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![Linus Torvalds](/assets/img/avatar_default.png)
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (28 commits) rcu: Move end of special early-boot RCU operation earlier rcu: Changes from reviews: avoid casts, fix/add warnings, improve comments rcu: Create rcutree plugins to handle hotplug CPU for multi-level trees rcu: Remove lockdep annotations from RCU's _notrace() API members rcu: Add #ifdef to suppress __rcu_offline_cpu() warning in !HOTPLUG_CPU builds rcu: Add CPU-offline processing for single-node configurations rcu: Add "notrace" to RCU function headers used by ftrace rcu: Remove CONFIG_PREEMPT_RCU rcu: Merge preemptable-RCU functionality into hierarchical RCU rcu: Simplify rcu_pending()/rcu_check_callbacks() API rcu: Use debugfs_remove_recursive() simplify code. rcu: Merge per-RCU-flavor initialization into pre-existing macro rcu: Fix online/offline indication for rcudata.csv trace file rcu: Consolidate sparse and lockdep declarations in include/linux/rcupdate.h rcu: Renamings to increase RCU clarity rcu: Move private definitions from include/linux/rcutree.h to kernel/rcutree.h rcu: Expunge lingering references to CONFIG_CLASSIC_RCU, optimize on !SMP rcu: Delay rcu_barrier() wait until beginning of next CPU-hotunplug operation. rcu: Fix typo in rcu_irq_exit() comment header rcu: Make rcupreempt_trace.c look at offline CPUs ...
1720 lines
41 KiB
C
1720 lines
41 KiB
C
/*
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* linux/kernel/fork.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* 'fork.c' contains the help-routines for the 'fork' system call
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* (see also entry.S and others).
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* Fork is rather simple, once you get the hang of it, but the memory
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* management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
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*/
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/unistd.h>
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#include <linux/module.h>
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#include <linux/vmalloc.h>
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#include <linux/completion.h>
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#include <linux/personality.h>
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#include <linux/mempolicy.h>
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#include <linux/sem.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/iocontext.h>
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#include <linux/key.h>
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#include <linux/binfmts.h>
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#include <linux/mman.h>
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#include <linux/mmu_notifier.h>
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#include <linux/fs.h>
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#include <linux/nsproxy.h>
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#include <linux/capability.h>
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#include <linux/cpu.h>
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#include <linux/cgroup.h>
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#include <linux/security.h>
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#include <linux/hugetlb.h>
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#include <linux/swap.h>
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#include <linux/syscalls.h>
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#include <linux/jiffies.h>
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#include <linux/tracehook.h>
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#include <linux/futex.h>
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#include <linux/compat.h>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/rcupdate.h>
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#include <linux/ptrace.h>
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#include <linux/mount.h>
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#include <linux/audit.h>
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#include <linux/memcontrol.h>
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#include <linux/ftrace.h>
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#include <linux/profile.h>
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#include <linux/rmap.h>
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#include <linux/acct.h>
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#include <linux/tsacct_kern.h>
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#include <linux/cn_proc.h>
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#include <linux/freezer.h>
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#include <linux/delayacct.h>
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#include <linux/taskstats_kern.h>
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#include <linux/random.h>
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#include <linux/tty.h>
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#include <linux/proc_fs.h>
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#include <linux/blkdev.h>
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#include <linux/fs_struct.h>
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#include <linux/magic.h>
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#include <linux/perf_counter.h>
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#include <asm/pgtable.h>
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#include <asm/pgalloc.h>
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#include <asm/uaccess.h>
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#include <asm/mmu_context.h>
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#include <asm/cacheflush.h>
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#include <asm/tlbflush.h>
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#include <trace/events/sched.h>
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/*
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* Protected counters by write_lock_irq(&tasklist_lock)
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*/
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unsigned long total_forks; /* Handle normal Linux uptimes. */
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int nr_threads; /* The idle threads do not count.. */
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int max_threads; /* tunable limit on nr_threads */
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DEFINE_PER_CPU(unsigned long, process_counts) = 0;
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__cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
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int nr_processes(void)
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{
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int cpu;
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int total = 0;
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for_each_online_cpu(cpu)
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total += per_cpu(process_counts, cpu);
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return total;
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}
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#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
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# define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
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# define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
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static struct kmem_cache *task_struct_cachep;
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#endif
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#ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
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static inline struct thread_info *alloc_thread_info(struct task_struct *tsk)
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{
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#ifdef CONFIG_DEBUG_STACK_USAGE
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gfp_t mask = GFP_KERNEL | __GFP_ZERO;
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#else
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gfp_t mask = GFP_KERNEL;
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#endif
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return (struct thread_info *)__get_free_pages(mask, THREAD_SIZE_ORDER);
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}
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static inline void free_thread_info(struct thread_info *ti)
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{
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free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
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}
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#endif
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/* SLAB cache for signal_struct structures (tsk->signal) */
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static struct kmem_cache *signal_cachep;
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/* SLAB cache for sighand_struct structures (tsk->sighand) */
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struct kmem_cache *sighand_cachep;
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/* SLAB cache for files_struct structures (tsk->files) */
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struct kmem_cache *files_cachep;
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/* SLAB cache for fs_struct structures (tsk->fs) */
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struct kmem_cache *fs_cachep;
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/* SLAB cache for vm_area_struct structures */
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struct kmem_cache *vm_area_cachep;
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/* SLAB cache for mm_struct structures (tsk->mm) */
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static struct kmem_cache *mm_cachep;
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void free_task(struct task_struct *tsk)
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{
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prop_local_destroy_single(&tsk->dirties);
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free_thread_info(tsk->stack);
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rt_mutex_debug_task_free(tsk);
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ftrace_graph_exit_task(tsk);
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free_task_struct(tsk);
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}
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EXPORT_SYMBOL(free_task);
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void __put_task_struct(struct task_struct *tsk)
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{
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WARN_ON(!tsk->exit_state);
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WARN_ON(atomic_read(&tsk->usage));
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WARN_ON(tsk == current);
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exit_creds(tsk);
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delayacct_tsk_free(tsk);
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if (!profile_handoff_task(tsk))
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free_task(tsk);
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}
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/*
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* macro override instead of weak attribute alias, to workaround
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* gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
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*/
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#ifndef arch_task_cache_init
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#define arch_task_cache_init()
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#endif
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void __init fork_init(unsigned long mempages)
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{
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#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
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#ifndef ARCH_MIN_TASKALIGN
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#define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
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#endif
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/* create a slab on which task_structs can be allocated */
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task_struct_cachep =
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kmem_cache_create("task_struct", sizeof(struct task_struct),
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ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL);
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#endif
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/* do the arch specific task caches init */
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arch_task_cache_init();
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/*
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* The default maximum number of threads is set to a safe
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* value: the thread structures can take up at most half
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* of memory.
