4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * 'fork.c' contains the help-routines for the 'fork' system call
9 * (see also entry.S and others).
10 * Fork is rather simple, once you get the hang of it, but the memory
11 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
14 #include <linux/slab.h>
15 #include <linux/init.h>
16 #include <linux/unistd.h>
17 #include <linux/module.h>
18 #include <linux/vmalloc.h>
19 #include <linux/completion.h>
20 #include <linux/mnt_namespace.h>
21 #include <linux/personality.h>
22 #include <linux/mempolicy.h>
23 #include <linux/sem.h>
24 #include <linux/file.h>
25 #include <linux/key.h>
26 #include <linux/binfmts.h>
27 #include <linux/mman.h>
29 #include <linux/nsproxy.h>
30 #include <linux/capability.h>
31 #include <linux/cpu.h>
32 #include <linux/cgroup.h>
33 #include <linux/security.h>
34 #include <linux/swap.h>
35 #include <linux/syscalls.h>
36 #include <linux/jiffies.h>
37 #include <linux/futex.h>
38 #include <linux/task_io_accounting_ops.h>
39 #include <linux/rcupdate.h>
40 #include <linux/ptrace.h>
41 #include <linux/mount.h>
42 #include <linux/audit.h>
43 #include <linux/profile.h>
44 #include <linux/rmap.h>
45 #include <linux/acct.h>
46 #include <linux/tsacct_kern.h>
47 #include <linux/cn_proc.h>
48 #include <linux/freezer.h>
49 #include <linux/delayacct.h>
50 #include <linux/taskstats_kern.h>
51 #include <linux/random.h>
52 #include <linux/tty.h>
53 #include <linux/proc_fs.h>
55 #include <asm/pgtable.h>
56 #include <asm/pgalloc.h>
57 #include <asm/uaccess.h>
58 #include <asm/mmu_context.h>
59 #include <asm/cacheflush.h>
60 #include <asm/tlbflush.h>
63 * Protected counters by write_lock_irq(&tasklist_lock)
65 unsigned long total_forks
; /* Handle normal Linux uptimes. */
66 int nr_threads
; /* The idle threads do not count.. */
68 int max_threads
; /* tunable limit on nr_threads */
70 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
72 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
74 int nr_processes(void)
79 for_each_online_cpu(cpu
)
80 total
+= per_cpu(process_counts
, cpu
);
85 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
86 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
87 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
88 static struct kmem_cache
*task_struct_cachep
;
91 /* SLAB cache for signal_struct structures (tsk->signal) */
92 static struct kmem_cache
*signal_cachep
;
94 /* SLAB cache for sighand_struct structures (tsk->sighand) */
95 struct kmem_cache
*sighand_cachep
;
97 /* SLAB cache for files_struct structures (tsk->files) */
98 struct kmem_cache
*files_cachep
;
100 /* SLAB cache for fs_struct structures (tsk->fs) */
101 struct kmem_cache
*fs_cachep
;
103 /* SLAB cache for vm_area_struct structures */
104 struct kmem_cache
*vm_area_cachep
;
106 /* SLAB cache for mm_struct structures (tsk->mm) */
107 static struct kmem_cache
*mm_cachep
;
109 void free_task(struct task_struct
*tsk
)
111 prop_local_destroy_single(&tsk
->dirties
);
112 free_thread_info(tsk
->stack
);
113 rt_mutex_debug_task_free(tsk
);
114 free_task_struct(tsk
);
116 EXPORT_SYMBOL(free_task
);
118 void __put_task_struct(struct task_struct
*tsk
)
120 WARN_ON(!tsk
->exit_state
);
121 WARN_ON(atomic_read(&tsk
->usage
));
122 WARN_ON(tsk
== current
);
124 security_task_free(tsk
);
126 put_group_info(tsk
->group_info
);
127 delayacct_tsk_free(tsk
);
129 if (!profile_handoff_task(tsk
))
133 void __init
fork_init(unsigned long mempages
)
135 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
136 #ifndef ARCH_MIN_TASKALIGN
137 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
139 /* create a slab on which task_structs can be allocated */
141 kmem_cache_create("task_struct", sizeof(struct task_struct
),
142 ARCH_MIN_TASKALIGN
, SLAB_PANIC
, NULL
);
146 * The default maximum number of threads is set to a safe
147 * value: the thread structures can take up at most half
150 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
153 * we need to allow at least 20 threads to boot a system
158 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
159 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
160 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
161 init_task
.signal
->rlim
[RLIMIT_NPROC
];
164 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
166 struct task_struct
*tsk
;
167 struct thread_info
*ti
;
170 prepare_to_copy(orig
);
172 tsk
= alloc_task_struct();
176 ti
= alloc_thread_info(tsk
);
178 free_task_struct(tsk
);
185 err
= prop_local_init_single(&tsk
->dirties
);
187 free_thread_info(ti
);
188 free_task_struct(tsk
);
192 setup_thread_stack(tsk
, orig
);
194 #ifdef CONFIG_CC_STACKPROTECTOR
195 tsk
->stack_canary
= get_random_int();
198 /* One for us, one for whoever does the "release_task()" (usually parent) */
199 atomic_set(&tsk
->usage
,2);
200 atomic_set(&tsk
->fs_excl
, 0);
201 #ifdef CONFIG_BLK_DEV_IO_TRACE
204 tsk
->splice_pipe
= NULL
;
209 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
211 struct vm_area_struct
*mpnt
, *tmp
, **pprev
;
212 struct rb_node
**rb_link
, *rb_parent
;
214 unsigned long charge
;
215 struct mempolicy
*pol
;
217 down_write(&oldmm
->mmap_sem
);
218 flush_cache_dup_mm(oldmm
);
220 * Not linked in yet - no deadlock potential:
222 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
226 mm
->mmap_cache
= NULL
;
227 mm
->free_area_cache
= oldmm
->mmap_base
;
228 mm
->cached_hole_size
= ~0UL;
230 cpus_clear(mm
->cpu_vm_mask
);
232 rb_link
= &mm
->mm_rb
.rb_node
;
236 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
239 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
240 long pages
= vma_pages(mpnt
);
241 mm
->total_vm
-= pages
;
242 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
247 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
248 unsigned int len
= (mpnt
->vm_end
- mpnt
->vm_start
) >> PAGE_SHIFT
;
249 if (security_vm_enough_memory(len
))
253 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
257 pol
= mpol_copy(vma_policy(mpnt
));
258 retval
= PTR_ERR(pol
);
260 goto fail_nomem_policy
;
261 vma_set_policy(tmp
, pol
);
262 tmp
->vm_flags
&= ~VM_LOCKED
;
268 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
270 if (tmp
->vm_flags
& VM_DENYWRITE
)
271 atomic_dec(&inode
->i_writecount
);
273 /* insert tmp into the share list, just after mpnt */
274 spin_lock(&file
->f_mapping
->i_mmap_lock
);
275 tmp
->vm_truncate_count
= mpnt
->vm_truncate_count
;
276 flush_dcache_mmap_lock(file
->f_mapping
);
277 vma_prio_tree_add(tmp
, mpnt
);
278 flush_dcache_mmap_unlock(file
->f_mapping
);
279 spin_unlock(&file
->f_mapping
->i_mmap_lock
);
283 * Link in the new vma and copy the page table entries.
