Serge E. Hallyn [serue@xxxxxxxxxx] wrote:
| > #ifdef CONFIG_CHECKPOINT_RESTART
| > +static char *explain_checkpointable(int reason)
| > +{
| > + char *message;
| > +
| > + switch(reason) {
| > + case CR_CHECKPOINTABLE: message = "1"; break;
| > + case CR_DEAD: message = "0 (dead)"; break;
| > + case CR_NOT_FROZEN: message = "0 (not frozen)"; break;
| > + default: message = "0 (unknown)"; break;
|
| I don't think splitting it up this way is going to work long-term.
| It means you need one code for each type of message, and can't give
| any more detail beyond that (i.e. the value of
| current->nsproxy->uts_ns.refcount, or whatever).
|
| I think it would be better to pass a buffer into __task_checkpointable,
| and let task_checkpointable() pass in a NULL buffer meaning "I
| (sys_checkpoint) don't care about the explanation".
Ok. I had tried it before, but was not happy about __task_checkpointable()
filling in a message buffer, but I see your point. Here is an updated patch.
---
>From 73dd3ec01320d62881cb5296aa4d68667571ef4c Mon Sep 17 00:00:00 2001
From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
Date: Tue, 17 Mar 2009 16:15:16 -0700
Subject: [PATCH 6/6] Explain reason for task being uncheckpointable
Try to give an useful message on why a task is uncheckpointable.
Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
---
checkpoint/checkpoint.c | 16 ++++++++++++++--
fs/proc/base.c | 4 +++-
include/linux/checkpoint.h | 1 +
3 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
index ad0956c..b4dbb22 100644
--- a/checkpoint/checkpoint.c
+++ b/checkpoint/checkpoint.c
@@ -264,19 +264,31 @@ static int cr_write_all_tasks(struct cr_ctx *ctx)
return ret;
}
-int task_checkpointable(struct task_struct *t)
+int __task_checkpointable(struct task_struct *t, char *msg_buf, int len)
{
if (t->state == TASK_DEAD) {
+ if (msg_buf)
+ scnprintf(msg_buf, len, "0 (task dead)\n");
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))
+ if (t != current && !frozen(t)) {
+ if (msg_buf)
+ scnprintf(msg_buf, len, "0 (task not frozen)\n");
return 0;
+ }
+
+ if (msg_buf)
+ scnprintf(msg_buf, len, "1\n");
return 1;
}
+int task_checkpointable(struct task_struct *t)
+{
+ return __task_checkpointable(t, NULL, 0);
+}
static int cr_may_checkpoint_task(struct task_struct *t, struct cr_ctx *ctx)
{
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 989ca93..2d054b7 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2504,7 +2504,9 @@ static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
#ifdef CONFIG_CHECKPOINT_RESTART
static int proc_pid_checkpointable(struct task_struct *task, char *buffer)
{
- return sprintf(buffer, "%d\n", task_checkpointable(task));
+ __task_checkpointable(task, buffer, PAGE_SIZE);
+
+ return strlen(buffer);
}
#endif
diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
index d1f53a6..44adb0b 100644
--- a/include/linux/checkpoint.h
+++ b/include/linux/checkpoint.h
@@ -142,6 +142,7 @@ static inline int cr_enabled(void)
return 1;
}
+int __task_checkpointable(struct task_struct *t, char *msg_buf, int len);
int task_checkpointable(struct task_struct *t);
#else /* !CONFIG_CHECKPOINT_RESTART */
--
1.5.2.5
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