# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID 2fea03842f404f96955763caf803a29481953750
# Parent 5d4b9dc8821809768c2948f625e6f7e5597f4b5c
[LINUX] Eliminates a deadlock and reduce (sometimes significantly) the time
interrupts are off during context switch.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
linux-2.6-xen-sparse/arch/i386/mm/pgtable-xen.c | 6
linux-2.6-xen-sparse/arch/x86_64/mm/pageattr-xen.c | 6
linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/mmu.h | 4
linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/mmu_context.h | 11
linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/mmu.h | 4
linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/mmu_context.h | 12
linux-2.6-xen-sparse/kernel/fork.c | 1619
++++++++++
7 files changed, 1653 insertions(+), 9 deletions(-)
diff -r 5d4b9dc88218 -r 2fea03842f40
linux-2.6-xen-sparse/arch/i386/mm/pgtable-xen.c
--- a/linux-2.6-xen-sparse/arch/i386/mm/pgtable-xen.c Tue Jun 13 15:41:27
2006 +0100
+++ b/linux-2.6-xen-sparse/arch/i386/mm/pgtable-xen.c Tue Jun 13 15:56:28
2006 +0100
@@ -614,6 +614,12 @@ void mm_pin_all(void)
}
}
+void _arch_dup_mmap(struct mm_struct *mm)
+{
+ if (!test_bit(PG_pinned, &virt_to_page(mm->pgd)->flags))
+ mm_pin(mm);
+}
+
void _arch_exit_mmap(struct mm_struct *mm)
{
struct task_struct *tsk = current;
diff -r 5d4b9dc88218 -r 2fea03842f40
linux-2.6-xen-sparse/arch/x86_64/mm/pageattr-xen.c
--- a/linux-2.6-xen-sparse/arch/x86_64/mm/pageattr-xen.c Tue Jun 13
15:41:27 2006 +0100
+++ b/linux-2.6-xen-sparse/arch/x86_64/mm/pageattr-xen.c Tue Jun 13
15:56:28 2006 +0100
@@ -130,6 +130,12 @@ void mm_pin_all(void)
context.unpinned));
}
+void _arch_dup_mmap(struct mm_struct *mm)
+{
+ if (!mm->context.pinned)
+ mm_pin(mm);
+}
+
void _arch_exit_mmap(struct mm_struct *mm)
{
struct task_struct *tsk = current;
diff -r 5d4b9dc88218 -r 2fea03842f40
linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/mmu.h
--- a/linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/mmu.h Tue Jun 13
15:41:27 2006 +0100
+++ b/linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/mmu.h Tue Jun 13
15:56:28 2006 +0100
@@ -18,4 +18,8 @@ extern void _arch_exit_mmap(struct mm_st
extern void _arch_exit_mmap(struct mm_struct *mm);
#define arch_exit_mmap(_mm) _arch_exit_mmap(_mm)
+/* kernel/fork.c:dup_mmap hook */
+extern void _arch_dup_mmap(struct mm_struct *mm);
+#define arch_dup_mmap(mm, oldmm) ((void)(oldmm), _arch_dup_mmap(mm))
+
#endif
diff -r 5d4b9dc88218 -r 2fea03842f40
linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/mmu_context.h
--- a/linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/mmu_context.h Tue Jun
13 15:41:27 2006 +0100
+++ b/linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/mmu_context.h Tue Jun
13 15:56:28 2006 +0100
@@ -51,8 +51,7 @@ static inline void switch_mm(struct mm_s
struct mmuext_op _op[2], *op = _op;
if (likely(prev != next)) {
- if (!test_bit(PG_pinned, &virt_to_page(next->pgd)->flags))
- mm_pin(next);
+ BUG_ON(!test_bit(PG_pinned, &virt_to_page(next->pgd)->flags));
/* stop flush ipis for the previous mm */
cpu_clear(cpu, prev->cpu_vm_mask);
@@ -99,7 +98,11 @@ static inline void switch_mm(struct mm_s
#define deactivate_mm(tsk, mm) \
asm("movl %0,%%fs ; movl %0,%%gs": :"r" (0))
-#define activate_mm(prev, next) \
- switch_mm((prev),(next),NULL)
+static inline void activate_mm(struct mm_struct *prev, struct mm_struct *next)
+{
+ if (!test_bit(PG_pinned, &virt_to_page(next->pgd)->flags))
+ mm_pin(next);
+ switch_mm(prev, next, NULL);
+}
#endif
diff -r 5d4b9dc88218 -r 2fea03842f40
linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/mmu.h
--- a/linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/mmu.h Tue Jun
13 15:41:27 2006 +0100
+++ b/linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/mmu.h Tue Jun
13 15:56:28 2006 +0100
@@ -28,6 +28,10 @@ extern spinlock_t mm_unpinned_lock;
/* mm/memory.c:exit_mmap hook */
extern void _arch_exit_mmap(struct mm_struct *mm);
#define arch_exit_mmap(_mm) _arch_exit_mmap(_mm)
+
+/* kernel/fork.c:dup_mmap hook */
+extern void _arch_dup_mmap(struct mm_struct *mm);
+#define arch_dup_mmap(mm, oldmm) ((void)(oldmm), _arch_dup_mmap(mm))
#endif
#endif
diff -r 5d4b9dc88218 -r 2fea03842f40
linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/mmu_context.h
--- a/linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/mmu_context.h
Tue Jun 13 15:41:27 2006 +0100
+++ b/linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/mmu_context.h
Tue Jun 13 15:56:28 2006 +0100
@@ -73,8 +73,7 @@ static inline void switch_mm(struct mm_s
struct mmuext_op _op[3], *op = _op;
if (likely(prev != next)) {
- if (!next->context.pinned)
- mm_pin(next);
+ BUG_ON(!next->context.pinned);
/* stop flush ipis for the previous mm */
clear_bit(cpu, &prev->cpu_vm_mask);
@@ -127,8 +126,11 @@ static inline void switch_mm(struct mm_s
asm volatile("movl %0,%%fs"::"r"(0)); \
} while(0)
-#define activate_mm(prev, next) do { \
- switch_mm((prev),(next),NULL); \
-} while (0)
+static inline void activate_mm(struct mm_struct *prev, struct mm_struct *next)
+{
+ if (!next->context.pinned)
+ mm_pin(next);
+ switch_mm(prev, next, NULL);
+}
#endif
diff -r 5d4b9dc88218 -r 2fea03842f40 linux-2.6-xen-sparse/kernel/fork.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/linux-2.6-xen-sparse/kernel/fork.c Tue Jun 13 15:56:28 2006 +0100
@@ -0,0 +1,1619 @@
+/*
+ * linux/kernel/fork.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ */
+
+/*
+ * 'fork.c' contains the help-routines for the 'fork' system call
+ * (see also entry.S and others).