286 pprev
= &tmp
->vm_next
;
288 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
289 rb_link
= &tmp
->vm_rb
.rb_right
;
290 rb_parent
= &tmp
->vm_rb
;
293 retval
= copy_page_range(mm
, oldmm
, mpnt
);
295 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
296 tmp
->vm_ops
->open(tmp
);
301 /* a new mm has just been created */
302 arch_dup_mmap(oldmm
, mm
);
305 up_write(&mm
->mmap_sem
);
307 up_write(&oldmm
->mmap_sem
);
310 kmem_cache_free(vm_area_cachep
, tmp
);
313 vm_unacct_memory(charge
);
317 static inline int mm_alloc_pgd(struct mm_struct
* mm
)
319 mm
->pgd
= pgd_alloc(mm
);
320 if (unlikely(!mm
->pgd
))
325 static inline void mm_free_pgd(struct mm_struct
* mm
)
330 #define dup_mmap(mm, oldmm) (0)
331 #define mm_alloc_pgd(mm) (0)
332 #define mm_free_pgd(mm)
333 #endif /* CONFIG_MMU */
335 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
337 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
338 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
340 #include <linux/init_task.h>
342 static struct mm_struct
* mm_init(struct mm_struct
* mm
)
344 atomic_set(&mm
->mm_users
, 1);
345 atomic_set(&mm
->mm_count
, 1);
346 init_rwsem(&mm
->mmap_sem
);
347 INIT_LIST_HEAD(&mm
->mmlist
);
348 mm
->flags
= (current
->mm
) ? current
->mm
->flags
349 : MMF_DUMP_FILTER_DEFAULT
;
350 mm
->core_waiters
= 0;
352 set_mm_counter(mm
, file_rss
, 0);
353 set_mm_counter(mm
, anon_rss
, 0);
354 spin_lock_init(&mm
->page_table_lock
);
355 rwlock_init(&mm
->ioctx_list_lock
);
356 mm
->ioctx_list
= NULL
;
357 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
358 mm
->cached_hole_size
= ~0UL;
360 if (likely(!mm_alloc_pgd(mm
))) {
369 * Allocate and initialize an mm_struct.
371 struct mm_struct
* mm_alloc(void)
373 struct mm_struct
* mm
;
377 memset(mm
, 0, sizeof(*mm
));
384 * Called when the last reference to the mm
385 * is dropped: either by a lazy thread or by
386 * mmput. Free the page directory and the mm.
388 void fastcall
__mmdrop(struct mm_struct
*mm
)
390 BUG_ON(mm
== &init_mm
);
397 * Decrement the use count and release all resources for an mm.
399 void mmput(struct mm_struct
*mm
)
403 if (atomic_dec_and_test(&mm
->mm_users
)) {
406 if (!list_empty(&mm
->mmlist
)) {
407 spin_lock(&mmlist_lock
);
408 list_del(&mm
->mmlist
);
409 spin_unlock(&mmlist_lock
);
415 EXPORT_SYMBOL_GPL(mmput
);
418 * get_task_mm - acquire a reference to the task's mm
420 * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning
421 * this kernel workthread has transiently adopted a user mm with use_mm,
422 * to do its AIO) is not set and if so returns a reference to it, after
423 * bumping up the use count. User must release the mm via mmput()
424 * after use. Typically used by /proc and ptrace.
426 struct mm_struct
*get_task_mm(struct task_struct
*task
)
428 struct mm_struct
*mm
;
433 if (task
->flags
& PF_BORROWED_MM
)
436 atomic_inc(&mm
->mm_users
);
441 EXPORT_SYMBOL_GPL(get_task_mm
);
443 /* Please note the differences between mmput and mm_release.
444 * mmput is called whenever we stop holding onto a mm_struct,
445 * error success whatever.
447 * mm_release is called after a mm_struct has been removed
448 * from the current process.
450 * This difference is important for error handling, when we
451 * only half set up a mm_struct for a new process and need to restore
452 * the old one. Because we mmput the new mm_struct before
453 * restoring the old one. . .
454 * Eric Biederman 10 January 1998
456 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
458 struct completion
*vfork_done
= tsk
->vfork_done
;
460 /* Get rid of any cached register state */
461 deactivate_mm(tsk
, mm
);
463 /* notify parent sleeping on vfork() */
465 tsk
->vfork_done
= NULL
;
466 complete(vfork_done
);
470 * If we're exiting normally, clear a user-space tid field if
471 * requested. We leave this alone when dying by signal, to leave
472 * the value intact in a core dump, and to save the unnecessary
473 * trouble otherwise. Userland only wants this done for a sys_exit.
475 if (tsk
->clear_child_tid
476 && !(tsk
->flags
& PF_SIGNALED
)
477 && atomic_read(&mm
->mm_users
) > 1) {
478 u32 __user
* tidptr
= tsk
->clear_child_tid
;
479 tsk
->clear_child_tid
= NULL
;
482 * We don't check the error code - if userspace has
483 * not set up a proper pointer then tough luck.
486 sys_futex(tidptr
, FUTEX_WAKE
, 1, NULL
, NULL
, 0);
491 * Allocate a new mm structure and copy contents from the
492 * mm structure of the passed in task structure.
