lkml.org 
[lkml]   [2010]   [Jun]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] procfs: Do not release pid_ns->proc_mnt too early
Date
[ Resending, hopefully with all pieces ]

Detached tasks are not seen by zap_pid_ns_processes()->sys_wait4(), so
that release_task()->proc_flush_task() of container init can be called
before it is for some detached tasks in the namespace.

Pin proc_mnt's in copy_process(), so that proc_flush_task() becomes safe
whatever the ordering of tasks.

Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
---
fs/proc/base.c | 18 ++++++++++++++++++
include/linux/proc_fs.h | 4 ++++
kernel/fork.c | 1 +
3 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index acb7ef8..d6cdd91 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2663,6 +2663,23 @@ static const struct inode_operations proc_tgid_base_inode_operations = {
.setattr = proc_setattr,
};

+/*
+ * Pin all proc_mnt so that detached tasks can safely call proc_flush_task()
+ * after container init calls itself proc_flush_task().
+ */
+void proc_new_task(struct task_struct *task)
+{
+ struct pid *pid;
+ int i;
+
+ if (!task->pid)
+ return;
+
+ pid = task_pid(task);
+ for (i = 0; i <= pid->level; i++)
+ mntget(pid->numbers[i].ns->proc_mnt);
+}
+
static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid)
{
struct dentry *dentry, *leader, *dir;
@@ -2744,6 +2761,7 @@ void proc_flush_task(struct task_struct *task)
upid = &pid->numbers[i];
proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
tgid->numbers[i].nr);
+ mntput(upid->ns->proc_mnt);
}

upid = &pid->numbers[pid->level];
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 379eaed..f24faa1 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -104,6 +104,7 @@ struct vmcore {

extern void proc_root_init(void);

+void proc_new_task(struct task_struct *task);
void proc_flush_task(struct task_struct *task);

extern struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode,
@@ -184,6 +185,9 @@ extern void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm);
#define proc_net_fops_create(net, name, mode, fops) ({ (void)(mode), NULL; })
static inline void proc_net_remove(struct net *net, const char *name) {}

+static inline void proc_new_task(struct task_struct *task)
+{
+}
static inline void proc_flush_task(struct task_struct *task)
{
}
diff --git a/kernel/fork.c b/kernel/fork.c
index b6cce14..c6c2874 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1281,6 +1281,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
total_forks++;
spin_unlock(&current->sighand->siglock);
write_unlock_irq(&tasklist_lock);
+ proc_new_task(p);
proc_fork_connector(p);
cgroup_post_fork(p);
perf_event_fork(p);
--
1.5.6.5


\
 
 \ /
  Last update: 2010-06-16 18:35    [from the cache]
©2003-2011 Jasper Spaans