From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
Date: Fri, 13 Mar 2009 17:25:42 -0700
Subject: [PATCH 5/6] Define and use proc_pid_checkpointable()
Create a proc file, /proc/pid/checkpointable, which shows '1' if
task is checkpointable and '0' if it is not.
To determine whether a task is checkpointable, the handler for this
new proc file, shares the same code with sys_checkpoint().
Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
---
checkpoint/checkpoint.c | 23 ++++++++++++++++-------
fs/proc/base.c | 13 +++++++++++++
include/linux/checkpoint.h | 7 +++++++
3 files changed, 36 insertions(+), 7 deletions(-)
diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
index c16f30c..ad0956c 100644
--- a/checkpoint/checkpoint.c
+++ b/checkpoint/checkpoint.c
@@ -264,22 +264,31 @@ static int cr_write_all_tasks(struct cr_ctx *ctx)
return ret;
}
+int task_checkpointable(struct task_struct *t)
+{
+ if (t->state == TASK_DEAD) {
+ pr_warning("c/r: task %d is TASK_DEAD\n", task_pid_vnr(t));
+ return 0;
+ }
+
+ /* Verify that task is frozen, unless it is self-checkpoint */
+ if (t != current && !frozen(t))
+ return 0;
+
+ return 1;
+}
+
static int cr_may_checkpoint_task(struct task_struct *t, struct cr_ctx *ctx)
{
pr_debug("check %d\n", task_pid_nr_ns(t, ctx->root_nsproxy->pid_ns));
- if (t->state == TASK_DEAD) {
- pr_warning("c/r: task %d is TASK_DEAD\n", task_pid_vnr(t));
+ /* verify that the task is checkpointable */
+ if (!task_checkpointable(t))
return -EAGAIN;
- }
if (!ptrace_may_access(t, PTRACE_MODE_READ))
return -EPERM;
- /* verify that the task is frozen (unless self) */
- if (t != current && !frozen(t))
- return -EBUSY;
-
/* FIXME: change this for nested containers */
if (task_nsproxy(t) != ctx->root_nsproxy)
return -EPERM;
diff --git a/fs/proc/base.c b/fs/proc/base.c
index bde92c3..989ca93 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2501,6 +2501,13 @@ static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
return 0;
}
+#ifdef CONFIG_CHECKPOINT_RESTART
+static int proc_pid_checkpointable(struct task_struct *task, char *buffer)
+{
+ return sprintf(buffer, "%d\n", task_checkpointable(task));
+}
+#endif
+
/*
* Thread groups
*/
@@ -2580,6 +2587,9 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_TASK_IO_ACCOUNTING
INF("io", S_IRUGO, proc_tgid_io_accounting),
#endif
+#ifdef CONFIG_CHECKPOINT_RESTART
+ INF("checkpointable", S_IRUGO, proc_pid_checkpointable),
+#endif
};
static int proc_tgid_base_readdir(struct file * filp,
@@ -2915,6 +2925,9 @@ static const struct pid_entry tid_base_stuff[] = {
#ifdef CONFIG_TASK_IO_ACCOUNTING
INF("io", S_IRUGO, proc_tid_io_accounting),
#endif
+#ifdef CONFIG_CHECKPOINT_RESTART
+ INF("checkpointable", S_IRUGO, proc_pid_checkpointable),
+#endif
};
static int proc_tid_base_readdir(struct file * filp,
diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
index 484be56..d1f53a6 100644
--- a/include/linux/checkpoint.h
+++ b/include/linux/checkpoint.h
@@ -142,6 +142,8 @@ static inline int cr_enabled(void)
return 1;
}
+int task_checkpointable(struct task_struct *t);
+
#else /* !CONFIG_CHECKPOINT_RESTART */
static inline void files_deny_checkpointing(struct files_struct *files) {}
@@ -162,5 +164,10 @@ static inline int cr_enabled(void)
return 0;
}
+static inline int task_checkpointable(struct task_struct *t)
+{
+ return 0;
+}
+
#endif /* CONFIG_CHECKPOINT_RESTART */
#endif /* _CHECKPOINT_CKPT_H_ */
--
1.5.2.5
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