linux-kernel - Re: [PATCH v2] ring-buffer: Prevent inconsistent operation on cpu_buffer->resize

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Date:   Sun, 9 Apr 2023 19:30:53 +0700
From:   Bagas Sanjaya <bagasdotme@...il.com>
To:     Tze-nan Wu <Tze-nan.Wu@...iatek.com>, rostedt@...dmis.org,
        mhiramat@...nel.org
Cc:     bobule.chang@...iatek.com, wsd_upstream@...iatek.com,
        stable@...r.kernel.org,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v2] ring-buffer: Prevent inconsistent operation on
 cpu_buffer->resize_disabled

On 4/9/23 09:46, Tze-nan Wu wrote:
> This issue can be reproduced by "echo 0 > trace" and hotplug cpu at the
> same time. After reproducing success, we can find out buffer_size_kb
> will not be functional anymore.
> 

Do you mean disabling tracing while hotplugging CPU? Or disabling both
tracing and hotplug CPU?

> This patch uses cpus_read_lock() to prevent cpu_online_mask being changed
> between two different "for_each_online_buffer_cpu".
> 

"Use cpu_read_lock() to prevent ..."

> Changes in v2:
>   Use cpus_read_lock() instead of copying cpu_online_mask at the entry of
>   function
> 

To resolve kernel test robot warnings ([1] and [2])? Or have they been fixed?

[1]: https://lore.kernel.org/stable/202304081615.eiaqpbV8-lkp@intel.com/
[2]: https://lore.kernel.org/stable/202304082051.Dp50upfS-lkp@intel.com/

Thanks.

-- 
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