+ * Fork is rather simple, once you get the hang of it, but the memory
+ * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
+ */
+
+#include <linux/config.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/unistd.h>
+#include <linux/smp_lock.h>
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/completion.h>
+#include <linux/namespace.h>
+#include <linux/personality.h>
+#include <linux/mempolicy.h>
+#include <linux/sem.h>
+#include <linux/file.h>
+#include <linux/key.h>
+#include <linux/binfmts.h>
+#include <linux/mman.h>
+#include <linux/fs.h>
+#include <linux/capability.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/security.h>
+#include <linux/swap.h>
+#include <linux/syscalls.h>
+#include <linux/jiffies.h>
+#include <linux/futex.h>
+#include <linux/rcupdate.h>
+#include <linux/ptrace.h>
+#include <linux/mount.h>
+#include <linux/audit.h>
+#include <linux/profile.h>
+#include <linux/rmap.h>
+#include <linux/acct.h>
+#include <linux/cn_proc.h>
+
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/uaccess.h>
+#include <asm/mmu_context.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+
+/*
+ * Protected counters by write_lock_irq(&tasklist_lock)
+ */
+unsigned long total_forks; /* Handle normal Linux uptimes. */
+int nr_threads; /* The idle threads do not count.. */
+
+int max_threads; /* tunable limit on nr_threads */
+
+DEFINE_PER_CPU(unsigned long, process_counts) = 0;
+
+ __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
+
+EXPORT_SYMBOL(tasklist_lock);
+
+int nr_processes(void)
+{
+ int cpu;
+ int total = 0;
+
+ for_each_online_cpu(cpu)
+ total += per_cpu(process_counts, cpu);
+
+ return total;
+}
+
+#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
+# define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
+# define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
+static kmem_cache_t *task_struct_cachep;
+#endif
+
+/* SLAB cache for signal_struct structures (tsk->signal) */
+kmem_cache_t *signal_cachep;
+
+/* SLAB cache for sighand_struct structures (tsk->sighand) */
+kmem_cache_t *sighand_cachep;
+
+/* SLAB cache for files_struct structures (tsk->files) */
+kmem_cache_t *files_cachep;
+
+/* SLAB cache for fs_struct structures (tsk->fs) */
+kmem_cache_t *fs_cachep;
+
+/* SLAB cache for vm_area_struct structures */
+kmem_cache_t *vm_area_cachep;
+
+/* SLAB cache for mm_struct structures (tsk->mm) */
+static kmem_cache_t *mm_cachep;
+
+void free_task(struct task_struct *tsk)
+{
+ free_thread_info(tsk->thread_info);
+ free_task_struct(tsk);
+}
+EXPORT_SYMBOL(free_task);
+
+void __put_task_struct_cb(struct rcu_head *rhp)
+{
+ struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
+
+ WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
+ WARN_ON(atomic_read(&tsk->usage));
+ WARN_ON(tsk == current);
+
+ if (unlikely(tsk->audit_context))
+ audit_free(tsk);
+ security_task_free(tsk);
+ free_uid(tsk->user);
+ put_group_info(tsk->group_info);
+
+ if (!profile_handoff_task(tsk))
+ free_task(tsk);
+}
+
+void __init fork_init(unsigned long mempages)
+{
+#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
+#ifndef ARCH_MIN_TASKALIGN
+#define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
+#endif
+ /* create a slab on which task_structs can be allocated */
+ task_struct_cachep =
+ kmem_cache_create("task_struct", sizeof(struct task_struct),
+ ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL);
+#endif
+
+ /*
+ * The default maximum number of threads is set to a safe
+ * value: the thread structures can take up at most half
+ * of memory.