494 static struct mm_struct
*dup_mm(struct task_struct
*tsk
)
496 struct mm_struct
*mm
, *oldmm
= current
->mm
;
506 memcpy(mm
, oldmm
, sizeof(*mm
));
508 /* Initializing for Swap token stuff */
509 mm
->token_priority
= 0;
510 mm
->last_interval
= 0;
515 if (init_new_context(tsk
, mm
))
518 err
= dup_mmap(mm
, oldmm
);
522 mm
->hiwater_rss
= get_mm_rss(mm
);
523 mm
->hiwater_vm
= mm
->total_vm
;
535 * If init_new_context() failed, we cannot use mmput() to free the mm
536 * because it calls destroy_context()
543 static int copy_mm(unsigned long clone_flags
, struct task_struct
* tsk
)
545 struct mm_struct
* mm
, *oldmm
;
548 tsk
->min_flt
= tsk
->maj_flt
= 0;
549 tsk
->nvcsw
= tsk
->nivcsw
= 0;
552 tsk
->active_mm
= NULL
;
555 * Are we cloning a kernel thread?
557 * We need to steal a active VM for that..
563 if (clone_flags
& CLONE_VM
) {
564 atomic_inc(&oldmm
->mm_users
);
575 /* Initializing for Swap token stuff */
576 mm
->token_priority
= 0;
577 mm
->last_interval
= 0;
587 static struct fs_struct
*__copy_fs_struct(struct fs_struct
*old
)
589 struct fs_struct
*fs
= kmem_cache_alloc(fs_cachep
, GFP_KERNEL
);
590 /* We don't need to lock fs - think why ;-) */
592 atomic_set(&fs
->count
, 1);
593 rwlock_init(&fs
->lock
);
594 fs
->umask
= old
->umask
;
595 read_lock(&old
->lock
);
596 fs
->rootmnt
= mntget(old
->rootmnt
);
597 fs
->root
= dget(old
->root
);
598 fs
->pwdmnt
= mntget(old
->pwdmnt
);
599 fs
->pwd
= dget(old
->pwd
);
601 fs
->altrootmnt
= mntget(old
->altrootmnt
);
602 fs
->altroot
= dget(old
->altroot
);
604 fs
->altrootmnt
= NULL
;
607 read_unlock(&old
->lock
);
612 struct fs_struct
*copy_fs_struct(struct fs_struct
*old
)
614 return __copy_fs_struct(old
);
617 EXPORT_SYMBOL_GPL(copy_fs_struct
);
619 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
621 if (clone_flags
& CLONE_FS
) {
622 atomic_inc(¤t
->fs
->count
);
625 tsk
->fs
= __copy_fs_struct(current
->fs
);
631 static int count_open_files(struct fdtable
*fdt
)
633 int size
= fdt
->max_fds
;
636 /* Find the last open fd */
637 for (i
= size
/(8*sizeof(long)); i
> 0; ) {
638 if (fdt
->open_fds
->fds_bits
[--i
])
641 i
= (i
+1) * 8 * sizeof(long);
645 static struct files_struct
*alloc_files(void)
647 struct files_struct
*newf
;
650 newf
= kmem_cache_alloc(files_cachep
, GFP_KERNEL
);
654 atomic_set(&newf
->count
, 1);
656 spin_lock_init(&newf
->file_lock
);
659 fdt
->max_fds
= NR_OPEN_DEFAULT
;
660 fdt
->close_on_exec
= (fd_set
*)&newf
->close_on_exec_init
;
661 fdt
->open_fds
= (fd_set
*)&newf
->open_fds_init
;
662 fdt
->fd
= &newf
->fd_array
[0];
663 INIT_RCU_HEAD(&fdt
->rcu
);
665 rcu_assign_pointer(newf
->fdt
, fdt
);
671 * Allocate a new files structure and copy contents from the
672 * passed in files structure.
673 * errorp will be valid only when the returned files_struct is NULL.
675 static struct files_struct
*dup_fd(struct files_struct
*oldf
, int *errorp
)
677 struct files_struct
*newf
;
678 struct file
**old_fds
, **new_fds
;
679 int open_files
, size
, i
;
680 struct fdtable
*old_fdt
, *new_fdt
;
683 newf
= alloc_files();
687 spin_lock(&oldf
->file_lock
);
688 old_fdt
= files_fdtable(oldf
);
689 new_fdt
= files_fdtable(newf
);
690 open_files
= count_open_files(old_fdt
);
693 * Check whether we need to allocate a larger fd array and fd set.
694 * Note: we're not a clone task, so the open count won't change.
696 if (open_files
> new_fdt
->max_fds
) {
697 new_fdt
->max_fds
= 0;
698 spin_unlock(&oldf
->file_lock
);
699 spin_lock(&newf
->file_lock
);
700 *errorp
= expand_files(newf
, open_files
-1);
701 spin_unlock(&newf
->file_lock
);
704 new_fdt
= files_fdtable(newf
);
706 * Reacquire the oldf lock and a pointer to its fd table
707 * who knows it may have a new bigger fd table. We need
708 * the latest pointer.
710 spin_lock(&oldf
->file_lock
);
711 old_fdt
= files_fdtable(oldf
);
714 old_fds
= old_fdt
->fd
;
715 new_fds
= new_fdt
->fd
;
717 memcpy(new_fdt
->open_fds
->fds_bits
,
718 old_fdt
->open_fds
->fds_bits
, open_files
/8);
719 memcpy(new_fdt
->close_on_exec
->fds_bits
,
720 old_fdt
->close_on_exec
->fds_bits
, open_files
/8);
722 for (i
= open_files
; i
!= 0; i
--) {
723 struct file
*f
= *old_fds
++;
728 * The fd may be claimed in the fd bitmap but not yet
729 * instantiated in the files array if a sibling thread
730 * is partway through open(). So make sure that this
731 * fd is available to the new process.