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*/
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max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
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/*
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* we need to allow at least 20 threads to boot a system
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*/
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if(max_threads < 20)
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max_threads = 20;
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init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
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init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
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init_task.signal->rlim[RLIMIT_SIGPENDING] =
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init_task.signal->rlim[RLIMIT_NPROC];
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}
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int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
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struct task_struct *src)
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{
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*dst = *src;
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return 0;
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}
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static struct task_struct *dup_task_struct(struct task_struct *orig)
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{
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struct task_struct *tsk;
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struct thread_info *ti;
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unsigned long *stackend;
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int err;
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prepare_to_copy(orig);
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tsk = alloc_task_struct();
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if (!tsk)
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return NULL;
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ti = alloc_thread_info(tsk);
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if (!ti) {
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free_task_struct(tsk);
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return NULL;
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}
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err = arch_dup_task_struct(tsk, orig);
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if (err)
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goto out;
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tsk->stack = ti;
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err = prop_local_init_single(&tsk->dirties);
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if (err)
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goto out;
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setup_thread_stack(tsk, orig);
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stackend = end_of_stack(tsk);
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*stackend = STACK_END_MAGIC; /* for overflow detection */
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#ifdef CONFIG_CC_STACKPROTECTOR
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tsk->stack_canary = get_random_int();
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#endif
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/* One for us, one for whoever does the "release_task()" (usually parent) */
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atomic_set(&tsk->usage,2);
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atomic_set(&tsk->fs_excl, 0);
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#ifdef CONFIG_BLK_DEV_IO_TRACE
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tsk->btrace_seq = 0;
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#endif
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tsk->splice_pipe = NULL;
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return tsk;
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out:
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free_thread_info(ti);
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free_task_struct(tsk);
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return NULL;
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}
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#ifdef CONFIG_MMU
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static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
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{
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struct vm_area_struct *mpnt, *tmp, **pprev;
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struct rb_node **rb_link, *rb_parent;
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int retval;
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unsigned long charge;
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struct mempolicy *pol;
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down_write(&oldmm->mmap_sem);
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flush_cache_dup_mm(oldmm);
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/*
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* Not linked in yet - no deadlock potential:
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*/
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down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
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mm->locked_vm = 0;
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mm->mmap = NULL;
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mm->mmap_cache = NULL;
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mm->free_area_cache = oldmm->mmap_base;
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mm->cached_hole_size = ~0UL;
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mm->map_count = 0;
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cpumask_clear(mm_cpumask(mm));
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mm->mm_rb = RB_ROOT;
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rb_link = &mm->mm_rb.rb_node;
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rb_parent = NULL;
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pprev = &mm->mmap;
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for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
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struct file *file;
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if (mpnt->vm_flags & VM_DONTCOPY) {
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long pages = vma_pages(mpnt);
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mm->total_vm -= pages;
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vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
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-pages);
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continue;
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}
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charge = 0;
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if (mpnt->vm_flags & VM_ACCOUNT) {
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unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
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if (security_vm_enough_memory(len))
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goto fail_nomem;
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charge = len;
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}
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tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
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if (!tmp)
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goto fail_nomem;
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*tmp = *mpnt;
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pol = mpol_dup(vma_policy(mpnt));
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retval = PTR_ERR(pol);
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if (IS_ERR(pol))
|
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goto fail_nomem_policy;
|
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vma_set_policy(tmp, pol);
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tmp->vm_flags &= ~VM_LOCKED;
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tmp->vm_mm = mm;
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tmp->vm_next = NULL;
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anon_vma_link(tmp);
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file = tmp->vm_file;
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if (file) {
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struct inode *inode = file->f_path.dentry->d_inode;
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struct address_space *mapping = file->f_mapping;
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get_file(file);
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if (tmp->vm_flags & VM_DENYWRITE)
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atomic_dec(&inode->i_writecount);
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spin_lock(&mapping->i_mmap_lock);
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if (tmp->vm_flags & VM_SHARED)
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mapping->i_mmap_writable++;
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tmp->vm_truncate_count = mpnt->vm_truncate_count;
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flush_dcache_mmap_lock(mapping);
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/* insert tmp into the share list, just after mpnt */
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vma_prio_tree_add(tmp, mpnt);
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flush_dcache_mmap_unlock(mapping);
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spin_unlock(&mapping->i_mmap_lock);
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}
|
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|
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/*
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* Clear hugetlb-related page reserves for children. This only
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* affects MAP_PRIVATE mappings. Faults generated by the child
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* are not guaranteed to succeed, even if read-only
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*/
|
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if (is_vm_hugetlb_page(tmp))
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reset_vma_resv_huge_pages(tmp);
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|
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/*
|
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* Link in the new vma and copy the page table entries.
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*/
|
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*pprev = tmp;
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pprev = &tmp->vm_next;
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|
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__vma_link_rb(mm, tmp, rb_link, rb_parent);
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rb_link = &tmp->vm_rb.rb_right;
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rb_parent = &tmp->vm_rb;
|
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|
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mm->map_count++;
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retval = copy_page_range(mm, oldmm, mpnt);
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|
|
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if (tmp->vm_ops && tmp->vm_ops->open)
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tmp->vm_ops->open(tmp);
|
|
|
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if (retval)
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goto out;
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}
|
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/* a new mm has just been created */
|
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arch_dup_mmap(oldmm, mm);
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retval = 0;
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out:
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up_write(&mm->mmap_sem);
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flush_tlb_mm(oldmm);
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up_write(&oldmm->mmap_sem);
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return retval;
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fail_nomem_policy:
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kmem_cache_free(vm_area_cachep, tmp);
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fail_nomem:
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retval = -ENOMEM;
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vm_unacct_memory(charge);
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goto out;
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}
|
|
|
|
static inline int mm_alloc_pgd(struct mm_struct * mm)
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{
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mm->pgd = pgd_alloc(mm);
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if (unlikely(!mm->pgd))
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return -ENOMEM;
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return 0;
|
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}
|
|
|
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static inline void mm_free_pgd(struct mm_struct * mm)
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{
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pgd_free(mm, mm->pgd);
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}
|
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#else
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#define dup_mmap(mm, oldmm) (0)
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#define mm_alloc_pgd(mm) (0)
|
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#define mm_free_pgd(mm)
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#endif /* CONFIG_MMU */
|
|
|
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__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
|
|
|
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#define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
|
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#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
|
|
|
|
static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
|
|
|
|
static int __init coredump_filter_setup(char *s)
|
|
{
|
|
default_dump_filter =
|
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(simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
|
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MMF_DUMP_FILTER_MASK;
|
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return 1;
|
|
}
|
|
|
|
__setup("coredump_filter=", coredump_filter_setup);
|
|
|
|
#include <linux/init_task.h>
|
|
|
|
static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p)
|
|
{
|
|
atomic_set(&mm->mm_users, 1);
|
|
atomic_set(&mm->mm_count, 1);
|
|
init_rwsem(&mm->mmap_sem);
|
|
INIT_LIST_HEAD(&mm->mmlist);
|
|
mm->flags = (current->mm) ? current->mm->flags : default_dump_filter;
|
|
mm->core_state = NULL;
|
|
mm->nr_ptes = 0;
|
|
set_mm_counter(mm, file_rss, 0);
|
|
set_mm_counter(mm, anon_rss, 0);
|
|
spin_lock_init(&mm->page_table_lock);
|
|
spin_lock_init(&mm->ioctx_lock);
|
|
INIT_HLIST_HEAD(&mm->ioctx_list);
|
|
mm->free_area_cache = TASK_UNMAPPED_BASE;
|
|
mm->cached_hole_size = ~0UL;
|
|
mm_init_owner(mm, p);
|
|
|
|
if (likely(!mm_alloc_pgd(mm))) {
|
|
mm->def_flags = 0;
|
|
mmu_notifier_mm_init(mm);
|
|
return mm;
|
|
}
|
|
|
|
free_mm(mm);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Allocate and initialize an mm_struct.