+ */
+ max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
+
+ /*
+ * we need to allow at least 20 threads to boot a system
+ */
+ if(max_threads < 20)
+ max_threads = 20;
+
+ init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
+ init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
+ init_task.signal->rlim[RLIMIT_SIGPENDING] =
+ init_task.signal->rlim[RLIMIT_NPROC];
+}
+
+static struct task_struct *dup_task_struct(struct task_struct *orig)
+{
+ struct task_struct *tsk;
+ struct thread_info *ti;
+
+ prepare_to_copy(orig);
+
+ tsk = alloc_task_struct();
+ if (!tsk)
+ return NULL;
+
+ ti = alloc_thread_info(tsk);
+ if (!ti) {
+ free_task_struct(tsk);
+ return NULL;
+ }
+
+ *tsk = *orig;
+ tsk->thread_info = ti;
+ setup_thread_stack(tsk, orig);
+
+ /* One for us, one for whoever does the "release_task()" (usually
parent) */
+ atomic_set(&tsk->usage,2);
+ atomic_set(&tsk->fs_excl, 0);
+ return tsk;
+}
+
+#ifdef CONFIG_MMU
+static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
+{
+ struct vm_area_struct *mpnt, *tmp, **pprev;
+ struct rb_node **rb_link, *rb_parent;
+ int retval;
+ unsigned long charge;
+ struct mempolicy *pol;
+
+ down_write(&oldmm->mmap_sem);
+ flush_cache_mm(oldmm);
+ down_write(&mm->mmap_sem);
+
+ mm->locked_vm = 0;
+ mm->mmap = NULL;
+ mm->mmap_cache = NULL;
+ mm->free_area_cache = oldmm->mmap_base;
+ mm->cached_hole_size = ~0UL;
+ mm->map_count = 0;
+ cpus_clear(mm->cpu_vm_mask);
+ mm->mm_rb = RB_ROOT;
+ rb_link = &mm->mm_rb.rb_node;
+ rb_parent = NULL;
+ pprev = &mm->mmap;
+
+ for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
+ struct file *file;
+
+ if (mpnt->vm_flags & VM_DONTCOPY) {
+ long pages = vma_pages(mpnt);
+ mm->total_vm -= pages;
+ vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
+ -pages);
+ continue;
+ }
+ charge = 0;
+ if (mpnt->vm_flags & VM_ACCOUNT) {
+ unsigned int len = (mpnt->vm_end - mpnt->vm_start) >>
PAGE_SHIFT;
+ if (security_vm_enough_memory(len))
+ goto fail_nomem;
+ charge = len;
+ }
+ tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
+ if (!tmp)
+ goto fail_nomem;
+ *tmp = *mpnt;
+ pol = mpol_copy(vma_policy(mpnt));
+ retval = PTR_ERR(pol);
+ if (IS_ERR(pol))
+ goto fail_nomem_policy;
+ vma_set_policy(tmp, pol);
+ tmp->vm_flags &= ~VM_LOCKED;
+ tmp->vm_mm = mm;
+ tmp->vm_next = NULL;
+ anon_vma_link(tmp);
+ file = tmp->vm_file;
+ if (file) {
+ struct inode *inode = file->f_dentry->d_inode;
+ get_file(file);
+ if (tmp->vm_flags & VM_DENYWRITE)
+ atomic_dec(&inode->i_writecount);
+
+ /* insert tmp into the share list, just after mpnt */
+ spin_lock(&file->f_mapping->i_mmap_lock);
+ tmp->vm_truncate_count = mpnt->vm_truncate_count;
+ flush_dcache_mmap_lock(file->f_mapping);
+ vma_prio_tree_add(tmp, mpnt);
+ flush_dcache_mmap_unlock(file->f_mapping);
+ spin_unlock(&file->f_mapping->i_mmap_lock);
+ }
+
+ /*
+ * Link in the new vma and copy the page table entries.
+ */
+ *pprev = tmp;
+ pprev = &tmp->vm_next;
+
+ __vma_link_rb(mm, tmp, rb_link, rb_parent);
+ rb_link = &tmp->vm_rb.rb_right;
+ rb_parent = &tmp->vm_rb;
+
+ mm->map_count++;
+ retval = copy_page_range(mm, oldmm, mpnt);
+
+ if (tmp->vm_ops && tmp->vm_ops->open)
+ tmp->vm_ops->open(tmp);
+
+ if (retval)
+ goto out;
+ }
+#ifdef arch_dup_mmap
+ arch_dup_mmap(mm, oldmm);
+#endif
+ retval = 0;
+out:
+ up_write(&mm->mmap_sem);
+ flush_tlb_mm(oldmm);
+ up_write(&oldmm->mmap_sem);
+ return retval;
+fail_nomem_policy:
+ kmem_cache_free(vm_area_cachep, tmp);
+fail_nomem:
+ retval = -ENOMEM;
+ vm_unacct_memory(charge);
+ goto out;
+}
+
+static inline int mm_alloc_pgd(struct mm_struct * mm)
+{
+ mm->pgd = pgd_alloc(mm);
+ if (unlikely(!mm->pgd))
+ return -ENOMEM;
+ return 0;
+}
+
+static inline void mm_free_pgd(struct mm_struct * mm)
+{
+ pgd_free(mm->pgd);
+}
+#else
+#define dup_mmap(mm, oldmm) (0)
+#define mm_alloc_pgd(mm) (0)
+#define mm_free_pgd(mm)
+#endif /* CONFIG_MMU */
+
+ __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
+
+#define allocate_mm() (kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
+#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
+
+#include <linux/init_task.h>
+
+static struct mm_struct * mm_init(struct mm_struct * mm)
+{
+ atomic_set(&mm->mm_users, 1);
+ atomic_set(&mm->mm_count, 1);
+ init_rwsem(&mm->mmap_sem);
+ INIT_LIST_HEAD(&mm->mmlist);
+ mm->core_waiters = 0;
+ 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);
+ rwlock_init(&mm->ioctx_list_lock);
+ mm->ioctx_list = NULL;
+ mm->free_area_cache = TASK_UNMAPPED_BASE;
+ mm->cached_hole_size = ~0UL;
+
+ if (likely(!mm_alloc_pgd(mm))) {
+ mm->def_flags = 0;
+ 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);
+ }
+ 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 fastcall __mmdrop(struct mm_struct *mm)
+{
+ BUG_ON(mm == &init_mm);
+ mm_free_pgd(mm);
+ destroy_context(mm);
+ free_mm(mm);
+}
+
+/*
+ * Decrement the use count and release all resources for an mm.
