[PATCH 10/16] Changes in copy_process() to work with pid namespaces

Pavel Emelianov
2007-07-06T08:10:23Z

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;