|
|
*/
|
|
struct mm_struct * mm_alloc(void)
|
|
{
|
|
struct mm_struct * mm;
|
|
|
|
mm = allocate_mm();
|
|
if (mm) {
|
|
memset(mm, 0, sizeof(*mm));
|
|
mm = mm_init(mm, current);
|
|
}
|
|
return mm;
|
|
}
|
|
|
|
/*
|
|
* Called when the last reference to the mm
|
|
* is dropped: either by a lazy thread or by
|
|
* mmput. Free the page directory and the mm.
|
|
*/
|
|
void __mmdrop(struct mm_struct *mm)
|
|
{
|
|
BUG_ON(mm == &init_mm);
|
|
mm_free_pgd(mm);
|
|
destroy_context(mm);
|
|
mmu_notifier_mm_destroy(mm);
|
|
free_mm(mm);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__mmdrop);
|
|
|
|
/*
|
|
* Decrement the use count and release all resources for an mm.
|
|
*/
|
|
void mmput(struct mm_struct *mm)
|
|
{
|
|
might_sleep();
|
|
|
|
if (atomic_dec_and_test(&mm->mm_users)) {
|
|
exit_aio(mm);
|
|
exit_mmap(mm);
|
|
set_mm_exe_file(mm, NULL);
|
|
if (!list_empty(&mm->mmlist)) {
|
|
spin_lock(&mmlist_lock);
|
|
list_del(&mm->mmlist);
|
|
spin_unlock(&mmlist_lock);
|
|
}
|
|
put_swap_token(mm);
|
|
mmdrop(mm);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(mmput);
|
|
|
|
/**
|
|
* get_task_mm - acquire a reference to the task's mm
|
|
*
|
|
* Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
|
|
* this kernel workthread has transiently adopted a user mm with use_mm,
|
|
* to do its AIO) is not set and if so returns a reference to it, after
|
|
* bumping up the use count. User must release the mm via mmput()
|
|
* after use. Typically used by /proc and ptrace.
|
|
*/
|
|
struct mm_struct *get_task_mm(struct task_struct *task)
|
|
{
|
|
struct mm_struct *mm;
|
|
|
|
task_lock(task);
|
|
mm = task->mm;
|
|
if (mm) {
|
|
if (task->flags & PF_KTHREAD)
|
|
mm = NULL;
|
|
else
|
|
atomic_inc(&mm->mm_users);
|
|
}
|
|
task_unlock(task);
|
|
return mm;
|
|
}
|
|
EXPORT_SYMBOL_GPL(get_task_mm);
|
|
|
|
/* Please note the differences between mmput and mm_release.
|
|
* mmput is called whenever we stop holding onto a mm_struct,
|
|
* error success whatever.
|
|
*
|
|
* mm_release is called after a mm_struct has been removed
|
|
* from the current process.
|
|
*
|
|
* This difference is important for error handling, when we
|
|
* only half set up a mm_struct for a new process and need to restore
|
|
* the old one. Because we mmput the new mm_struct before
|
|
* restoring the old one. . .
|
|
* Eric Biederman 10 January 1998
|
|
*/
|
|
void mm_release(struct task_struct *tsk, struct mm_struct *mm)
|
|
{
|
|
struct completion *vfork_done = tsk->vfork_done;
|
|
|
|
/* Get rid of any futexes when releasing the mm */
|
|
#ifdef CONFIG_FUTEX
|
|
if (unlikely(tsk->robust_list))
|
|
exit_robust_list(tsk);
|
|
#ifdef CONFIG_COMPAT
|
|
if (unlikely(tsk->compat_robust_list))
|
|
compat_exit_robust_list(tsk);
|
|
#endif
|
|
#endif
|
|
|
|
/* Get rid of any cached register state */
|
|
deactivate_mm(tsk, mm);
|
|
|
|
/* notify parent sleeping on vfork() */
|
|
if (vfork_done) {
|
|
tsk->vfork_done = NULL;
|
|
complete(vfork_done);
|
|
}
|
|
|
|
/*
|
|
* If we're exiting normally, clear a user-space tid field if
|
|
* requested. We leave this alone when dying by signal, to leave
|
|
* the value intact in a core dump, and to save the unnecessary
|
|
* trouble otherwise. Userland only wants this done for a sys_exit.
|
|
*/
|
|
if (tsk->clear_child_tid) {
|
|
if (!(tsk->flags & PF_SIGNALED) &&
|
|
atomic_read(&mm->mm_users) > 1) {
|
|
/*
|
|
* We don't check the error code - if userspace has
|
|
* not set up a proper pointer then tough luck.
|
|
*/
|
|
put_user(0, tsk->clear_child_tid);
|
|
sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
|
|
1, NULL, NULL, 0);
|
|
}
|
|
tsk->clear_child_tid = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocate a new mm structure and copy contents from the
|
|
* mm structure of the passed in task structure.
|
|
*/
|
|
struct mm_struct *dup_mm(struct task_struct *tsk)
|
|
{
|
|
struct mm_struct *mm, *oldmm = current->mm;
|
|
int err;
|
|
|
|
if (!oldmm)
|
|
return NULL;
|
|
|
|
mm = allocate_mm();
|
|
if (!mm)
|
|
goto fail_nomem;
|
|
|
|
memcpy(mm, oldmm, sizeof(*mm));
|
|
|
|
/* Initializing for Swap token stuff */
|
|
mm->token_priority = 0;
|
|
mm->last_interval = 0;
|
|
|
|
if (!mm_init(mm, tsk))
|
|
goto fail_nomem;
|
|
|
|
if (init_new_context(tsk, mm))
|
|
goto fail_nocontext;
|
|
|
|
dup_mm_exe_file(oldmm, mm);
|
|
|
|
err = dup_mmap(mm, oldmm);
|
|
if (err)
|
|
goto free_pt;
|
|
|
|
mm->hiwater_rss = get_mm_rss(mm);
|
|
mm->hiwater_vm = mm->total_vm;
|
|
|
|
return mm;
|
|
|
|
free_pt:
|
|
mmput(mm);
|
|
|
|
fail_nomem:
|
|
return NULL;
|
|
|
|
fail_nocontext:
|
|
/*
|
|
* If init_new_context() failed, we cannot use mmput() to free the mm
|
|
* because it calls destroy_context()
|
|
*/
|
|
mm_free_pgd(mm);
|
|
free_mm(mm);
|
|
return NULL;
|
|
}
|
|
|
|
static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
|
|
{
|
|
struct mm_struct * mm, *oldmm;
|
|
int retval;
|
|
|
|
tsk->min_flt = tsk->maj_flt = 0;
|
|
tsk->nvcsw = tsk->nivcsw = 0;
|
|
#ifdef CONFIG_DETECT_HUNG_TASK
|
|
tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
|
|
#endif
|
|
|
|
tsk->mm = NULL;
|
|
tsk->active_mm = NULL;
|
|
|
|
/*
|
|
* Are we cloning a kernel thread?