+ */
+void mmput(struct mm_struct *mm)
+{
+ if (atomic_dec_and_test(&mm->mm_users)) {
+ exit_aio(mm);
+ exit_mmap(mm);
+ 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_BORROWED_MM (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_BORROWED_MM)
+ 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 cached register state */
+ deactivate_mm(tsk, mm);
+
+ /* notify parent sleeping on vfork() */
+ if (vfork_done) {
+ tsk->vfork_done = NULL;
+ complete(vfork_done);
+ }
+ if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) {
+ u32 __user * tidptr = tsk->clear_child_tid;
+ tsk->clear_child_tid = NULL;
+
+ /*
+ * We don't check the error code - if userspace has
+ * not set up a proper pointer then tough luck.
+ */
+ put_user(0, tidptr);
+ sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
+ }
+}
+
+/*
+ * Allocate a new mm structure and copy contents from the
+ * mm structure of the passed in task structure.
+ */
+static 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));
+
+ if (!mm_init(mm))
+ goto fail_nomem;
+
+ if (init_new_context(tsk, mm))
+ goto fail_nocontext;
+
+ 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;
+
+ 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:
+ tsk->mm = mm;
+ tsk->active_mm = mm;
+ return 0;
+
+fail_nomem:
+ return retval;
+}
+
+static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
+{
+ struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
+ /* We don't need to lock fs - think why ;-) */
+ if (fs) {
+ atomic_set(&fs->count, 1);
+ rwlock_init(&fs->lock);
+ fs->umask = old->umask;
+ read_lock(&old->lock);
+ fs->rootmnt = mntget(old->rootmnt);
+ fs->root = dget(old->root);
+ fs->pwdmnt = mntget(old->pwdmnt);
+ fs->pwd = dget(old->pwd);
+ if (old->altroot) {
+ fs->altrootmnt = mntget(old->altrootmnt);
+ fs->altroot = dget(old->altroot);
+ } else {
+ fs->altrootmnt = NULL;
+ fs->altroot = NULL;
+ }
+ read_unlock(&old->lock);
+ }
+ return fs;
+}
+
+struct fs_struct *copy_fs_struct(struct fs_struct *old)
+{
+ return __copy_fs_struct(old);
+}
+
+EXPORT_SYMBOL_GPL(copy_fs_struct);
+
+static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
+{
+ if (clone_flags & CLONE_FS) {
+ atomic_inc(¤t->fs->count);
+ return 0;
+ }
+ tsk->fs = __copy_fs_struct(current->fs);
+ if (!tsk->fs)
+ return -ENOMEM;
+ return 0;
+}
+
+static int count_open_files(struct fdtable *fdt)
+{
+ int size = fdt->max_fdset;
+ int i;
+
+ /* Find the last open fd */
+ for (i = size/(8*sizeof(long)); i > 0; ) {
+ if (fdt->open_fds->fds_bits[--i])
+ break;
+ }
+ i = (i+1) * 8 * sizeof(long);
+ return i;
+}
+
+static struct files_struct *alloc_files(void)
+{
+ struct files_struct *newf;
+ struct fdtable *fdt;
+
+ newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
+ if (!newf)
+ goto out;
+
+ atomic_set(&newf->count, 1);
+
+ spin_lock_init(&newf->file_lock);
+ fdt = &newf->fdtab;
+ fdt->next_fd = 0;
+ fdt->max_fds = NR_OPEN_DEFAULT;
+ fdt->max_fdset = __FD_SETSIZE;
+ fdt->close_on_exec = &newf->close_on_exec_init;
+ fdt->open_fds = &newf->open_fds_init;
+ fdt->fd = &newf->fd_array[0];
+ INIT_RCU_HEAD(&fdt->rcu);
+ fdt->free_files = NULL;
+ fdt->next = NULL;
+ rcu_assign_pointer(newf->fdt, fdt);
+out:
+ return newf;
+}
+
+/*
+ * Allocate a new files structure and copy contents from the
+ * passed in files structure.
+ */
+static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
+{
+ struct files_struct *newf;
+ struct file **old_fds, **new_fds;
+ int open_files, size, i, expand;
+ struct fdtable *old_fdt, *new_fdt;
+
+ newf = alloc_files();
+ if (!newf)
+ goto out;
+
+ spin_lock(&oldf->file_lock);
+ old_fdt = files_fdtable(oldf);
+ new_fdt = files_fdtable(newf);
+ size = old_fdt->max_fdset;
+ open_files = count_open_files(old_fdt);
+ expand = 0;
+
+ /*
+ * Check whether we need to allocate a larger fd array or fd set.
