linux-kernel - Re: [PATCH 5.10] tracing: Add tracing_reset_all_online_cpus

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Date:   Mon, 19 Jun 2023 21:38:06 +0800
From:   Zheng Yejian <zhengyejian1@...wei.com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     <rostedt@...dmis.org>, <mhiramat@...nel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-trace-kernel@...r.kernel.org>, <stable@...r.kernel.org>
Subject: Re: [PATCH 5.10] tracing: Add
 tracing_reset_all_online_cpus_unlocked() function

On 2023/6/19 16:26, Greg KH wrote:
> On Fri, Jun 16, 2023 at 04:49:31AM +0800, Zheng Yejian wrote:
>> From: "Steven Rostedt (Google)" <rostedt@...dmis.org>
>>
>> commit e18eb8783ec4949adebc7d7b0fdb65f65bfeefd9 upstream.
>>
>> Currently the tracing_reset_all_online_cpus() requires the
>> trace_types_lock held. But only one caller of this function actually has
>> that lock held before calling it, and the other just takes the lock so
>> that it can call it. More users of this function is needed where the lock
>> is not held.
>>
>> Add a tracing_reset_all_online_cpus_unlocked() function for the one use
>> case that calls it without being held, and also add a lockdep_assert to
>> make sure it is held when called.
>>
>> Then have tracing_reset_all_online_cpus() take the lock internally, such
>> that callers do not need to worry about taking it.
>>
>> Link: https://lkml.kernel.org/r/20221123192741.658273220@goodmis.org
>>
>> Cc: Masami Hiramatsu <mhiramat@...nel.org>
>> Cc: Andrew Morton <akpm@...ux-foundation.org>
>> Cc: Zheng Yejian <zhengyejian1@...wei.com>
>> Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
>> [this patch is pre-depended by be111ebd8868d4b7c041cb3c6102e1ae27d6dc1d
>> due to tracing_reset_all_online_cpus() should be called after taking lock]
>> Fixes: be111ebd8868 ("tracing: Free buffers when a used dynamic event is removed")
>> Signed-off-by: Zheng Yejian <zhengyejian1@...wei.com>
>> ---
> 
> 
> What about for 5.15.y?  You can't apply a fix to just an older tree as
> you will then have a regression when you update.
> 
> I'll drop this one from my queue, please resend a backport for all
> relevent stable releases.

Hi, greg,

I have resend the patch to relevent stable releases:
5.15.y: 
https://lore.kernel.org/all/20230620013052.1127047-1-zhengyejian1@huawei.com/
5.10.y: 
https://lore.kernel.org/all/20230620013104.1127100-1-zhengyejian1@huawei.com/
5.4.y: 
https://lore.kernel.org/all/20230620013113.1127152-1-zhengyejian1@huawei.com/

---

Thanks,
Zheng Yejian

> 
> thanks,
> 
> greg k-h