|
|
*
|
|
* We need to steal a active VM for that..
|
|
*/
|
|
oldmm = current->mm;
|
|
if (!oldmm)
|
|
return 0;
|
|
|
|
if (clone_flags & CLONE_VM) {
|
|
atomic_inc(&oldmm->mm_users);
|
|
mm = oldmm;
|
|
goto good_mm;
|
|
}
|
|
|
|
retval = -ENOMEM;
|
|
mm = dup_mm(tsk);
|
|
if (!mm)
|
|
goto fail_nomem;
|
|
|
|
good_mm:
|
|
/* Initializing for Swap token stuff */
|
|
mm->token_priority = 0;
|
|
mm->last_interval = 0;
|
|
|
|
tsk->mm = mm;
|
|
tsk->active_mm = mm;
|
|
return 0;
|
|
|
|
fail_nomem:
|
|
return retval;
|
|
}
|
|
|
|
static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct fs_struct *fs = current->fs;
|
|
if (clone_flags & CLONE_FS) {
|
|
/* tsk->fs is already what we want */
|
|
write_lock(&fs->lock);
|
|
if (fs->in_exec) {
|
|
write_unlock(&fs->lock);
|
|
return -EAGAIN;
|
|
}
|
|
fs->users++;
|
|
write_unlock(&fs->lock);
|
|
return 0;
|
|
}
|
|
tsk->fs = copy_fs_struct(fs);
|
|
if (!tsk->fs)
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
|
|
static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
|
|
{
|
|
struct files_struct *oldf, *newf;
|
|
int error = 0;
|
|
|
|
/*
|
|
* A background process may not have any files ...
|
|
*/
|
|
oldf = current->files;
|
|
if (!oldf)
|
|
goto out;
|
|
|
|
if (clone_flags & CLONE_FILES) {
|
|
atomic_inc(&oldf->count);
|
|
goto out;
|
|
}
|
|
|
|
newf = dup_fd(oldf, &error);
|
|
if (!newf)
|
|
goto out;
|
|
|
|
tsk->files = newf;
|
|
error = 0;
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
#ifdef CONFIG_BLOCK
|
|
struct io_context *ioc = current->io_context;
|
|
|
|
if (!ioc)
|
|
return 0;
|
|
/*
|
|
* Share io context with parent, if CLONE_IO is set
|
|
*/
|
|
if (clone_flags & CLONE_IO) {
|
|
tsk->io_context = ioc_task_link(ioc);
|
|
if (unlikely(!tsk->io_context))
|
|
return -ENOMEM;
|
|
} else if (ioprio_valid(ioc->ioprio)) {
|
|
tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
|
|
if (unlikely(!tsk->io_context))
|
|
return -ENOMEM;
|
|
|
|
tsk->io_context->ioprio = ioc->ioprio;
|
|
}
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct sighand_struct *sig;
|
|
|
|
if (clone_flags & CLONE_SIGHAND) {
|
|
atomic_inc(¤t->sighand->count);
|
|
return 0;
|
|
}
|
|
sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
|
|
rcu_assign_pointer(tsk->sighand, sig);
|
|
if (!sig)
|
|
return -ENOMEM;
|
|
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);
|
|
}
|
|
|
|
|
|
/*
|
|
* Initialize POSIX timer handling for a thread group.
|
|
*/
|
|
static void posix_cpu_timers_init_group(struct signal_struct *sig)
|
|
{
|
|
/* Thread group counters. */
|
|
thread_group_cputime_init(sig);
|
|
|
|
/* Expiration times and increments. */
|
|
sig->it_virt_expires = cputime_zero;
|
|
sig->it_virt_incr = cputime_zero;
|
|
sig->it_prof_expires = cputime_zero;
|
|
sig->it_prof_incr = cputime_zero;
|
|
|
|
/* Cached expiration times. */
|
|
sig->cputime_expires.prof_exp = cputime_zero;
|
|
sig->cputime_expires.virt_exp = cputime_zero;
|
|
sig->cputime_expires.sched_exp = 0;
|
|
|
|
if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
|
|
sig->cputime_expires.prof_exp =
|
|
secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
|
|
sig->cputimer.running = 1;
|
|
}
|
|
|
|
/* The timer lists. */
|
|
INIT_LIST_HEAD(&sig->cpu_timers[0]);
|
|
INIT_LIST_HEAD(&sig->cpu_timers[1]);
|
|
INIT_LIST_HEAD(&sig->cpu_timers[2]);
|
|
}
|
|
|
|
static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct signal_struct *sig;
|
|
|
|
if (clone_flags & CLONE_THREAD)
|
|
return 0;
|
|
|
|
sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
|
|
tsk->signal = sig;
|
|
if (!sig)
|
|
return -ENOMEM;
|
|
|
|
atomic_set(&sig->count, 1);
|
|
atomic_set(&sig->live, 1);
|
|
init_waitqueue_head(&sig->wait_chldexit);
|
|
sig->flags = 0;
|
|
if (clone_flags & CLONE_NEWPID)
|
|
sig->flags |= SIGNAL_UNKILLABLE;
|
|
sig->group_exit_code = 0;
|
|
sig->group_exit_task = NULL;
|
|
sig->group_stop_count = 0;
|
|
sig->curr_target = tsk;
|
|
init_sigpending(&sig->shared_pending);
|
|
INIT_LIST_HEAD(&sig->posix_timers);
|
|
|
|
hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
|
sig->it_real_incr.tv64 = 0;
|
|
sig->real_timer.function = it_real_fn;
|
|
|
|
sig->leader = 0; /* session leadership doesn't inherit */
|
|
sig->tty_old_pgrp = NULL;
|
|
sig->tty = NULL;
|
|
|
|
sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
|
|
sig->gtime = cputime_zero;
|
|
sig->cgtime = cputime_zero;
|
|
sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
|
|
sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
|
|
sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
|
|
task_io_accounting_init(&sig->ioac);
|
|
sig->sum_sched_runtime = 0;
|
|
taskstats_tgid_init(sig);
|
|
|
|
task_lock(current->group_leader);
|
|
memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
|
|
task_unlock(current->group_leader);
|
|
|
|
posix_cpu_timers_init_group(sig);
|
|
|
|
acct_init_pacct(&sig->pacct);
|
|
|
|
tty_audit_fork(sig);
|
|
|
|
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;
|
|
|
|
new_flags &= ~PF_SUPERPRIV;
|
|
new_flags |= PF_FORKNOEXEC;
|
|
new_flags |= PF_STARTING;
|
|
p->flags = new_flags;
|
|
clear_freeze_flag(p);
|
|
}
|
|
|
|
SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
|
|
{
|
|
current->clear_child_tid = tidptr;
|
|
|
|
return task_pid_vnr(current);
|
|
}
|
|
|
|
static void rt_mutex_init_task(struct task_struct *p)
|
|
{
|
|
spin_lock_init(&p->pi_lock);
|
|
#ifdef CONFIG_RT_MUTEXES
|
|
plist_head_init(&p->pi_waiters, &p->pi_lock);
|
|
p->pi_blocked_on = NULL;
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_MM_OWNER
|
|
void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
|
|
{
|
|
mm->owner = p;
|
|
}
|
|
#endif /* CONFIG_MM_OWNER */
|
|
|
|
/*
|
|
* Initialize POSIX timer handling for a single task.