+ * Note: we're not a clone task, so the open count won't change.
+ */
+ if (open_files > new_fdt->max_fdset) {
+ new_fdt->max_fdset = 0;
+ expand = 1;
+ }
+ if (open_files > new_fdt->max_fds) {
+ new_fdt->max_fds = 0;
+ expand = 1;
+ }
+
+ /* if the old fdset gets grown now, we'll only copy up to "size" fds */
+ if (expand) {
+ spin_unlock(&oldf->file_lock);
+ spin_lock(&newf->file_lock);
+ *errorp = expand_files(newf, open_files-1);
+ spin_unlock(&newf->file_lock);
+ if (*errorp < 0)
+ goto out_release;
+ new_fdt = files_fdtable(newf);
+ /*
+ * Reacquire the oldf lock and a pointer to its fd table
+ * who knows it may have a new bigger fd table. We need
+ * the latest pointer.
+ */
+ spin_lock(&oldf->file_lock);
+ old_fdt = files_fdtable(oldf);
+ }
+
+ old_fds = old_fdt->fd;
+ new_fds = new_fdt->fd;
+
+ memcpy(new_fdt->open_fds->fds_bits, old_fdt->open_fds->fds_bits,
open_files/8);
+ memcpy(new_fdt->close_on_exec->fds_bits,
old_fdt->close_on_exec->fds_bits, open_files/8);
+
+ for (i = open_files; i != 0; i--) {
+ struct file *f = *old_fds++;
+ if (f) {
+ get_file(f);
+ } else {
+ /*
+ * The fd may be claimed in the fd bitmap but not yet
+ * instantiated in the files array if a sibling thread
+ * is partway through open(). So make sure that this
+ * fd is available to the new process.
+ */
+ FD_CLR(open_files - i, new_fdt->open_fds);
+ }
+ rcu_assign_pointer(*new_fds++, f);
+ }
+ spin_unlock(&oldf->file_lock);
+
+ /* compute the remainder to be cleared */
+ size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
+
+ /* This is long word aligned thus could use a optimized version */
+ memset(new_fds, 0, size);
+
+ if (new_fdt->max_fdset > open_files) {
+ int left = (new_fdt->max_fdset-open_files)/8;
+ int start = open_files / (8 * sizeof(unsigned long));
+
+ memset(&new_fdt->open_fds->fds_bits[start], 0, left);
+ memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
+ }
+
+out:
+ return newf;
+
+out_release:
+ free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset);
+ free_fdset (new_fdt->open_fds, new_fdt->max_fdset);
+ free_fd_array(new_fdt->fd, new_fdt->max_fds);
+ kmem_cache_free(files_cachep, newf);
+ return NULL;
+}
+
+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;
+ }
+
+ /*
+ * Note: we may be using current for both targets (See exec.c)
+ * This works because we cache current->files (old) as oldf. Don't
+ * break this.
+ */
+ tsk->files = NULL;
+ error = -ENOMEM;
+ newf = dup_fd(oldf, &error);
+ if (!newf)
+ goto out;
+
+ tsk->files = newf;
+ error = 0;
+out:
+ return error;
+}
+
+/*
+ * 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(void)
+{
+ struct files_struct *files = current->files;
+ int rc;
+
+ if(!files)
+ BUG();
+
+ /* This can race but the race causes us to copy when we don't
+ need to and drop the copy */
+ if(atomic_read(&files->count) == 1)
+ {
+ atomic_inc(&files->count);
+ return 0;
+ }
+ rc = copy_files(0, current);
+ if(rc)
+ current->files = files;
+ return rc;
+}
+
+EXPORT_SYMBOL(unshare_files);
+
+void sighand_free_cb(struct rcu_head *rhp)
+{
+ struct sighand_struct *sp;
+
+ sp = container_of(rhp, struct sighand_struct, rcu);
+ kmem_cache_free(sighand_cachep, sp);
+}
+
+static inline int copy_sighand(unsigned long clone_flags, struct task_struct *
tsk)
+{
+ struct sighand_struct *sig;
+
+ if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
+ 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;
+ spin_lock_init(&sig->siglock);
+ atomic_set(&sig->count, 1);
+ memcpy(sig->action, current->sighand->action, sizeof(sig->action));
+ return 0;
+}
+
+static inline int copy_signal(unsigned long clone_flags, struct task_struct *
tsk)
+{
+ struct signal_struct *sig;
+ int ret;
+
+ if (clone_flags & CLONE_THREAD) {
+ atomic_inc(¤t->signal->count);
+ atomic_inc(¤t->signal->live);
+ return 0;
+ }
+ sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
+ tsk->signal = sig;
+ if (!sig)
+ return -ENOMEM;
+
+ ret = copy_thread_group_keys(tsk);
+ if (ret < 0) {
+ kmem_cache_free(signal_cachep, sig);
+ return ret;
+ }
+
+ atomic_set(&sig->count, 1);
+ atomic_set(&sig->live, 1);
+ init_waitqueue_head(&sig->wait_chldexit);
+ sig->flags = 0;
+ sig->group_exit_code = 0;
+ sig->group_exit_task = NULL;
+ sig->group_stop_count = 0;
+ sig->curr_target = NULL;
+ init_sigpending(&sig->shared_pending);
+ INIT_LIST_HEAD(&sig->posix_timers);
+
+ hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_REL);
+ sig->it_real_incr.tv64 = 0;
+ sig->real_timer.function = it_real_fn;
+ sig->real_timer.data = tsk;
+
+ sig->it_virt_expires = cputime_zero;
+ sig->it_virt_incr = cputime_zero;
+ sig->it_prof_expires = cputime_zero;
+ sig->it_prof_incr = cputime_zero;
+
+ sig->leader = 0; /* session leadership doesn't inherit */
+ sig->tty_old_pgrp = 0;
+
+ sig->utime = sig->stime = sig->cutime = sig->cstime = 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->sched_time = 0;
+ INIT_LIST_HEAD(&sig->cpu_timers[0]);
+ INIT_LIST_HEAD(&sig->cpu_timers[1]);
+ INIT_LIST_HEAD(&sig->cpu_timers[2]);
+
+ task_lock(current->group_leader);
+ memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
+ task_unlock(current->group_leader);
+
+ if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
+ /*
+ * New sole thread in the process gets an expiry time
+ * of the whole CPU time limit.
