Re: [RFC v17][PATCH 22/60] c/r: external checkpoint of a taskother than ourself

From: Serge E. Hallyn
Date: Thu Jul 23 2009 - 11:23:53 EST


Quoting Oren Laadan (orenl@xxxxxxxxxxx):
> +/* setup checkpoint-specific parts of ctx */
> +static int init_checkpoint_ctx(struct ckpt_ctx *ctx, pid_t pid)
> +{
> + struct task_struct *task;
> + struct nsproxy *nsproxy;
> + int ret;
> +
> + /*
> + * No need for explicit cleanup here, because if an error
> + * occurs then ckpt_ctx_free() is eventually called.
> + */
> +
> + ctx->root_pid = pid;
> +
> + /* root task */
> + read_lock(&tasklist_lock);
> + task = find_task_by_vpid(pid);
> + if (task)
> + get_task_struct(task);
> + read_unlock(&tasklist_lock);
> + if (!task)
> + return -ESRCH;
> + else
> + ctx->root_task = task;
> +
> + /* root nsproxy */
> + rcu_read_lock();
> + nsproxy = task_nsproxy(task);
> + if (nsproxy)
> + get_nsproxy(nsproxy);
> + rcu_read_unlock();
> + if (!nsproxy)
> + return -ESRCH;
> + else
> + ctx->root_nsproxy = nsproxy;
> +
> + /* root freezer */
> + ctx->root_freezer = task;
> + geT_task_struct(task);
> +
> + ret = may_checkpoint_task(ctx, task);
> + if (ret) {
> + ckpt_write_err(ctx, NULL);
> + put_task_struct(task);
> + put_task_struct(task);
> + put_nsproxy(nsproxy);

I don't think this is safe - the ckpt_ctx_free() will
free them a second time because you're not setting them
to NULL, right?

> + return ret;
> + }
> +
> + return 0;
> +}
> +

-serge
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