733 FD_CLR(open_files
- i
, new_fdt
->open_fds
);
735 rcu_assign_pointer(*new_fds
++, f
);
737 spin_unlock(&oldf
->file_lock
);
739 /* compute the remainder to be cleared */
740 size
= (new_fdt
->max_fds
- open_files
) * sizeof(struct file
*);
742 /* This is long word aligned thus could use a optimized version */
743 memset(new_fds
, 0, size
);
745 if (new_fdt
->max_fds
> open_files
) {
746 int left
= (new_fdt
->max_fds
-open_files
)/8;
747 int start
= open_files
/ (8 * sizeof(unsigned long));
749 memset(&new_fdt
->open_fds
->fds_bits
[start
], 0, left
);
750 memset(&new_fdt
->close_on_exec
->fds_bits
[start
], 0, left
);
756 kmem_cache_free(files_cachep
, newf
);
761 static int copy_files(unsigned long clone_flags
, struct task_struct
* tsk
)
763 struct files_struct
*oldf
, *newf
;
767 * A background process may not have any files ...
769 oldf
= current
->files
;
773 if (clone_flags
& CLONE_FILES
) {
774 atomic_inc(&oldf
->count
);
779 * Note: we may be using current for both targets (See exec.c)
780 * This works because we cache current->files (old) as oldf. Don't
784 newf
= dup_fd(oldf
, &error
);
795 * Helper to unshare the files of the current task.
796 * We don't want to expose copy_files internals to
797 * the exec layer of the kernel.
800 int unshare_files(void)
802 struct files_struct
*files
= current
->files
;
807 /* This can race but the race causes us to copy when we don't
808 need to and drop the copy */
809 if(atomic_read(&files
->count
) == 1)
811 atomic_inc(&files
->count
);
814 rc
= copy_files(0, current
);
816 current
->files
= files
;
820 EXPORT_SYMBOL(unshare_files
);
822 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
824 struct sighand_struct
*sig
;
826 if (clone_flags
& (CLONE_SIGHAND
| CLONE_THREAD
)) {
827 atomic_inc(¤t
->sighand
->count
);
830 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
831 rcu_assign_pointer(tsk
->sighand
, sig
);
834 atomic_set(&sig
->count
, 1);
835 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
839 void __cleanup_sighand(struct sighand_struct
*sighand
)
841 if (atomic_dec_and_test(&sighand
->count
))
842 kmem_cache_free(sighand_cachep
, sighand
);
845 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
847 struct signal_struct
*sig
;
850 if (clone_flags
& CLONE_THREAD
) {
851 atomic_inc(¤t
->signal
->count
);
852 atomic_inc(¤t
->signal
->live
);
855 sig
= kmem_cache_alloc(signal_cachep
, GFP_KERNEL
);
860 ret
= copy_thread_group_keys(tsk
);
862 kmem_cache_free(signal_cachep
, sig
);
866 atomic_set(&sig
->count
, 1);
867 atomic_set(&sig
->live
, 1);
868 init_waitqueue_head(&sig
->wait_chldexit
);
870 sig
->group_exit_code
= 0;
871 sig
->group_exit_task
= NULL
;
872 sig
->group_stop_count
= 0;
873 sig
->curr_target
= NULL
;
874 init_sigpending(&sig
->shared_pending
);
875 INIT_LIST_HEAD(&sig
->posix_timers
);
877 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
878 sig
->it_real_incr
.tv64
= 0;
879 sig
->real_timer
.function
= it_real_fn
;
882 sig
->it_virt_expires
= cputime_zero
;
883 sig
->it_virt_incr
= cputime_zero
;
884 sig
->it_prof_expires
= cputime_zero
;
885 sig
->it_prof_incr
= cputime_zero
;
887 sig
->leader
= 0; /* session leadership doesn't inherit */
888 sig
->tty_old_pgrp
= NULL
;
890 sig
->utime
= sig
->stime
= sig
->cutime
= sig
->cstime
= cputime_zero
;
891 sig
->gtime
= cputime_zero
;
892 sig
->cgtime
= cputime_zero
;
893 sig
->nvcsw
= sig
->nivcsw
= sig
->cnvcsw
= sig
->cnivcsw
= 0;
894 sig
->min_flt
= sig
->maj_flt
= sig
->cmin_flt
= sig
->cmaj_flt
= 0;
895 sig
->inblock
= sig
->oublock
= sig
->cinblock
= sig
->coublock
= 0;
896 sig
->sum_sched_runtime
= 0;
897 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
898 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
899 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
900 taskstats_tgid_init(sig
);
902 task_lock(current
->group_leader
);
903 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
904 task_unlock(current
->group_leader
);
906 if (sig
->rlim
[RLIMIT_CPU
].rlim_cur
!= RLIM_INFINITY
) {
908 * New sole thread in the process gets an expiry time
909 * of the whole CPU time limit.
911 tsk
->it_prof_expires
=
912 secs_to_cputime(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
914 acct_init_pacct(&sig
->pacct
);
921 void __cleanup_signal(struct signal_struct
*sig
)
923 exit_thread_group_keys(sig
);
924 kmem_cache_free(signal_cachep
, sig
);
927 static void cleanup_signal(struct task_struct
*tsk
)
929 struct signal_struct
*sig
= tsk
->signal
;
931 atomic_dec(&sig
->live
);
933 if (atomic_dec_and_test(&sig
->count
))
934 __cleanup_signal(sig
);
937 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
939 unsigned long new_flags
= p
->flags
;
941 new_flags
&= ~PF_SUPERPRIV
;
942 new_flags
|= PF_FORKNOEXEC
;
943 if (!(clone_flags
& CLONE_PTRACE
))
945 p
->flags
= new_flags
;
946 clear_freeze_flag(p
);
949 asmlinkage
long sys_set_tid_address(int __user
*tidptr
)
951 current
->clear_child_tid
= tidptr
;
953 return task_pid_vnr(current
);
956 static void rt_mutex_init_task(struct task_struct
*p
)
958 spin_lock_init(&p
->pi_lock
);
959 #ifdef CONFIG_RT_MUTEXES
960 plist_head_init(&p
->pi_waiters
, &p
->pi_lock
);
961 p
->pi_blocked_on
= NULL
;
966 * This creates a new process as a copy of the old one,
967 * but does not actually start it yet.
969 * It copies the registers, and all the appropriate
970 * parts of the process environment (as per the clone
971 * flags). The actual kick-off is left to the caller.