+ */
+ tsk->it_prof_expires =
+ secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
+ }
+
+ return 0;
+}
+
+static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
+{
+ unsigned long new_flags = p->flags;
+
+ new_flags &= ~(PF_SUPERPRIV | PF_NOFREEZE);
+ new_flags |= PF_FORKNOEXEC;
+ if (!(clone_flags & CLONE_PTRACE))
+ p->ptrace = 0;
+ p->flags = new_flags;
+}
+
+asmlinkage long sys_set_tid_address(int __user *tidptr)
+{
+ current->clear_child_tid = tidptr;
+
+ return current->pid;
+}
+
+/*
+ * 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 task_t *copy_process(unsigned long clone_flags,
+ unsigned long stack_start,
+ struct pt_regs *regs,
+ unsigned long stack_size,
+ int __user *parent_tidptr,
+ int __user *child_tidptr,
+ int pid)
+{
+ int retval;
+ struct task_struct *p = NULL;
+
+ 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;
+
+ retval = -EAGAIN;
+ if (atomic_read(&p->user->processes) >=
+ p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
+ if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
+ p->user != &root_user)
+ goto bad_fork_free;
+ }
+
+ atomic_inc(&p->user->__count);
+ atomic_inc(&p->user->processes);
+ get_group_info(p->group_info);
+
+ /*
+ * 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.
+ */
+ 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;
+ copy_flags(clone_flags, p);
+ p->pid = pid;
+ retval = -EFAULT;
+ if (clone_flags & CLONE_PARENT_SETTID)
+ if (put_user(p->pid, parent_tidptr))
+ goto bad_fork_cleanup;
+
+ p->proc_dentry = NULL;
+
+ INIT_LIST_HEAD(&p->children);
+ INIT_LIST_HEAD(&p->sibling);
+ p->vfork_done = NULL;
+ spin_lock_init(&p->alloc_lock);
+ spin_lock_init(&p->proc_lock);
+
+ clear_tsk_thread_flag(p, TIF_SIGPENDING);
+ init_sigpending(&p->pending);
+
+ p->utime = cputime_zero;
+ p->stime = cputime_zero;
+ p->sched_time = 0;
+ p->rchar = 0; /* I/O counter: bytes read */
+ p->wchar = 0; /* I/O counter: bytes written */
+ p->syscr = 0; /* I/O counter: read syscalls */
+ p->syscw = 0; /* I/O counter: write syscalls */
+ acct_clear_integrals(p);
+
+ p->it_virt_expires = cputime_zero;
+ p->it_prof_expires = cputime_zero;
+ p->it_sched_expires = 0;
+ INIT_LIST_HEAD(&p->cpu_timers[0]);
+ INIT_LIST_HEAD(&p->cpu_timers[1]);
+ INIT_LIST_HEAD(&p->cpu_timers[2]);
+
+ p->lock_depth = -1; /* -1 = no lock */
+ do_posix_clock_monotonic_gettime(&p->start_time);
+ p->security = NULL;
+ p->io_context = NULL;
+ p->io_wait = NULL;
+ p->audit_context = NULL;
+ cpuset_fork(p);
+#ifdef CONFIG_NUMA
+ p->mempolicy = mpol_copy(p->mempolicy);
+ if (IS_ERR(p->mempolicy)) {
+ retval = PTR_ERR(p->mempolicy);
+ p->mempolicy = NULL;
+ goto bad_fork_cleanup_cpuset;
+ }
+#endif
+
+#ifdef CONFIG_DEBUG_MUTEXES
+ p->blocked_on = NULL; /* not blocked yet */
+#endif
+
+ p->tgid = p->pid;
+ if (clone_flags & CLONE_THREAD)
+ p->tgid = current->tgid;
+
+ if ((retval = security_task_alloc(p)))
+ goto bad_fork_cleanup_policy;
+ if ((retval = audit_alloc(p)))
+ goto bad_fork_cleanup_security;
+ /* 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_keys(clone_flags, p)))
+ goto bad_fork_cleanup_mm;
+ if ((retval = copy_namespace(clone_flags, p)))
+ goto bad_fork_cleanup_keys;
+ retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
+ if (retval)
+ goto bad_fork_cleanup_namespace;
+
+ 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;
+
+ /*
+ * 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
+
+ /* Our parent execution domain becomes current domain
+ These must match for thread signalling to apply */
+
+ p->parent_exec_id = p->self_exec_id;
+
+ /* 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->ptrace_children);
+ INIT_LIST_HEAD(&p->ptrace_list);
+
+ /* Perform scheduler related setup. Assign this task to a CPU. */
+ sched_fork(p, clone_flags);
+
+ /* 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;
+ if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
+ !cpu_online(task_cpu(p))))
+ set_task_cpu(p, smp_processor_id());
+
+ /*
+ * Check for pending SIGKILL! The new thread should not be allowed
+ * to slip out of an OOM kill. (or normal SIGKILL.)
