_keys(sig);
+       taskstats_tgid_free(sig);
        kmem_cache_free(signal_cachep, sig);
 }
 
@@ -916,6 +925,15 @@ asmlinkage long sys_set_tid_address(int __user *tidptr)
        return current->pid;
 }
 
+static inline void rt_mutex_init_task(struct task_struct *p)
+{
+#ifdef CONFIG_RT_MUTEXES
+       spin_lock_init(&p->pi_lock);
+       plist_head_init(&p->pi_waiters, &p->pi_lock);
+       p->pi_blocked_on = NULL;
+#endif
+}
+
 /*
  * This creates a new process as a copy of the old one,
  * but does not actually start it yet.
@@ -924,13 +942,13 @@ asmlinkage long sys_set_tid_address(int __user *tidptr)
  * parts of the process environment (as per the clone
  * flags). The actual kick-off is left to the caller.
  */
-static task_t *copy_process(unsigned long clone_flags,
-                                unsigned long stack_start,
-                                struct pt_regs *regs,
-                                unsigned long stack_size,
-                                int __user *parent_tidptr,
-                                int __user *child_tidptr,
-                                int pid)
+static struct task_struct *copy_process(unsigned long clone_flags,
+                                       unsigned long stack_start,
+                                       struct pt_regs *regs,
+                                       unsigned long stack_size,
+                                       int __user *parent_tidptr,
+                                       int __user *child_tidptr,
+                                       int pid)
 {
        int retval;
        struct task_struct *p = NULL;
@@ -962,6 +980,10 @@ static task_t *copy_process(unsigned long clone_flags,
        if (!p)
                goto fork_out;
 
+#ifdef CONFIG_TRACE_IRQFLAGS
+       DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
+       DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
+#endif
        retval = -EAGAIN;
        if (atomic_read(&p->user->processes) >=
                        p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
@@ -989,20 +1011,18 @@ static task_t *copy_process(unsigned long clone_flags,
                goto bad_fork_cleanup_put_domain;
 
        p->did_exec = 0;
+       delayacct_tsk_init(p);  /* Must remain after dup_task_struct() */
        copy_flags(clone_flags, p);
        p->pid = pid;
        retval = -EFAULT;
        if (clone_flags & CLONE_PARENT_SETTID)
                if (put_user(p->pid, parent_tidptr))
-                       goto bad_fork_cleanup;
-
-       p->proc_dentry = NULL;
+                       goto bad_fork_cleanup_delays_binfmt;
 
        INIT_LIST_HEAD(&p->children);
        INIT_LIST_HEAD(&p->sibling);
        p->vfork_done = NULL;
        spin_lock_init(&p->alloc_lock);
-       spin_lock_init(&p->proc_lock);
 
        clear_tsk_thread_flag(p, TIF_SIGPENDING);
        init_sigpending(&p->pending);
@@ -1039,6 +1059,28 @@ static task_t *copy_process(unsigned long clone_flags,
        }
        mpol_fix_fork_child_flag(p);
 #endif
+#ifdef CONFIG_TRACE_IRQFLAGS
+       p->irq_events = 0;
+       p->hardirqs_enabled = 0;
+       p->hardirq_enable_ip = 0;
+       p->hardirq_enable_event = 0;
+       p->hardirq_disable_ip = _THIS_IP_;
+       p->hardirq_disable_event = 0;
+       p->softirqs_enabled = 1;
+       p->softirq_enable_ip = _THIS_IP_;
+       p->softirq_enable_event = 0;
+       p->softirq_disable_ip = 0;
+       p->softirq_disable_event = 0;
+       p->hardirq_context = 0;
+       p->softirq_context = 0;
+#endif
+#ifdef CONFIG_LOCKDEP
+       p->lockdep_depth = 0; /* no locks held yet */
+       p->curr_chain_key = 0;
+       p->lockdep_recursion = 0;
+#endif
+
+       rt_mutex_init_task(p);
 
 #ifdef CONFIG_DEBUG_MUTEXES
        p->blocked_on = NULL; /* not blocked yet */
@@ -1082,6 +1124,9 @@ static task_t *copy_process(unsigned long clone_flags,
 #ifdef CONFIG_COMPAT
        p->compat_robust_list = NULL;
 #endif
+       INIT_LIST_HEAD(&p->pi_state_list);
+       p->pi_state_cache = NULL;
+
        /*
         * sigaltstack should be cleared when sharing the same VM
         */
@@ -1162,18 +1207,6 @@ static task_t *copy_process(unsigned long clone_flags,
        }
 
        if (clone_flags & CLONE_THREAD) {
-               /*
-                * Important: if an exit-all has been started then
-                * do not create this new thread - the whole thread
-                * group is supposed to exit anyway.
-                */
-               if (current->signal->flags & SIGNAL_GROUP_EXIT) {
-                       spin_unlock(&current->sighand->siglock);
-                       write_unlock_irq(&tasklist_lock);
-                       retval = -EAGAIN;
-                       goto bad_fork_cleanup_namespace;
-               }
-
                p->group_leader = current->group_leader;
                list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
 
@@ -1210,7 +1243,7 @@ static task_t *copy_process(unsigned long clone_flags,
                        attach_pid(p, PIDTYPE_PGID, process_group(p));
                        attach_pid(p, PIDTYPE_SID, p->signal->session);
 
-                       list_add_tail(&p->tasks, &init_task.tasks);
+                       list_add_tail_rcu(&p->tasks, &init_task.tasks);
                        __get_cpu_var(process_counts)++;
                }
                attach_pid(p, PIDTYPE_PID, p->pid);
@@ -1250,7 +1283,8 @@ bad_fork_cleanup_policy:
 bad_fork_cleanup_cpuset:
 #endif
        cpuset_exit(p);
-bad_fork_cleanup:
+bad_fork_cleanup_delays_binfmt:
+       delayacct_tsk_free(p);
        if (p->binfmt)
                module_put(p->binfmt->module);
 bad_fork_cleanup_put_domain:
@@ -1271,9 +1305,9 @@ struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
        return regs;
 }
 
-task_t * __devinit fork_idle(int cpu)
+struct task_struct * __devinit fork_idle(int cpu)
 {
-       task_t *task;
+       struct task_struct *task;
        struct pt_regs regs;
 
        task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL, NULL, 0);
@@ -1360,8 +1394,10 @@ long do_fork(unsigned long clone_flags,
 
                if (clone_flags & CLONE_VFORK) {
                        wait_for_completion(&vfork);
-                       if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
+                       if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) {
+                               current->ptrace_message = nr;
                                ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
+                       }
                }
        } else {
                free_pid(pid);