|
|
*/
|
|
static void posix_cpu_timers_init(struct task_struct *tsk)
|
|
{
|
|
tsk->cputime_expires.prof_exp = cputime_zero;
|
|
tsk->cputime_expires.virt_exp = cputime_zero;
|
|
tsk->cputime_expires.sched_exp = 0;
|
|
INIT_LIST_HEAD(&tsk->cpu_timers[0]);
|
|
INIT_LIST_HEAD(&tsk->cpu_timers[1]);
|
|
INIT_LIST_HEAD(&tsk->cpu_timers[2]);
|
|
}
|
|
|
|
/*
|
|
* This creates a new process as a copy of the old one,
|
|
* but does not actually start it yet.
|
|
*
|
|
* It copies the registers, and all the appropriate
|
|
* parts of the process environment (as per the clone
|
|
* flags). The actual kick-off is left to the caller.
|
|
*/
|
|
static struct task_struct *copy_process(unsigned long clone_flags,
|
|
unsigned long stack_start,
|
|
struct pt_regs *regs,
|
|
unsigned long stack_size,
|
|
int __user *child_tidptr,
|
|
struct pid *pid,
|
|
int trace)
|
|
{
|
|
int retval;
|
|
struct task_struct *p;
|
|
int cgroup_callbacks_done = 0;
|
|
|
|
if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
/*
|
|
* Thread groups must share signals as well, and detached threads
|
|
* can only be started up within the thread group.
|
|
*/
|
|
if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
/*
|
|
* Shared signal handlers imply shared VM. By way of the above,
|
|
* thread groups also imply shared VM. Blocking this case allows
|
|
* for various simplifications in other code.
|
|
*/
|
|
if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
retval = security_task_create(clone_flags);
|
|
if (retval)
|
|
goto fork_out;
|
|
|
|
retval = -ENOMEM;
|
|
p = dup_task_struct(current);
|
|
if (!p)
|
|
goto fork_out;
|
|
|
|
ftrace_graph_init_task(p);
|
|
|
|
rt_mutex_init_task(p);
|
|
|
|
#ifdef CONFIG_PROVE_LOCKING
|
|
DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
|
|
DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
|
|
#endif
|
|
retval = -EAGAIN;
|
|
if (atomic_read(&p->real_cred->user->processes) >=
|
|
p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
|
|
if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
|
|
p->real_cred->user != INIT_USER)
|
|
goto bad_fork_free;
|
|
}
|
|
|
|
retval = copy_creds(p, clone_flags);
|
|
if (retval < 0)
|
|
goto bad_fork_free;
|
|
|
|
/*
|
|
* If multiple threads are within copy_process(), then this check
|
|
* triggers too late. This doesn't hurt, the check is only there
|
|
* to stop root fork bombs.
|
|
*/
|
|
retval = -EAGAIN;
|
|
if (nr_threads >= max_threads)
|
|
goto bad_fork_cleanup_count;
|
|
|
|
if (!try_module_get(task_thread_info(p)->exec_domain->module))
|
|
goto bad_fork_cleanup_count;
|
|
|
|
if (p->binfmt && !try_module_get(p->binfmt->module))
|
|
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);
|
|
INIT_LIST_HEAD(&p->children);
|
|
INIT_LIST_HEAD(&p->sibling);
|
|
rcu_copy_process(p);
|
|
p->vfork_done = NULL;
|
|
spin_lock_init(&p->alloc_lock);
|
|
|
|
init_sigpending(&p->pending);
|
|
|
|
p->utime = cputime_zero;
|
|
p->stime = cputime_zero;
|
|
p->gtime = cputime_zero;
|
|
p->utimescaled = cputime_zero;
|
|
p->stimescaled = cputime_zero;
|
|
p->prev_utime = cputime_zero;
|
|
p->prev_stime = cputime_zero;
|
|
|
|
p->default_timer_slack_ns = current->timer_slack_ns;
|
|
|
|
task_io_accounting_init(&p->ioac);
|
|
acct_clear_integrals(p);
|
|
|
|
posix_cpu_timers_init(p);
|
|
|
|
p->lock_depth = -1; /* -1 = no lock */
|
|
do_posix_clock_monotonic_gettime(&p->start_time);
|
|
p->real_start_time = p->start_time;
|
|
monotonic_to_bootbased(&p->real_start_time);
|
|
p->io_context = NULL;
|
|
p->audit_context = NULL;
|
|
cgroup_fork(p);
|
|
#ifdef CONFIG_NUMA
|
|
p->mempolicy = mpol_dup(p->mempolicy);
|
|
if (IS_ERR(p->mempolicy)) {
|
|
retval = PTR_ERR(p->mempolicy);
|
|
p->mempolicy = NULL;
|
|
goto bad_fork_cleanup_cgroup;
|
|
}
|
|
mpol_fix_fork_child_flag(p);
|
|
#endif
|
|
#ifdef CONFIG_TRACE_IRQFLAGS
|
|
p->irq_events = 0;
|
|
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
|
|
p->hardirqs_enabled = 1;
|
|
#else
|
|
p->hardirqs_enabled = 0;
|
|
#endif
|
|
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
|
|
|
|
#ifdef CONFIG_DEBUG_MUTEXES
|
|
p->blocked_on = NULL; /* not blocked yet */
|
|
#endif
|
|
|
|
p->bts = NULL;
|
|
|
|
/* Perform scheduler related setup. Assign this task to a CPU. */
|
|
sched_fork(p, clone_flags);
|
|
|
|
retval = perf_counter_init_task(p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_policy;
|
|
|
|
if ((retval = audit_alloc(p)))
|
|
goto bad_fork_cleanup_policy;
|
|
/* copy all the process information */
|
|
if ((retval = copy_semundo(clone_flags, p)))
|
|
goto bad_fork_cleanup_audit;
|
|
if ((retval = copy_files(clone_flags, p)))
|
|
goto bad_fork_cleanup_semundo;
|
|
if ((retval = copy_fs(clone_flags, p)))
|
|
goto bad_fork_cleanup_files;
|
|
if ((retval = copy_sighand(clone_flags, p)))
|
|
goto bad_fork_cleanup_fs;
|
|
if ((retval = copy_signal(clone_flags, p)))
|
|
goto bad_fork_cleanup_sighand;
|
|
if ((retval = copy_mm(clone_flags, p)))
|
|
goto bad_fork_cleanup_signal;
|
|
if ((retval = copy_namespaces(clone_flags, p)))
|
|
goto bad_fork_cleanup_mm;
|
|
if ((retval = copy_io(clone_flags, p)))
|
|
goto bad_fork_cleanup_namespaces;
|
|
retval = copy_thread(clone_flags, stack_start, stack_size, p, regs);
|
|
if (retval)
|
|
goto bad_fork_cleanup_io;
|
|
|
|
if (pid != &init_struct_pid) {
|
|
retval = -ENOMEM;
|
|
pid = alloc_pid(p->nsproxy->pid_ns);
|
|
if (!pid)
|
|
goto bad_fork_cleanup_io;
|
|
|
|
if (clone_flags & CLONE_NEWPID) {
|
|
retval = pid_ns_prepare_proc(p->nsproxy->pid_ns);
|
|
if (retval < 0)
|
|
goto bad_fork_free_pid;
|
|
}
|
|
}
|
|
|
|
p->pid = pid_nr(pid);
|
|
p->tgid = p->pid;
|
|
if (clone_flags & CLONE_THREAD)
|
|
p->tgid = current->tgid;
|
|
|
|
if (current->nsproxy != p->nsproxy) {
|
|
retval = ns_cgroup_clone(p, pid);
|
|
if (retval)
|
|
goto bad_fork_free_pid;
|
|
}
|
|
|
|
p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
|
|
/*
|
|
* Clear TID on mm_release()?