973 static struct task_struct
*copy_process(unsigned long clone_flags
,
974 unsigned long stack_start
,
975 struct pt_regs
*regs
,
976 unsigned long stack_size
,
977 int __user
*child_tidptr
,
981 struct task_struct
*p
;
982 int cgroup_callbacks_done
= 0;
984 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
985 return ERR_PTR(-EINVAL
);
988 * Thread groups must share signals as well, and detached threads
989 * can only be started up within the thread group.
991 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
992 return ERR_PTR(-EINVAL
);
995 * Shared signal handlers imply shared VM. By way of the above,
996 * thread groups also imply shared VM. Blocking this case allows
997 * for various simplifications in other code.
999 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1000 return ERR_PTR(-EINVAL
);
1002 retval
= security_task_create(clone_flags
);
1007 p
= dup_task_struct(current
);
1011 rt_mutex_init_task(p
);
1013 #ifdef CONFIG_TRACE_IRQFLAGS
1014 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1015 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1018 if (atomic_read(&p
->user
->processes
) >=
1019 p
->signal
->rlim
[RLIMIT_NPROC
].rlim_cur
) {
1020 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
1021 p
->user
!= current
->nsproxy
->user_ns
->root_user
)
1025 atomic_inc(&p
->user
->__count
);
1026 atomic_inc(&p
->user
->processes
);
1027 get_group_info(p
->group_info
);
1030 * If multiple threads are within copy_process(), then this check
1031 * triggers too late. This doesn't hurt, the check is only there
1032 * to stop root fork bombs.
1034 if (nr_threads
>= max_threads
)
1035 goto bad_fork_cleanup_count
;
1037 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
1038 goto bad_fork_cleanup_count
;
1040 if (p
->binfmt
&& !try_module_get(p
->binfmt
->module
))
1041 goto bad_fork_cleanup_put_domain
;
1044 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1045 copy_flags(clone_flags
, p
);
1046 INIT_LIST_HEAD(&p
->children
);
1047 INIT_LIST_HEAD(&p
->sibling
);
1048 #ifdef CONFIG_PREEMPT_RCU
1049 p
->rcu_read_lock_nesting
= 0;
1050 p
->rcu_flipctr_idx
= 0;
1051 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1052 p
->vfork_done
= NULL
;
1053 spin_lock_init(&p
->alloc_lock
);
1055 clear_tsk_thread_flag(p
, TIF_SIGPENDING
);
1056 init_sigpending(&p
->pending
);
1058 p
->utime
= cputime_zero
;
1059 p
->stime
= cputime_zero
;
1060 p
->gtime
= cputime_zero
;
1061 p
->utimescaled
= cputime_zero
;
1062 p
->stimescaled
= cputime_zero
;
1063 p
->prev_utime
= cputime_zero
;
1064 p
->prev_stime
= cputime_zero
;
1066 #ifdef CONFIG_DETECT_SOFTLOCKUP
1067 p
->last_switch_count
= 0;
1068 p
->last_switch_timestamp
= 0;
1071 #ifdef CONFIG_TASK_XACCT
1072 p
->rchar
= 0; /* I/O counter: bytes read */
1073 p
->wchar
= 0; /* I/O counter: bytes written */
1074 p
->syscr
= 0; /* I/O counter: read syscalls */
1075 p
->syscw
= 0; /* I/O counter: write syscalls */
1077 task_io_accounting_init(p
);
1078 acct_clear_integrals(p
);
1080 p
->it_virt_expires
= cputime_zero
;
1081 p
->it_prof_expires
= cputime_zero
;
1082 p
->it_sched_expires
= 0;
1083 INIT_LIST_HEAD(&p
->cpu_timers
[0]);
1084 INIT_LIST_HEAD(&p
->cpu_timers
[1]);
1085 INIT_LIST_HEAD(&p
->cpu_timers
[2]);
1087 p
->lock_depth
= -1; /* -1 = no lock */
1088 do_posix_clock_monotonic_gettime(&p
->start_time
);
1089 p
->real_start_time
= p
->start_time
;
1090 monotonic_to_bootbased(&p
->real_start_time
);
1091 #ifdef CONFIG_SECURITY
1094 p
->io_context
= NULL
;
1095 p
->audit_context
= NULL
;
1098 p
->mempolicy
= mpol_copy(p
->mempolicy
);
1099 if (IS_ERR(p
->mempolicy
)) {
1100 retval
= PTR_ERR(p
->mempolicy
);
1101 p
->mempolicy
= NULL
;
1102 goto bad_fork_cleanup_cgroup
;
1104 mpol_fix_fork_child_flag(p
);
1106 #ifdef CONFIG_TRACE_IRQFLAGS
1108 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1109 p
->hardirqs_enabled
= 1;
1111 p
->hardirqs_enabled
= 0;
1113 p
->hardirq_enable_ip
= 0;
1114 p
->hardirq_enable_event
= 0;
1115 p
->hardirq_disable_ip
= _THIS_IP_
;
1116 p
->hardirq_disable_event
= 0;
1117 p
->softirqs_enabled
= 1;
1118 p
->softirq_enable_ip
= _THIS_IP_
;
1119 p
->softirq_enable_event
= 0;
1120 p
->softirq_disable_ip
= 0;
1121 p
->softirq_disable_event
= 0;
1122 p
->hardirq_context
= 0;
1123 p
->softirq_context
= 0;
1125 #ifdef CONFIG_LOCKDEP
1126 p
->lockdep_depth
= 0; /* no locks held yet */
1127 p
->curr_chain_key
= 0;
1128 p
->lockdep_recursion
= 0;
1131 #ifdef CONFIG_DEBUG_MUTEXES
1132 p
->blocked_on
= NULL
; /* not blocked yet */
1135 /* Perform scheduler related setup. Assign this task to a CPU. */
1136 sched_fork(p
, clone_flags
);
1138 if ((retval
= security_task_alloc(p
)))
1139 goto bad_fork_cleanup_policy
;
1140 if ((retval
= audit_alloc(p
)))
1141 goto bad_fork_cleanup_security
;
1142 /* copy all the process information */
1143 if ((retval
= copy_semundo(clone_flags
, p
)))
1144 goto bad_fork_cleanup_audit
;
1145 if ((retval
= copy_files(clone_flags
, p
)))
1146 goto bad_fork_cleanup_semundo
;
1147 if ((retval
= copy_fs(clone_flags
, p
)))
1148 goto bad_fork_cleanup_files
;
1149 if ((retval
= copy_sighand(clone_flags
, p
)))
1150 goto bad_fork_cleanup_fs
;
1151 if ((retval
= copy_signal(clone_flags
, p
)))
1152 goto bad_fork_cleanup_sighand
;
1153 if ((retval
= copy_mm(clone_flags
, p
)))
1154 goto bad_fork_cleanup_signal
;
1155 if ((retval
= copy_keys(clone_flags
, p
)))
1156 goto bad_fork_cleanup_mm
;
1157 if ((retval
= copy_namespaces(clone_flags
, p
)))
1158 goto bad_fork_cleanup_keys
;
1159 retval
= copy_thread(0, clone_flags
, stack_start
, stack_size
, p
, regs
);
1161 goto bad_fork_cleanup_namespaces
;
1163 if (pid
!= &init_struct_pid
) {
1165 pid
= alloc_pid(task_active_pid_ns(p
));
1167 goto bad_fork_cleanup_namespaces
;
1169 if (clone_flags
& CLONE_NEWPID
) {
1170 retval
= pid_ns_prepare_proc(task_active_pid_ns(p
));
1172 goto bad_fork_free_pid
;
1176 p
->pid
= pid_nr(pid
);
1178 if (clone_flags
& CLONE_THREAD
)
1179 p
->tgid
= current
->tgid
;
1181 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1183 * Clear TID on mm_release()?
