Minor comment.
Oren Laadan [orenl@xxxxxxxxxxxxxxx] wrote:
| From 0fd2795c29fec51eec75f76ea21394367b6801db Mon Sep 17 00:00:00 2001
| From: Oren Laadan <orenl@xxxxxxxxxxxxxxx>
| Date: Tue, 21 Oct 2008 16:26:10 -0400
| Subject: [PATCH 13/29] External checkpoint of a task other than ourself
|
| Now we can do "external" checkpoint, i.e. act on another task.
|
| sys_checkpoint() now looks up the target pid (in our namespace) and
| checkpoints that corresponding task. That task should be the root of
| a container.
|
| sys_restart() remains the same, as the restart is always done in the
| context of the restarting task.
|
| Changelog[v14]:
| - Refuse non-self checkpoint if target task isn't frozen
|
| Changelog[v12]:
| - Replace obsolete cr_debug() with pr_debug()
|
| Changelog[v11]:
| - Copy contents of 'init->fs->root' instead of pointing to them
|
| Changelog[v10]:
| - Grab vfs root of container init, rather than current process
|
| Signed-off-by: Oren Laadan <orenl@xxxxxxxxxxxxxxx>
| Acked-by: Serge Hallyn <serue@xxxxxxxxxx>
| ---
| checkpoint/checkpoint.c | 73 ++++++++++++++++++++++++++++++++++++++++++-
| checkpoint/restart.c | 4 +-
| checkpoint/sys.c | 6 +++
| include/linux/checkpoint.h | 2 +
| 4 files changed, 81 insertions(+), 4 deletions(-)
|
| diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
| index d4e0007..25229d3 100644
| --- a/checkpoint/checkpoint.c
| +++ b/checkpoint/checkpoint.c
| @@ -10,6 +10,8 @@
|
| #include <linux/version.h>
| #include <linux/sched.h>
| +#include <linux/freezer.h>
| +#include <linux/ptrace.h>
| #include <linux/time.h>
| #include <linux/fs.h>
| #include <linux/file.h>
| @@ -242,6 +244,11 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
| {
| int ret;
|
| + if (t->state == TASK_DEAD) {
| + pr_warning("c/r: task may not be in state TASK_DEAD\n");
| + return -EAGAIN;
| + }
| +
| ret = cr_write_task_struct(ctx, t);
| cr_debug("task_struct: ret %d\n", ret);
| if (ret < 0)
| @@ -264,22 +271,84 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
| return ret;
| }
|
| +static int cr_get_container(struct cr_ctx *ctx, pid_t pid)
| +{
| + struct task_struct *task = NULL;
| + struct nsproxy *nsproxy = NULL;
| + int err = -ESRCH;
| +
| + ctx->root_pid = pid;
| +
| + read_lock(&tasklist_lock);
| + task = find_task_by_vpid(pid);
| + if (task)
| + get_task_struct(task);
| + read_unlock(&tasklist_lock);
| +
| + if (!task)
| + goto out;
| +
| +#if 0 /* enable to use containers */
| + if (!is_container_init(task)) {
| + err = -EINVAL;
| + goto out;
| + }
| +#endif
| +
| + if (!ptrace_may_access(task, PTRACE_MODE_READ)) {
| + err = -EPERM;
| + goto out;
| + }
| +
| + /* verify that the task is frozen (unless self) */
| + if (task != current && !frozen(task))
| + return -EBUSY;
| +
| + rcu_read_lock();
| + if (task_nsproxy(task)) {
| + nsproxy = task_nsproxy(task);
Nit: why call task_nproxy() twice ?
| + get_nsproxy(nsproxy);
| + }
| + rcu_read_unlock();
| +
| + if (!nsproxy)
| + goto out;
Sukadev
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