|
|
*/
|
|
p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
|
|
#ifdef CONFIG_FUTEX
|
|
p->robust_list = NULL;
|
|
#ifdef CONFIG_COMPAT
|
|
p->compat_robust_list = NULL;
|
|
#endif
|
|
INIT_LIST_HEAD(&p->pi_state_list);
|
|
p->pi_state_cache = NULL;
|
|
#endif
|
|
/*
|
|
* sigaltstack should be cleared when sharing the same VM
|
|
*/
|
|
if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
|
|
p->sas_ss_sp = p->sas_ss_size = 0;
|
|
|
|
/*
|
|
* Syscall tracing should be turned off in the child regardless
|
|
* of CLONE_PTRACE.
|
|
*/
|
|
clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
|
|
#ifdef TIF_SYSCALL_EMU
|
|
clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
|
|
#endif
|
|
clear_all_latency_tracing(p);
|
|
|
|
/* ok, now we should be set up.. */
|
|
p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
|
|
p->pdeath_signal = 0;
|
|
p->exit_state = 0;
|
|
|
|
/*
|
|
* Ok, make it visible to the rest of the system.
|
|
* We dont wake it up yet.
|
|
*/
|
|
p->group_leader = p;
|
|
INIT_LIST_HEAD(&p->thread_group);
|
|
|
|
/* Now that the task is set up, run cgroup callbacks if
|
|
* necessary. We need to run them before the task is visible
|
|
* on the tasklist. */
|
|
cgroup_fork_callbacks(p);
|
|
cgroup_callbacks_done = 1;
|
|
|
|
/* Need tasklist lock for parent etc handling! */
|
|
write_lock_irq(&tasklist_lock);
|
|
|
|
/*
|
|
* The task hasn't been attached yet, so its cpus_allowed mask will
|
|
* not be changed, nor will its assigned CPU.
|
|
*
|
|
* The cpus_allowed mask of the parent may have changed after it was
|
|
* copied first time - so re-copy it here, then check the child's CPU
|
|
* to ensure it is on a valid CPU (and if not, just force it back to
|
|
* parent's CPU). This avoids alot of nasty races.
|
|
*/
|
|
p->cpus_allowed = current->cpus_allowed;
|
|
p->rt.nr_cpus_allowed = current->rt.nr_cpus_allowed;
|
|
if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
|
|
!cpu_online(task_cpu(p))))
|
|
set_task_cpu(p, smp_processor_id());
|
|
|
|
/* CLONE_PARENT re-uses the old parent */
|
|
if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
|
|
p->real_parent = current->real_parent;
|
|
p->parent_exec_id = current->parent_exec_id;
|
|
} else {
|
|
p->real_parent = current;
|
|
p->parent_exec_id = current->self_exec_id;
|
|
}
|
|
|
|
spin_lock(¤t->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(¤t->sighand->siglock);
|
|
write_unlock_irq(&tasklist_lock);
|
|
retval = -ERESTARTNOINTR;
|
|
goto bad_fork_free_pid;
|
|
}
|
|
|
|
if (clone_flags & CLONE_THREAD) {
|
|
atomic_inc(¤t->signal->count);
|
|
atomic_inc(¤t->signal->live);
|
|
p->group_leader = current->group_leader;
|
|
list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
|
|
}
|
|
|
|
if (likely(p->pid)) {
|
|
list_add_tail(&p->sibling, &p->real_parent->children);
|
|
tracehook_finish_clone(p, clone_flags, trace);
|
|
|
|
if (thread_group_leader(p)) {
|
|
if (clone_flags & CLONE_NEWPID)
|
|
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));
|
|
list_add_tail_rcu(&p->tasks, &init_task.tasks);
|
|
__get_cpu_var(process_counts)++;
|
|
}
|
|
attach_pid(p, PIDTYPE_PID, pid);
|
|
nr_threads++;
|
|
}
|
|
|
|
total_forks++;
|
|
spin_unlock(¤t->sighand->siglock);
|
|
write_unlock_irq(&tasklist_lock);
|
|
proc_fork_connector(p);
|
|
cgroup_post_fork(p);
|
|
perf_counter_fork(p);
|
|
return p;
|
|
|
|
bad_fork_free_pid:
|
|
if (pid != &init_struct_pid)
|
|
free_pid(pid);
|
|
bad_fork_cleanup_io:
|
|
put_io_context(p->io_context);
|
|
bad_fork_cleanup_namespaces:
|
|
exit_task_namespaces(p);
|
|
bad_fork_cleanup_mm:
|
|
if (p->mm)
|
|
mmput(p->mm);
|
|
bad_fork_cleanup_signal:
|
|
if (!(clone_flags & CLONE_THREAD))
|
|
__cleanup_signal(p->signal);
|
|
bad_fork_cleanup_sighand:
|
|
__cleanup_sighand(p->sighand);
|
|
bad_fork_cleanup_fs:
|
|
exit_fs(p); /* blocking */
|
|
bad_fork_cleanup_files:
|
|
exit_files(p); /* blocking */
|
|
bad_fork_cleanup_semundo:
|
|
exit_sem(p);
|
|
bad_fork_cleanup_audit:
|
|
audit_free(p);
|
|
bad_fork_cleanup_policy:
|
|
perf_counter_free_task(p);
|
|
#ifdef CONFIG_NUMA
|
|
mpol_put(p->mempolicy);
|
|
bad_fork_cleanup_cgroup:
|
|
#endif
|
|
cgroup_exit(p, cgroup_callbacks_done);
|
|
delayacct_tsk_free(p);
|
|
if (p->binfmt)
|
|
module_put(p->binfmt->module);
|
|
bad_fork_cleanup_put_domain:
|
|
module_put(task_thread_info(p)->exec_domain->module);
|
|
bad_fork_cleanup_count:
|
|
atomic_dec(&p->cred->user->processes);
|
|
exit_creds(p);
|
|
bad_fork_free:
|
|
free_task(p);
|
|
fork_out:
|
|
return ERR_PTR(retval);
|
|
}
|
|
|
|
noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
|
|
{
|
|
memset(regs, 0, sizeof(struct pt_regs));
|
|
return regs;
|
|
}
|
|
|
|
struct task_struct * __cpuinit fork_idle(int cpu)
|
|
{
|
|
struct task_struct *task;
|
|
struct pt_regs regs;
|
|
|
|
task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
|
|
&init_struct_pid, 0);
|
|
if (!IS_ERR(task))
|
|
init_idle(task, cpu);
|
|
|
|
return task;
|
|
}
|
|
|
|
/*
|
|
* Ok, this is the main fork-routine.