1185 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1187 p
->robust_list
= NULL
;
1188 #ifdef CONFIG_COMPAT
1189 p
->compat_robust_list
= NULL
;
1191 INIT_LIST_HEAD(&p
->pi_state_list
);
1192 p
->pi_state_cache
= NULL
;
1195 * sigaltstack should be cleared when sharing the same VM
1197 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1198 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1201 * Syscall tracing should be turned off in the child regardless
1204 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1205 #ifdef TIF_SYSCALL_EMU
1206 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1208 clear_all_latency_tracing(p
);
1210 /* Our parent execution domain becomes current domain
1211 These must match for thread signalling to apply */
1212 p
->parent_exec_id
= p
->self_exec_id
;
1214 /* ok, now we should be set up.. */
1215 p
->exit_signal
= (clone_flags
& CLONE_THREAD
) ? -1 : (clone_flags
& CSIGNAL
);
1216 p
->pdeath_signal
= 0;
1220 * Ok, make it visible to the rest of the system.
1221 * We dont wake it up yet.
1223 p
->group_leader
= p
;
1224 INIT_LIST_HEAD(&p
->thread_group
);
1225 INIT_LIST_HEAD(&p
->ptrace_children
);
1226 INIT_LIST_HEAD(&p
->ptrace_list
);
1228 /* Now that the task is set up, run cgroup callbacks if
1229 * necessary. We need to run them before the task is visible
1230 * on the tasklist. */
1231 cgroup_fork_callbacks(p
);
1232 cgroup_callbacks_done
= 1;
1234 /* Need tasklist lock for parent etc handling! */
1235 write_lock_irq(&tasklist_lock
);
1237 /* for sys_ioprio_set(IOPRIO_WHO_PGRP) */
1238 p
->ioprio
= current
->ioprio
;
1241 * The task hasn't been attached yet, so its cpus_allowed mask will
1242 * not be changed, nor will its assigned CPU.
1244 * The cpus_allowed mask of the parent may have changed after it was
1245 * copied first time - so re-copy it here, then check the child's CPU
1246 * to ensure it is on a valid CPU (and if not, just force it back to
1247 * parent's CPU). This avoids alot of nasty races.
1249 p
->cpus_allowed
= current
->cpus_allowed
;
1250 p
->rt
.nr_cpus_allowed
= current
->rt
.nr_cpus_allowed
;
1251 if (unlikely(!cpu_isset(task_cpu(p
), p
->cpus_allowed
) ||
1252 !cpu_online(task_cpu(p
))))
1253 set_task_cpu(p
, smp_processor_id());
1255 /* CLONE_PARENT re-uses the old parent */
1256 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
))
1257 p
->real_parent
= current
->real_parent
;
1259 p
->real_parent
= current
;
1260 p
->parent
= p
->real_parent
;
1262 spin_lock(¤t
->sighand
->siglock
);
1265 * Process group and session signals need to be delivered to just the
1266 * parent before the fork or both the parent and the child after the
1267 * fork. Restart if a signal comes in before we add the new process to
1268 * it's process group.
1269 * A fatal signal pending means that current will exit, so the new
1270 * thread can't slip out of an OOM kill (or normal SIGKILL).
1272 recalc_sigpending();
1273 if (signal_pending(current
)) {
1274 spin_unlock(¤t
->sighand
->siglock
);
1275 write_unlock_irq(&tasklist_lock
);
1276 retval
= -ERESTARTNOINTR
;
1277 goto bad_fork_free_pid
;
1280 if (clone_flags
& CLONE_THREAD
) {
1281 p
->group_leader
= current
->group_leader
;
1282 list_add_tail_rcu(&p
->thread_group
, &p
->group_leader
->thread_group
);
1284 if (!cputime_eq(current
->signal
->it_virt_expires
,
1286 !cputime_eq(current
->signal
->it_prof_expires
,
1288 current
->signal
->rlim
[RLIMIT_CPU
].rlim_cur
!= RLIM_INFINITY
||
1289 !list_empty(¤t
->signal
->cpu_timers
[0]) ||
1290 !list_empty(¤t
->signal
->cpu_timers
[1]) ||
1291 !list_empty(¤t
->signal
->cpu_timers
[2])) {
1293 * Have child wake up on its first tick to check
1294 * for process CPU timers.