+ */
+ if (sigismember(¤t->pending.signal, SIGKILL)) {
+ write_unlock_irq(&tasklist_lock);
+ retval = -EINTR;
+ goto bad_fork_cleanup_namespace;
+ }
+
+ /* CLONE_PARENT re-uses the old parent */
+ if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
+ p->real_parent = current->real_parent;
+ else
+ p->real_parent = current;
+ p->parent = p->real_parent;
+
+ spin_lock(¤t->sighand->siglock);
+ if (clone_flags & CLONE_THREAD) {
+ /*
+ * Important: if an exit-all has been started then
+ * do not create this new thread - the whole thread
+ * group is supposed to exit anyway.
+ */
+ if (current->signal->flags & SIGNAL_GROUP_EXIT) {
+ spin_unlock(¤t->sighand->siglock);
+ write_unlock_irq(&tasklist_lock);
+ retval = -EAGAIN;
+ goto bad_fork_cleanup_namespace;
+ }
+ p->group_leader = current->group_leader;
+
+ if (current->signal->group_stop_count > 0) {
+ /*
+ * There is an all-stop in progress for the group.
+ * We ourselves will stop as soon as we check signals.
+ * Make the new thread part of that group stop too.
+ */
+ current->signal->group_stop_count++;
+ set_tsk_thread_flag(p, TIF_SIGPENDING);
+ }
+
+ if (!cputime_eq(current->signal->it_virt_expires,
+ cputime_zero) ||
+ !cputime_eq(current->signal->it_prof_expires,
+ cputime_zero) ||
+ current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY
||
+ !list_empty(¤t->signal->cpu_timers[0]) ||
+ !list_empty(¤t->signal->cpu_timers[1]) ||
+ !list_empty(¤t->signal->cpu_timers[2])) {
+ /*
+ * Have child wake up on its first tick to check
+ * for process CPU timers.
+ */
+ p->it_prof_expires = jiffies_to_cputime(1);
+ }
+ }
+
+ /*
+ * inherit ioprio
+ */
+ p->ioprio = current->ioprio;
+
+ SET_LINKS(p);
+ if (unlikely(p->ptrace & PT_PTRACED))
+ __ptrace_link(p, current->parent);
+
+ if (thread_group_leader(p)) {
+ p->signal->tty = current->signal->tty;
+ p->signal->pgrp = process_group(current);
+ p->signal->session = current->signal->session;
+ attach_pid(p, PIDTYPE_PGID, process_group(p));
+ attach_pid(p, PIDTYPE_SID, p->signal->session);
+ if (p->pid)
+ __get_cpu_var(process_counts)++;
+ }
+ attach_pid(p, PIDTYPE_TGID, p->tgid);
+ attach_pid(p, PIDTYPE_PID, p->pid);
+
+ nr_threads++;
+ total_forks++;
+ spin_unlock(¤t->sighand->siglock);
+ write_unlock_irq(&tasklist_lock);
+ proc_fork_connector(p);
+ return p;
+
+bad_fork_cleanup_namespace:
+ exit_namespace(p);
+bad_fork_cleanup_keys:
+ exit_keys(p);
+bad_fork_cleanup_mm:
+ if (p->mm)
+ mmput(p->mm);
+bad_fork_cleanup_signal:
+ exit_signal(p);
+bad_fork_cleanup_sighand:
+ exit_sighand(p);
+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_security:
+ security_task_free(p);
+bad_fork_cleanup_policy:
+#ifdef CONFIG_NUMA
+ mpol_free(p->mempolicy);
+bad_fork_cleanup_cpuset:
+#endif
+ cpuset_exit(p);
+bad_fork_cleanup:
+ 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:
+ put_group_info(p->group_info);
+ atomic_dec(&p->user->processes);
+ free_uid(p->user);
+bad_fork_free:
+ free_task(p);
+fork_out:
+ return ERR_PTR(retval);
+}
+
+struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs
*regs)
+{
+ memset(regs, 0, sizeof(struct pt_regs));
+ return regs;
+}
+
+task_t * __devinit fork_idle(int cpu)
+{
+ task_t *task;
+ struct pt_regs regs;
+
+ task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, NULL, 0);
+ if (!task)
+ return ERR_PTR(-ENOMEM);
+ init_idle(task, cpu);
+ unhash_process(task);
+ return task;
+}
+
+static inline int fork_traceflag (unsigned clone_flags)
+{
+ if (clone_flags & CLONE_UNTRACED)
+ return 0;
+ else if (clone_flags & CLONE_VFORK) {
+ if (current->ptrace & PT_TRACE_VFORK)
+ return PTRACE_EVENT_VFORK;
+ } else if ((clone_flags & CSIGNAL) != SIGCHLD) {
+ if (current->ptrace & PT_TRACE_CLONE)
+ return PTRACE_EVENT_CLONE;
+ } else if (current->ptrace & PT_TRACE_FORK)
+ return PTRACE_EVENT_FORK;
+
+ return 0;
+}
+
+/*
+ * 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 pid = alloc_pidmap();
+
+ if (pid < 0)
+ return -EAGAIN;
+ if (unlikely(current->ptrace)) {
+ trace = fork_traceflag (clone_flags);
+ if (trace)
+ clone_flags |= CLONE_PTRACE;
+ }
+
+ p = copy_process(clone_flags, stack_start, regs, stack_size,
parent_tidptr, child_tidptr, pid);
+ /*
+ * 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;
+
+ if (clone_flags & CLONE_VFORK) {
+ p->vfork_done = &vfork;
+ init_completion(&vfork);
+ }
+
+ if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
+ /*
+ * We'll start up with an immediate SIGSTOP.
