[PATCH 5/5] Move alloc_pid() to copy_process()

sukadev
2007-07-15T04:59:16Z

Pavel

Like we discussed, I am sending this out. Pls ack.

Suka
---

Subject: [PATCH 5/5] Move alloc_pid call to copy_process

From: Sukadev Bhattiprolu <sukadev@us.ibm.com>

Move alloc_pid() into copy_process(). This will keep all pid and pid
namespace code together and simplify error handling when we support
multiple pid namespaces.

Changelog:
- [Eric Biederman] Move the check of copy_process_type to alloc_pid()/
free_pid() and to avoid clutter in copy_process().

Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>

Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Herbert Poetzel <herbert@13thfloor.at>
---
include/linux/pid.h | 7 ++++++-
kernel/fork.c | 21 +++++++++++++--------
kernel/pid.c | 10 +++++++++-
3 files changed, 28 insertions(+), 10 deletions(-)

Index: lx26-22-rc6-mm1/include/linux/pid.h
===================================================================
--- lx26-22-rc6-mm1.orig/include/linux/pid.h 2007-07-13 18:13:38.000000000 -0700
+++ lx26-22-rc6-mm1/include/linux/pid.h 2007-07-13 18:23:55.000000000 -0700
@@ -3,6 +3,11 @@

#include <linux/rcupdate.h>

+enum copy_process_type {
+ COPY_NON_IDLE_PROCESS,
+ COPY_IDLE_PROCESS,
+};
+
enum pid_type
{
PIDTYPE_PID,
@@ -95,7 +100,7 @@ extern struct pid *FASTCALL(find_pid(int
extern struct pid *find_get_pid(int nr);
extern struct pid *find_ge_pid(int nr);

-extern struct pid *alloc_pid(void);
+extern struct pid *alloc_pid(enum copy_process_type);
extern void FASTCALL(free_pid(struct pid *pid));

static inline pid_t pid_nr(struct pid *pid)
Index: lx26-22-rc6-mm1/kernel/fork.c
===================================================================
--- lx26-22-rc6-mm1.orig/kernel/fork.c 2007-07-13 18:13:38.000000000 -0700
+++ lx26-22-rc6-mm1/kernel/fork.c 2007-07-13 18:23:55.000000000 -0700
@@ -964,11 +964,12 @@ static struct task_struct *copy_process(
unsigned long stack_size,
int __user *parent_tidptr,
int __user *child_tidptr,
- struct pid *pid)
+ enum copy_process_type copy_src)
{
int retval;
struct task_struct *p = NULL;
int container_callbacks_done = 0;
+ struct pid *pid;

if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
return ERR_PTR(-EINVAL);
@@ -1029,6 +1030,10 @@ static struct task_struct *copy_process(
if (p->binfmt && !try_module_get(p->binfmt->module))
goto bad_fork_cleanup_put_domain;

+ pid = alloc_pid(copy_src);
+ if (!pid)
+ goto bad_fork_put_binfmt_module;
+
p->did_exec = 0;
delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
copy_flags(clone_flags, p);
@@ -1316,6 +1321,8 @@ bad_fork_cleanup_container:
#endif
container_exit(p, container_callbacks_done);
delayacct_tsk_free(p);
+ free_pid(pid);
+bad_fork_put_binfmt_module:
if (p->binfmt)
module_put(p->binfmt->module);
bad_fork_cleanup_put_domain:
@@ -1342,7 +1349,7 @@ struct task_struct * __cpuinit fork_idle
struct pt_regs regs;

task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL, NULL,
- &init_struct_pid);
+ COPY_IDLE_PROCESS);
if (!IS_ERR(task))
init_idle(task, cpu);

@@ -1380,19 +1387,16 @@ 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, COPY_NON_IDLE_PROCESS);
/*
* Do this prior waking up the new thread - the thread pointer
* might get invalid after that point, if the thread exits quickly.
@@ -1400,6 +1404,8 @@ long do_fork(unsigned long clone_flags,
if (!IS_ERR(p)) {
struct completion vfork;

+ nr = pid_nr(task_pid(p));
+
if (clone_flags & CLONE_VFORK) {
p->vfork_done = &vfork;
init_completion(&vfork);
@@ -1433,7 +1439,6 @@ long do_fork(unsigned long clone_flags,
}
}
} else {
- free_pid(pid);
nr = PTR_ERR(p);
}
return nr;
Index: lx26-22-rc6-mm1/kernel/pid.c
===================================================================
--- lx26-22-rc6-mm1.orig/kernel/pid.c 2007-07-13 18:23:55.000000000 -0700
+++ lx26-22-rc6-mm1/kernel/pid.c 2007-07-13 18:23:55.000000000 -0700
@@ -206,6 +206,10 @@ fastcall void free_pid(struct pid *pid)
/* We can be called with write_lock_irq(&tasklist_lock) held */
unsigned long flags;

+ /* check this here to keep copy_process() cleaner */
+ if (unlikely(pid == &init_struct_pid))
+ return;
+
spin_lock_irqsave(&pidmap_lock, flags);
hlist_del_rcu(&pid->pid_chain);
spin_unlock_irqrestore(&pidmap_lock, flags);
@@ -214,13 +218,17 @@ fastcall void free_pid(struct pid *pid)
call_rcu(&pid->rcu, delayed_put_pid);
}

-struct pid *alloc_pid(void)
+struct pid *alloc_pid(enum copy_process_type copy_src)
{
struct pid *pid;
enum pid_type type;
int nr = -1;
struct pid_namespace *ns;

+ /* check this here to keep copy_process() cleaner */
+ if (unlikely(copy_src == COPY_IDLE_PROCESS))
+ return &init_struct_pid;
+
ns = task_active_pid_ns(current);
pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
if (!pid)