1296 p
->it_prof_expires
= jiffies_to_cputime(1);
1300 if (likely(p
->pid
)) {
1302 if (unlikely(p
->ptrace
& PT_PTRACED
))
1303 __ptrace_link(p
, current
->parent
);
1305 if (thread_group_leader(p
)) {
1306 if (clone_flags
& CLONE_NEWPID
)
1307 p
->nsproxy
->pid_ns
->child_reaper
= p
;
1309 p
->signal
->tty
= current
->signal
->tty
;
1310 set_task_pgrp(p
, task_pgrp_nr(current
));
1311 set_task_session(p
, task_session_nr(current
));
1312 attach_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1313 attach_pid(p
, PIDTYPE_SID
, task_session(current
));
1314 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1315 __get_cpu_var(process_counts
)++;
1317 attach_pid(p
, PIDTYPE_PID
, pid
);
1322 spin_unlock(¤t
->sighand
->siglock
);
1323 write_unlock_irq(&tasklist_lock
);
1324 proc_fork_connector(p
);
1325 cgroup_post_fork(p
);
1329 if (pid
!= &init_struct_pid
)
1331 bad_fork_cleanup_namespaces
:
1332 exit_task_namespaces(p
);
1333 bad_fork_cleanup_keys
:
1335 bad_fork_cleanup_mm
:
1338 bad_fork_cleanup_signal
:
1340 bad_fork_cleanup_sighand
:
1341 __cleanup_sighand(p
->sighand
);
1342 bad_fork_cleanup_fs
:
1343 exit_fs(p
); /* blocking */
1344 bad_fork_cleanup_files
:
1345 exit_files(p
); /* blocking */
1346 bad_fork_cleanup_semundo
:
1348 bad_fork_cleanup_audit
:
1350 bad_fork_cleanup_security
:
1351 security_task_free(p
);
1352 bad_fork_cleanup_policy
:
1354 mpol_free(p
->mempolicy
);
1355 bad_fork_cleanup_cgroup
:
1357 cgroup_exit(p
, cgroup_callbacks_done
);
1358 delayacct_tsk_free(p
);
1360 module_put(p
->binfmt
->module
);
1361 bad_fork_cleanup_put_domain
:
1362 module_put(task_thread_info(p
)->exec_domain
->module
);
1363 bad_fork_cleanup_count
:
1364 put_group_info(p
->group_info
);
1365 atomic_dec(&p
->user
->processes
);
1370 return ERR_PTR(retval
);
1373 noinline
struct pt_regs
* __devinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1375 memset(regs
, 0, sizeof(struct pt_regs
));
1379 struct task_struct
* __cpuinit
fork_idle(int cpu
)
1381 struct task_struct
*task
;
1382 struct pt_regs regs
;
1384 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
,
1387 init_idle(task
, cpu
);
1392 static int fork_traceflag(unsigned clone_flags
)
1394 if (clone_flags
& CLONE_UNTRACED
)
1396 else if (clone_flags
& CLONE_VFORK
) {
1397 if (current
->ptrace
& PT_TRACE_VFORK
)
1398 return PTRACE_EVENT_VFORK
;
1399 } else if ((clone_flags
& CSIGNAL
) != SIGCHLD
) {
1400 if (current
->ptrace
& PT_TRACE_CLONE
)
1401 return PTRACE_EVENT_CLONE
;
1402 } else if (current
->ptrace
& PT_TRACE_FORK
)
1403 return PTRACE_EVENT_FORK
;
1409 * Ok, this is the main fork-routine.
1411 * It copies the process, and if successful kick-starts
1412 * it and waits for it to finish using the VM if required.
1414 long do_fork(unsigned long clone_flags
,
1415 unsigned long stack_start
,
1416 struct pt_regs
*regs
,
1417 unsigned long stack_size
,
1418 int __user
*parent_tidptr
,
1419 int __user
*child_tidptr
)
1421 struct task_struct
*p
;
1425 if (unlikely(current
->ptrace
)) {
1426 trace
= fork_traceflag (clone_flags
);
1428 clone_flags
|= CLONE_PTRACE
;
1431 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
,
1432 child_tidptr
, NULL
);
1434 * Do this prior waking up the new thread - the thread pointer
1435 * might get invalid after that point, if the thread exits quickly.
1438 struct completion vfork
;
1441 * this is enough to call pid_nr_ns here, but this if
1442 * improves optimisation of regular fork()
1444 nr
= (clone_flags
& CLONE_NEWPID
) ?
1445 task_pid_nr_ns(p
, current
->nsproxy
->pid_ns
) :
1448 if (clone_flags
& CLONE_PARENT_SETTID
)
1449 put_user(nr
, parent_tidptr
);
1451 if (clone_flags
& CLONE_VFORK
) {
1452 p
->vfork_done
= &vfork
;
1453 init_completion(&vfork
);
1456 if ((p
->ptrace
& PT_PTRACED
) || (clone_flags
& CLONE_STOPPED
)) {
1458 * We'll start up with an immediate SIGSTOP.
1460 sigaddset(&p
->pending
.signal
, SIGSTOP
);
1461 set_tsk_thread_flag(p
, TIF_SIGPENDING
);
1464 if (!(clone_flags
& CLONE_STOPPED
))
1465 wake_up_new_task(p
, clone_flags
);
1467 p
->state
= TASK_STOPPED
;
1469 if (unlikely (trace
)) {
1470 current
->ptrace_message
= nr
;
1471 ptrace_notify ((trace
<< 8) | SIGTRAP
);
1474 if (clone_flags
& CLONE_VFORK
) {
1475 freezer_do_not_count();
1476 wait_for_completion(&vfork
);
1478 if (unlikely (current
->ptrace
& PT_TRACE_VFORK_DONE
)) {
1479 current
->ptrace_message
= nr
;
1480 ptrace_notify ((PTRACE_EVENT_VFORK_DONE
<< 8) | SIGTRAP
);
1489 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1490 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1493 static void sighand_ctor(struct kmem_cache
*cachep
, void *data
)
1495 struct sighand_struct
*sighand
= data
;
1497 spin_lock_init(&sighand
->siglock
);
1498 init_waitqueue_head(&sighand
->signalfd_wqh
);
1501 void __init
proc_caches_init(void)
1503 sighand_cachep
= kmem_cache_create("sighand_cache",
1504 sizeof(struct sighand_struct
), 0,
1505 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
,
1507 signal_cachep
= kmem_cache_create("signal_cache",
1508 sizeof(struct signal_struct
), 0,
1509 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1510 files_cachep
= kmem_cache_create("files_cache",
1511 sizeof(struct files_struct
), 0,
1512 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1513 fs_cachep
= kmem_cache_create("fs_cache",
1514 sizeof(struct fs_struct
), 0,
1515 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1516 vm_area_cachep
= kmem_cache_create("vm_area_struct",
1517 sizeof(struct vm_area_struct
), 0,
1519 mm_cachep
= kmem_cache_create("mm_struct",
1520 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1521 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1525 * Check constraints on flags passed to the unshare system call and
1526 * force unsharing of additional process context as appropriate.