|
|
*
|
|
* It copies the process, and if successful kick-starts
|
|
* it and waits for it to finish using the VM if required.
|
|
*/
|
|
long do_fork(unsigned long clone_flags,
|
|
unsigned long stack_start,
|
|
struct pt_regs *regs,
|
|
unsigned long stack_size,
|
|
int __user *parent_tidptr,
|
|
int __user *child_tidptr)
|
|
{
|
|
struct task_struct *p;
|
|
int trace = 0;
|
|
long nr;
|
|
|
|
/*
|
|
* Do some preliminary argument and permissions checking before we
|
|
* actually start allocating stuff
|
|
*/
|
|
if (clone_flags & CLONE_NEWUSER) {
|
|
if (clone_flags & CLONE_THREAD)
|
|
return -EINVAL;
|
|
/* hopefully this check will go away when userns support is
|
|
* complete
|
|
*/
|
|
if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) ||
|
|
!capable(CAP_SETGID))
|
|
return -EPERM;
|
|
}
|
|
|
|
/*
|
|
* We hope to recycle these flags after 2.6.26
|
|
*/
|
|
if (unlikely(clone_flags & CLONE_STOPPED)) {
|
|
static int __read_mostly count = 100;
|
|
|
|
if (count > 0 && printk_ratelimit()) {
|
|
char comm[TASK_COMM_LEN];
|
|
|
|
count--;
|
|
printk(KERN_INFO "fork(): process `%s' used deprecated "
|
|
"clone flags 0x%lx\n",
|
|
get_task_comm(comm, current),
|
|
clone_flags & CLONE_STOPPED);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* When called from kernel_thread, don't do user tracing stuff.
|
|
*/
|
|
if (likely(user_mode(regs)))
|
|
trace = tracehook_prepare_clone(clone_flags);
|
|
|
|
p = copy_process(clone_flags, stack_start, regs, stack_size,
|
|
child_tidptr, NULL, trace);
|
|
/*
|
|
* Do this prior waking up the new thread - the thread pointer
|
|
* might get invalid after that point, if the thread exits quickly.
|
|
*/
|
|
if (!IS_ERR(p)) {
|
|
struct completion vfork;
|
|
|
|
trace_sched_process_fork(current, p);
|
|
|
|
nr = task_pid_vnr(p);
|
|
|
|
if (clone_flags & CLONE_PARENT_SETTID)
|
|
put_user(nr, parent_tidptr);
|
|
|
|
if (clone_flags & CLONE_VFORK) {
|
|
p->vfork_done = &vfork;
|
|
init_completion(&vfork);
|
|
}
|
|
|
|
audit_finish_fork(p);
|
|
tracehook_report_clone(regs, clone_flags, nr, p);
|
|
|
|
/*
|
|
* We set PF_STARTING at creation in case tracing wants to
|
|
* use this to distinguish a fully live task from one that
|
|
* hasn't gotten to tracehook_report_clone() yet. Now we
|
|
* clear it and set the child going.
|
|
*/
|
|
p->flags &= ~PF_STARTING;
|
|
|
|
if (unlikely(clone_flags & CLONE_STOPPED)) {
|
|
/*
|
|
* We'll start up with an immediate SIGSTOP.
|
|
*/
|
|
sigaddset(&p->pending.signal, SIGSTOP);
|
|
set_tsk_thread_flag(p, TIF_SIGPENDING);
|
|
__set_task_state(p, TASK_STOPPED);
|
|
} else {
|
|
wake_up_new_task(p, clone_flags);
|
|
}
|
|
|
|
tracehook_report_clone_complete(trace, regs,
|
|
clone_flags, nr, p);
|
|
|
|
if (clone_flags & CLONE_VFORK) {
|
|
freezer_do_not_count();
|
|
wait_for_completion(&vfork);
|
|
freezer_count();
|
|
tracehook_report_vfork_done(p, nr);
|
|
}
|
|
} else {
|
|
nr = PTR_ERR(p);
|
|
}
|
|
return nr;
|
|
}
|
|
|
|
#ifndef ARCH_MIN_MMSTRUCT_ALIGN
|
|
#define ARCH_MIN_MMSTRUCT_ALIGN 0
|
|
#endif
|
|
|
|
static void sighand_ctor(void *data)
|
|
{
|
|
struct sighand_struct *sighand = data;
|
|
|
|
spin_lock_init(&sighand->siglock);
|
|
init_waitqueue_head(&sighand->signalfd_wqh);
|
|
}
|
|
|
|
void __init proc_caches_init(void)
|
|
{
|
|
sighand_cachep = kmem_cache_create("sighand_cache",
|
|
sizeof(struct sighand_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
|
|
SLAB_NOTRACK, sighand_ctor);
|
|
signal_cachep = kmem_cache_create("signal_cache",
|
|
sizeof(struct signal_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
|
|
files_cachep = kmem_cache_create("files_cache",
|
|
sizeof(struct files_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
|
|
fs_cachep = kmem_cache_create("fs_cache",
|
|
sizeof(struct fs_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
|
|
mm_cachep = kmem_cache_create("mm_struct",
|
|
sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
|
|
vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
|
|
mmap_init();
|
|
}
|
|
|
|
/*
|
|
* Check constraints on flags passed to the unshare system call and
|
|
* force unsharing of additional process context as appropriate.
|
|
*/
|
|
static void check_unshare_flags(unsigned long *flags_ptr)
|
|
{
|
|
/*
|
|
* If unsharing a thread from a thread group, must also
|
|
* unshare vm.
