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    Subject[PATCH 10/16] Changes in copy_process() to work with pid namespaces
    We must pass the namespace pointer to the alloc_pid() to
    show what namespace to allocate the pid from and we should
    call this *after* the namespace is copied.

    Essentially, the task->pid etc initialization is done after
    the alloc_pid().

    To do so I move the alloc_pid() inside copy_process() and
    introduce an argument to the alloc_pid() function.

    Signed-off-by: Pavel Emelianov <xemul@openvz.org>

    ---

    include/linux/pid.h | 2 +-
    kernel/fork.c | 29 +++++++++++++++++------------
    kernel/pid.c | 2 +-
    3 files changed, 19 insertions(+), 14 deletions(-)

    --- ./include/linux/pid.h.ve9 2007-07-06 11:03:55.000000000 +0400
    +++ ./include/linux/pid.h 2007-07-06 11:03:55.000000000 +0400
    @@ -116,7 +116,7 @@ extern struct pid *FASTCALL(find_pid_ns(
    extern struct pid *find_get_pid(int nr);
    extern struct pid *find_ge_pid(int nr, struct pid_namespace *);

    -extern struct pid *alloc_pid(void);
    +extern struct pid *alloc_pid(struct pid_namespace *ns);
    extern void FASTCALL(free_pid(struct pid *pid));

    /*
    --- ./kernel/fork.c.ve9 2007-07-06 11:03:55.000000000 +0400
    +++ ./kernel/fork.c 2007-07-06 11:04:07.000000000 +0400
    @@ -50,6 +50,7 @@
    #include <linux/taskstats_kern.h>
    #include <linux/random.h>
    #include <linux/tty.h>
    +#include <linux/pid.h>

    #include <asm/pgtable.h>
    #include <asm/pgalloc.h>
    @@ -1032,7 +1033,6 @@ static struct task_struct *copy_process(
    p->did_exec = 0;
    delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
    copy_flags(clone_flags, p);
    - p->pid = pid_nr(pid);
    INIT_LIST_HEAD(&p->children);
    INIT_LIST_HEAD(&p->sibling);
    p->vfork_done = NULL;
    @@ -1107,10 +1107,6 @@ static struct task_struct *copy_process(
    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)))
    @@ -1132,9 +1128,14 @@ static struct task_struct *copy_process(
    goto bad_fork_cleanup_mm;
    if ((retval = copy_namespaces(clone_flags, p)))
    goto bad_fork_cleanup_keys;
    + if (likely(pid == NULL)) {
    + pid = alloc_pid(p->nsproxy->pid_ns);
    + if (pid == NULL)
    + goto bad_fork_cleanup_namespaces;
    + }
    retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
    if (retval)
    - goto bad_fork_cleanup_namespaces;
    + goto bad_fork_cleanup_pid;

    p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
    /*
    @@ -1255,6 +1256,11 @@ static struct task_struct *copy_process(
    }
    }

    + p->pid = pid_nr(pid);
    + p->tgid = p->pid;
    + if (clone_flags & CLONE_THREAD)
    + p->tgid = current->tgid;
    +
    if (likely(p->pid)) {
    add_parent(p);
    if (unlikely(p->ptrace & PT_PTRACED))
    @@ -1288,6 +1294,8 @@ static struct task_struct *copy_process(
    proc_fork_connector(p);
    return p;

    +bad_fork_cleanup_pid:
    + free_pid(pid);
    bad_fork_cleanup_namespaces:
    exit_task_namespaces(p);
    bad_fork_cleanup_keys:
    @@ -1380,19 +1388,16 @@ long do_fork(unsigned long clone_flags,
    {
    struct task_struct *p;
    int trace = 0;
    - struct pid *pid = alloc_pid();
    long nr;

    - if (!pid)
    - return -EAGAIN;
    - nr = pid->nr;
    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);
    + p = copy_process(clone_flags, stack_start, regs, stack_size,
    + parent_tidptr, child_tidptr, NULL);
    /*
    * Do this prior waking up the new thread - the thread pointer
    * might get invalid after that point, if the thread exits quickly.
    @@ -1418,6 +1423,7 @@ long do_fork(unsigned long clone_flags,
    else
    p->state = TASK_STOPPED;

    + nr = pid_vnr(task_pid(p));
    if (unlikely (trace)) {
    current->ptrace_message = nr;
    ptrace_notify ((trace << 8) | SIGTRAP);
    @@ -1433,7 +1439,6 @@ long do_fork(unsigned long clone_flags,
    }
    }
    } else {
    - free_pid(pid);
    nr = PTR_ERR(p);
    }
    return nr;
    --- ./kernel/pid.c.ve9 2007-07-06 11:03:55.000000000 +0400
    +++ ./kernel/pid.c 2007-07-06 11:03:55.000000000 +0400
    @@ -206,7 +206,7 @@ fastcall void free_pid(struct pid *pid)
    call_rcu(&pid->rcu, delayed_put_pid);
    }

    -struct pid *alloc_pid(void)
    +struct pid *alloc_pid(struct pid_namespace *pid_ns)
    {
    struct pid *pid;
    enum pid_type type;
    -
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