1528 static void check_unshare_flags(unsigned long *flags_ptr
)
1531 * If unsharing a thread from a thread group, must also
1534 if (*flags_ptr
& CLONE_THREAD
)
1535 *flags_ptr
|= CLONE_VM
;
1538 * If unsharing vm, must also unshare signal handlers.
1540 if (*flags_ptr
& CLONE_VM
)
1541 *flags_ptr
|= CLONE_SIGHAND
;
1544 * If unsharing signal handlers and the task was created
1545 * using CLONE_THREAD, then must unshare the thread
1547 if ((*flags_ptr
& CLONE_SIGHAND
) &&
1548 (atomic_read(¤t
->signal
->count
) > 1))
1549 *flags_ptr
|= CLONE_THREAD
;
1552 * If unsharing namespace, must also unshare filesystem information.
1554 if (*flags_ptr
& CLONE_NEWNS
)
1555 *flags_ptr
|= CLONE_FS
;
1559 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1561 static int unshare_thread(unsigned long unshare_flags
)
1563 if (unshare_flags
& CLONE_THREAD
)
1570 * Unshare the filesystem structure if it is being shared
1572 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1574 struct fs_struct
*fs
= current
->fs
;
1576 if ((unshare_flags
& CLONE_FS
) &&
1577 (fs
&& atomic_read(&fs
->count
) > 1)) {
1578 *new_fsp
= __copy_fs_struct(current
->fs
);
1587 * Unsharing of sighand is not supported yet
1589 static int unshare_sighand(unsigned long unshare_flags
, struct sighand_struct
**new_sighp
)
1591 struct sighand_struct
*sigh
= current
->sighand
;
1593 if ((unshare_flags
& CLONE_SIGHAND
) && atomic_read(&sigh
->count
) > 1)
1600 * Unshare vm if it is being shared
1602 static int unshare_vm(unsigned long unshare_flags
, struct mm_struct
**new_mmp
)
1604 struct mm_struct
*mm
= current
->mm
;
1606 if ((unshare_flags
& CLONE_VM
) &&
1607 (mm
&& atomic_read(&mm
->mm_users
) > 1)) {
1615 * Unshare file descriptor table if it is being shared
1617 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1619 struct files_struct
*fd
= current
->files
;
1622 if ((unshare_flags
& CLONE_FILES
) &&
1623 (fd
&& atomic_read(&fd
->count
) > 1)) {
1624 *new_fdp
= dup_fd(fd
, &error
);
1633 * Unsharing of semundo for tasks created with CLONE_SYSVSEM is not
1636 static int unshare_semundo(unsigned long unshare_flags
, struct sem_undo_list
**new_ulistp
)
1638 if (unshare_flags
& CLONE_SYSVSEM
)
1645 * unshare allows a process to 'unshare' part of the process
1646 * context which was originally shared using clone. copy_*
1647 * functions used by do_fork() cannot be used here directly
1648 * because they modify an inactive task_struct that is being
1649 * constructed. Here we are modifying the current, active,
1652 asmlinkage
long sys_unshare(unsigned long unshare_flags
)
1655 struct fs_struct
*fs
, *new_fs
= NULL
;
1656 struct sighand_struct
*new_sigh
= NULL
;
1657 struct mm_struct
*mm
, *new_mm
= NULL
, *active_mm
= NULL
;
1658 struct files_struct
*fd
, *new_fd
= NULL
;
1659 struct sem_undo_list
*new_ulist
= NULL
;
1660 struct nsproxy
*new_nsproxy
= NULL
;
1662 check_unshare_flags(&unshare_flags
);
1664 /* Return -EINVAL for all unsupported flags */
1666 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1667 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1668 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWUSER
|
1670 goto bad_unshare_out
;
1672 if ((err
= unshare_thread(unshare_flags
)))
1673 goto bad_unshare_out
;
1674 if ((err
= unshare_fs(unshare_flags
, &new_fs
)))
1675 goto bad_unshare_cleanup_thread
;
1676 if ((err
= unshare_sighand(unshare_flags
, &new_sigh
)))
1677 goto bad_unshare_cleanup_fs
;
1678 if ((err
= unshare_vm(unshare_flags
, &new_mm
)))
1679 goto bad_unshare_cleanup_sigh
;
1680 if ((err
= unshare_fd(unshare_flags
, &new_fd
)))
1681 goto bad_unshare_cleanup_vm
;
1682 if ((err
= unshare_semundo(unshare_flags
, &new_ulist
)))
1683 goto bad_unshare_cleanup_fd
;
1684 if ((err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
1686 goto bad_unshare_cleanup_semundo
;
1688 if (new_fs
|| new_mm
|| new_fd
|| new_ulist
|| new_nsproxy
) {
1691 switch_task_namespaces(current
, new_nsproxy
);
1699 current
->fs
= new_fs
;
1705 active_mm
= current
->active_mm
;
1706 current
->mm
= new_mm
;
1707 current
->active_mm
= new_mm
;
1708 activate_mm(active_mm
, new_mm
);
1713 fd
= current
->files
;
1714 current
->files
= new_fd
;
1718 task_unlock(current
);
1722 put_nsproxy(new_nsproxy
);
1724 bad_unshare_cleanup_semundo
:
1725 bad_unshare_cleanup_fd
:
1727 put_files_struct(new_fd
);
1729 bad_unshare_cleanup_vm
:
1733 bad_unshare_cleanup_sigh
:
1735 if (atomic_dec_and_test(&new_sigh
->count
))
1736 kmem_cache_free(sighand_cachep
, new_sigh
);
1738 bad_unshare_cleanup_fs
:
1740 put_fs_struct(new_fs
);
1742 bad_unshare_cleanup_thread
: