From 2894d650cd9715d00ca196c711265819ef6ebd2d Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Thu, 18 Oct 2007 23:39:49 -0700 Subject: [PATCH] pid namespaces: define and use task_active_pid_ns() wrapper With multiple pid namespaces, a process is known by some pid_t in every ancestor pid namespace. Every time the process forks, the child process also gets a pid_t in every ancestor pid namespace. While a process is visible in >=1 pid namespaces, it can see pid_t's in only one pid namespace. We call this pid namespace it's "active pid namespace", and it is always the youngest pid namespace in which the process is known. This patch defines and uses a wrapper to find the active pid namespace of a process. The implementation of the wrapper will be changed in when support for multiple pid namespaces are added. Changelog: 2.6.22-rc4-mm2-pidns1: - [Pavel Emelianov, Alexey Dobriyan] Back out the change to use task_active_pid_ns() in child_reaper() since task->nsproxy can be NULL during task exit (so child_reaper() continues to use init_pid_ns). to implement child_reaper() since init_pid_ns.child_reaper to implement child_reaper() since tsk->nsproxy can be NULL during exit. 2.6.21-rc6-mm1: - Rename task_pid_ns() to task_active_pid_ns() to reflect that a process can have multiple pid namespaces. Signed-off-by: Sukadev Bhattiprolu Acked-by: Pavel Emelianov Cc: Eric W. Biederman Cc: Cedric Le Goater Cc: Dave Hansen Cc: Serge Hallyn Cc: Herbert Poetzel Cc: Kirill Korotaev Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/exec.c | 2 +- fs/proc/proc_misc.c | 3 ++- include/linux/pid_namespace.h | 5 +++++ kernel/nsproxy.c | 2 +- kernel/pid.c | 4 ++-- 5 files changed, 11 insertions(+), 5 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 0b09447ae040..6ffb769ed955 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -776,7 +776,7 @@ static int de_thread(struct task_struct *tsk) * so it is safe to do it under read_lock. */ if (unlikely(tsk->group_leader == child_reaper(tsk))) - tsk->nsproxy->pid_ns->child_reaper = tsk; + task_active_pid_ns(tsk)->child_reaper = tsk; zap_other_threads(tsk); read_unlock(&tasklist_lock); diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c index d6dc72c78bc1..e0d064e9764e 100644 --- a/fs/proc/proc_misc.c +++ b/fs/proc/proc_misc.c @@ -91,7 +91,8 @@ static int loadavg_read_proc(char *page, char **start, off_t off, LOAD_INT(a), LOAD_FRAC(a), LOAD_INT(b), LOAD_FRAC(b), LOAD_INT(c), LOAD_FRAC(c), - nr_running(), nr_threads, current->nsproxy->pid_ns->last_pid); + nr_running(), nr_threads, + task_active_pid_ns(current)->last_pid); return proc_calc_metrics(page, start, off, count, eof, len); } diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h index c471c0c6e9ce..d10cb5f75c06 100644 --- a/include/linux/pid_namespace.h +++ b/include/linux/pid_namespace.h @@ -39,6 +39,11 @@ static inline void put_pid_ns(struct pid_namespace *ns) kref_put(&ns->kref, free_pid_ns); } +static inline struct pid_namespace *task_active_pid_ns(struct task_struct *tsk) +{ + return tsk->nsproxy->pid_ns; +} + static inline struct task_struct *child_reaper(struct task_struct *tsk) { return init_pid_ns.child_reaper; diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c index ac99837e7a04..e981c61304f1 100644 --- a/kernel/nsproxy.c +++ b/kernel/nsproxy.c @@ -87,7 +87,7 @@ static struct nsproxy *create_new_namespaces(unsigned long flags, goto out_ipc; } - new_nsp->pid_ns = copy_pid_ns(flags, tsk->nsproxy->pid_ns); + new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk)); if (IS_ERR(new_nsp->pid_ns)) { err = PTR_ERR(new_nsp->pid_ns); goto out_pid; diff --git a/kernel/pid.c b/kernel/pid.c index 42de9af8c524..78c0dbffde65 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -214,7 +214,7 @@ struct pid *alloc_pid(void) int nr = -1; struct pid_namespace *ns; - ns = current->nsproxy->pid_ns; + ns = task_active_pid_ns(current); pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL); if (!pid) goto out; @@ -364,7 +364,7 @@ struct pid *find_ge_pid(int nr) pid = find_pid(nr); if (pid) break; - nr = next_pidmap(current->nsproxy->pid_ns, nr); + nr = next_pidmap(task_active_pid_ns(current), nr); } while (nr > 0); return pid; -- 2.20.1