+ */
+ sigaddset(&p->pending.signal, SIGSTOP);
+ set_tsk_thread_flag(p, TIF_SIGPENDING);
+ }
+
+ if (!(clone_flags & CLONE_STOPPED))
+ wake_up_new_task(p, clone_flags);
+ else
+ p->state = TASK_STOPPED;
+
+ if (unlikely (trace)) {
+ current->ptrace_message = pid;
+ ptrace_notify ((trace << 8) | SIGTRAP);
+ }
+
+ if (clone_flags & CLONE_VFORK) {
+ wait_for_completion(&vfork);
+ if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
+ ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) |
SIGTRAP);
+ }
+ } else {
+ free_pidmap(pid);
+ pid = PTR_ERR(p);
+ }
+ return pid;
+}
+
+#ifndef ARCH_MIN_MMSTRUCT_ALIGN
+#define ARCH_MIN_MMSTRUCT_ALIGN 0
+#endif
+
+void __init proc_caches_init(void)
+{
+ sighand_cachep = kmem_cache_create("sighand_cache",
+ sizeof(struct sighand_struct), 0,
+ SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+ signal_cachep = kmem_cache_create("signal_cache",
+ sizeof(struct signal_struct), 0,
+ SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+ files_cachep = kmem_cache_create("files_cache",
+ sizeof(struct files_struct), 0,
+ SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+ fs_cachep = kmem_cache_create("fs_cache",
+ sizeof(struct fs_struct), 0,
+ SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+ vm_area_cachep = kmem_cache_create("vm_area_struct",
+ sizeof(struct vm_area_struct), 0,
+ SLAB_PANIC, NULL, NULL);
+ mm_cachep = kmem_cache_create("mm_struct",
+ sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
+ SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+}
+
+
+/*
+ * Check constraints on flags passed to the unshare system call and
+ * force unsharing of additional process context as appropriate.
+ */
+static inline 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 && atomic_read(&fs->count) > 1)) {
+ *new_fsp = __copy_fs_struct(current->fs);
+ if (!*new_fsp)
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+/*
+ * Unshare the namespace structure if it is being shared
+ */
+static int unshare_namespace(unsigned long unshare_flags, struct namespace
**new_nsp, struct fs_struct *new_fs)
+{
+ struct namespace *ns = current->namespace;
+
+ if ((unshare_flags & CLONE_NEWNS) &&
+ (ns && atomic_read(&ns->count) > 1)) {
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ *new_nsp = dup_namespace(current, new_fs ? new_fs :
current->fs);
+ if (!*new_nsp)
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+/*
+ * Unsharing of sighand for tasks created with CLONE_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) &&
+ (sigh && 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;
+}
+
+/*
+ * Unsharing of semundo for tasks created with CLONE_SYSVSEM is not
+ * supported yet
+ */
+static int unshare_semundo(unsigned long unshare_flags, struct sem_undo_list
**new_ulistp)
+{
+ if (unshare_flags & CLONE_SYSVSEM)
+ return -EINVAL;
+
+ 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.
+ */
+asmlinkage long sys_unshare(unsigned long unshare_flags)
+{
+ int err = 0;
+ struct fs_struct *fs, *new_fs = NULL;
+ struct namespace *ns, *new_ns = NULL;
+ struct sighand_struct *sigh, *new_sigh = NULL;
+ struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
+ struct files_struct *fd, *new_fd = NULL;
+ struct sem_undo_list *new_ulist = NULL;
+
+ check_unshare_flags(&unshare_flags);
+
+ 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_namespace(unshare_flags, &new_ns, new_fs)))
+ goto bad_unshare_cleanup_fs;
+ if ((err = unshare_sighand(unshare_flags, &new_sigh)))
+ goto bad_unshare_cleanup_ns;
+ 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_semundo(unshare_flags, &new_ulist)))
+ goto bad_unshare_cleanup_fd;
+
+ if (new_fs || new_ns || new_sigh || new_mm || new_fd || new_ulist) {
+
+ task_lock(current);
+
+ if (new_fs) {
+ fs = current->fs;
+ current->fs = new_fs;
+ new_fs = fs;
+ }
+
+ if (new_ns) {
+ ns = current->namespace;
+ current->namespace = new_ns;
+ new_ns = ns;
+ }
+
+ if (new_sigh) {
+ sigh = current->sighand;
+ rcu_assign_pointer(current->sighand, new_sigh);
+ new_sigh = sigh;
+ }
+
+ 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);
+ }
+
+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_ns:
+ if (new_ns)
+ put_namespace(new_ns);
+
+bad_unshare_cleanup_fs:
+ if (new_fs)
+ put_fs_struct(new_fs);
+
+bad_unshare_cleanup_thread:
+bad_unshare_out:
+ return err;
+}
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