Re: [PATCH 03/11] kthread: Pass in the thread's name during creation

Mike Christie
2023-03-12T01:48:40Z

On 3/11/23 10:11 AM, michael.christie@oracle.com wrote:
> On 3/11/23 2:53 AM, Christian Brauner wrote:
>> On Fri, Mar 10, 2023 at 04:03:24PM -0600, Mike Christie wrote:
>>> This has us pass in the thread's name during creation in kernel_thread.
>>>
>>> Signed-off-by: Mike Christie <michael.christie@oracle.com>
>>> ---
>>> kernel/kthread.c | 35 ++++++++++++++---------------------
>>> 1 file changed, 14 insertions(+), 21 deletions(-)
>>>
>>> diff --git a/kernel/kthread.c b/kernel/kthread.c
>>> index 63574cee925e..831a55b406d8 100644
>>> --- a/kernel/kthread.c
>>> +++ b/kernel/kthread.c
>>> @@ -38,6 +38,7 @@ struct task_struct *kthreadd_task;
>>> struct kthread_create_info
>>> {
>>> /* Information passed to kthread() from kthreadd. */
>>> + char *full_name;
>>> int (*threadfn)(void *data);
>>> void *data;
>>> int node;
>>> @@ -343,10 +344,15 @@ static int kthread(void *_create)
>>> /* Release the structure when caller killed by a fatal signal. */
>>> done = xchg(&create->done, NULL);
>>> if (!done) {
>>> + kfree(create->full_name);
>>> kfree(create);
>>> kthread_exit(-EINTR);
>>> }
>>>
>>> + if (strlen(create->full_name) >= TASK_COMM_LEN)
>>> + self->full_name = create->full_name;
>>> + else
>>> + kfree(create->full_name);
>>
>> This is monir but wwiw, this looks suspicious when reading it without
>> more context. It took me a while to see that kthread->full_name is
>> intended to store the untruncated name only if truncation actually needs
>> to happen. So either we should always initialize this or we should add a
>> comment. You can just send a tiny patch that I can fold into this one so
>> you don't have to resend the whole series...

Hey Christian, here is a patch you can fold into the original. Thanks
for your help.

From ac82986ec4e7faae245ec48cb9213a4ca1c1d4d6 Mon Sep 17 00:00:00 2001
From: Mike Christie <michael.christie@oracle.com>
Date: Sat, 11 Mar 2023 16:14:24 -0600
Subject: [PATCH] kthread: Always save the full_name

Simplify the kthread name handling by always using the full_name.
---
kernel/kthread.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 831a55b406d8..5596ec3f75cf 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -349,10 +349,7 @@ static int kthread(void *_create)
kthread_exit(-EINTR);
}

- if (strlen(create->full_name) >= TASK_COMM_LEN)
- self->full_name = create->full_name;
- else
- kfree(create->full_name);
+ self->full_name = create->full_name;
self->threadfn = threadfn;
self->data = data;