|
|
*/
|
|
if (*flags_ptr & CLONE_THREAD)
|
|
*flags_ptr |= CLONE_VM;
|
|
|
|
/*
|
|
* If unsharing vm, must also unshare signal handlers.
|
|
*/
|
|
if (*flags_ptr & CLONE_VM)
|
|
*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(¤t->signal->count) > 1))
|
|
*flags_ptr |= CLONE_THREAD;
|
|
|
|
/*
|
|
* If unsharing namespace, must also unshare filesystem information.
|
|
*/
|
|
if (*flags_ptr & CLONE_NEWNS)
|
|
*flags_ptr |= CLONE_FS;
|
|
}
|
|
|
|
/*
|
|
* Unsharing of tasks created with CLONE_THREAD is not supported yet
|
|
*/
|
|
static int unshare_thread(unsigned long unshare_flags)
|
|
{
|
|
if (unshare_flags & CLONE_THREAD)
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare the filesystem structure if it is being shared
|
|
*/
|
|
static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
|
|
{
|
|
struct fs_struct *fs = current->fs;
|
|
|
|
if (!(unshare_flags & CLONE_FS) || !fs)
|
|
return 0;
|
|
|
|
/* don't need lock here; in the worst case we'll do useless copy */
|
|
if (fs->users == 1)
|
|
return 0;
|
|
|
|
*new_fsp = copy_fs_struct(fs);
|
|
if (!*new_fsp)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unsharing of sighand is not supported yet
|
|
*/
|
|
static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)
|
|
{
|
|
struct sighand_struct *sigh = current->sighand;
|
|
|
|
if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1)
|
|
return -EINVAL;
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare vm if it is being shared
|
|
*/
|
|
static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
|
|
if ((unshare_flags & CLONE_VM) &&
|
|
(mm && atomic_read(&mm->mm_users) > 1)) {
|
|
return -EINVAL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare file descriptor table if it is being shared
|
|
*/
|
|
static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
|
|
{
|
|
struct files_struct *fd = current->files;
|
|
int error = 0;
|
|
|
|
if ((unshare_flags & CLONE_FILES) &&
|
|
(fd && atomic_read(&fd->count) > 1)) {
|
|
*new_fdp = dup_fd(fd, &error);
|
|
if (!*new_fdp)
|
|
return error;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* unshare allows a process to 'unshare' part of the process
|
|
* context which was originally shared using clone. copy_*
|
|
* functions used by do_fork() cannot be used here directly
|
|
* because they modify an inactive task_struct that is being
|
|
* constructed. Here we are modifying the current, active,
|
|
* task_struct.
|
|
*/
|
|
SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
|
|
{
|
|
int err = 0;
|
|
struct fs_struct *fs, *new_fs = NULL;
|
|
struct sighand_struct *new_sigh = NULL;
|
|
struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
|
|
struct files_struct *fd, *new_fd = NULL;
|
|
struct nsproxy *new_nsproxy = NULL;
|
|
int do_sysvsem = 0;
|
|
|
|
check_unshare_flags(&unshare_flags);
|
|
|
|
/* Return -EINVAL for all unsupported flags */
|
|
err = -EINVAL;
|
|
if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
|
|
CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
|
|
CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET))
|
|
goto bad_unshare_out;
|
|
|
|
/*
|
|
* CLONE_NEWIPC must also detach from the undolist: after switching
|
|
* to a new ipc namespace, the semaphore arrays from the old
|
|
* namespace are unreachable.
|
|
*/
|
|
if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
|
|
do_sysvsem = 1;
|
|
if ((err = unshare_thread(unshare_flags)))
|
|
goto bad_unshare_out;
|
|
if ((err = unshare_fs(unshare_flags, &new_fs)))
|
|
goto bad_unshare_cleanup_thread;
|
|
if ((err = unshare_sighand(unshare_flags, &new_sigh)))
|
|
goto bad_unshare_cleanup_fs;
|
|
if ((err = unshare_vm(unshare_flags, &new_mm)))
|
|
goto bad_unshare_cleanup_sigh;
|
|
if ((err = unshare_fd(unshare_flags, &new_fd)))
|
|
goto bad_unshare_cleanup_vm;
|
|
if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
|
|
new_fs)))
|
|
goto bad_unshare_cleanup_fd;
|
|
|
|
if (new_fs || new_mm || new_fd || do_sysvsem || new_nsproxy) {
|
|
if (do_sysvsem) {
|
|
/*
|
|
* CLONE_SYSVSEM is equivalent to sys_exit().
|
|
*/
|
|
exit_sem(current);
|
|
}
|
|
|
|
if (new_nsproxy) {
|
|
switch_task_namespaces(current, new_nsproxy);
|
|
new_nsproxy = NULL;
|
|
}
|
|
|
|
task_lock(current);
|
|
|
|
if (new_fs) {
|
|
fs = current->fs;
|
|
write_lock(&fs->lock);
|
|
current->fs = new_fs;
|
|
if (--fs->users)
|
|
new_fs = NULL;
|
|
else
|
|
new_fs = fs;
|
|
write_unlock(&fs->lock);
|
|
}
|
|
|
|
if (new_mm) {
|
|
mm = current->mm;
|
|
active_mm = current->active_mm;
|
|
current->mm = new_mm;
|
|
current->active_mm = new_mm;
|
|
activate_mm(active_mm, new_mm);
|
|
new_mm = mm;
|
|
}
|
|
|
|
if (new_fd) {
|
|
fd = current->files;
|
|
current->files = new_fd;
|
|
new_fd = fd;
|
|
}
|
|
|
|
task_unlock(current);
|
|
}
|
|
|
|
if (new_nsproxy)
|
|
put_nsproxy(new_nsproxy);
|
|
|
|
bad_unshare_cleanup_fd:
|
|
if (new_fd)
|
|
put_files_struct(new_fd);
|
|
|
|
bad_unshare_cleanup_vm:
|
|
if (new_mm)
|
|
mmput(new_mm);
|
|
|
|
bad_unshare_cleanup_sigh:
|
|
if (new_sigh)
|
|
if (atomic_dec_and_test(&new_sigh->count))
|
|
kmem_cache_free(sighand_cachep, new_sigh);
|
|
|
|
bad_unshare_cleanup_fs:
|
|
if (new_fs)
|
|
free_fs_struct(new_fs);
|
|
|
|
bad_unshare_cleanup_thread:
|
|
bad_unshare_out:
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Helper to unshare the files of the current task.
|
|
* We don't want to expose copy_files internals to
|
|
* the exec layer of the kernel.
|
|
*/
|
|
|
|
int unshare_files(struct files_struct **displaced)
|
|
{
|
|
struct task_struct *task = current;
|
|
struct files_struct *copy = NULL;
|
|
int error;
|
|
|
|
error = unshare_fd(CLONE_FILES, ©);
|
|
if (error || !copy) {
|
|
*displaced = NULL;
|
|
return error;
|
|
}
|
|
*displaced = task->files;
|
|
task_lock(task);
|
|
task->files = copy;
|
|
task_unlock(task);
|
|
return 0;
|
|
}
|