linux-kernel - Re: [PATCH v2 0/3] ipmi: Close the race between __scan_channels() and deliver

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Message-ID: <aN_vFKhMi0tDT2rK@mail.minyard.net>
Date: Fri, 3 Oct 2025 10:43:16 -0500
From: Corey Minyard <corey@...yard.net>
To: Jinhui Guo <guojinhui.liam@...edance.com>
Cc: openipmi-developer@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/3] ipmi: Close the race between __scan_channels()
 and deliver_response()

On Tue, Sep 30, 2025 at 03:42:36PM +0800, Jinhui Guo wrote:
> The command "ipmi -b -t" would occasionally fail:
>   #ipmitool -b 6 -t 0x2c raw 0x6 0x01
>   Unable to send command: Invalid argument
>   Unable to send RAW command (channel=0x6 netfn=0x6 lun=0x0 cmd=0x1)
> 
> The race window between __scan_channels() and deliver_response() causes
> the parameters of some channels to be set to 0.
> 
> Fix the race between __scan_channels() and deliver_response() with the
> following changes.
> 
> 1. Only assign intf->channel_list = intf->wchannels and set
>    intf->channels_ready = true in channel_handler() after all channels_ready
>    have been successfully scanned or after failing to send the IPMI
>    request.
> 2. channel_handler() sets intf->channels_ready to true but no one clears
>    it, preventing __scan_channels() from rescanning channels. When the BMC
>    firmware changes a rescan is required. Allow it by clearing the flag
>    before starting a new scan.
> 3. Channels remain static unless the BMC firmware changes. Skip channel
>    rescan when no BMC firmware update has occurred.
> 
> 
> v1: https://lore.kernel.org/all/20250929081602.1901-1-guojinhui.liam@bytedance.com/
> 
> Changelog in v1 -> v2 (suggested by corey):
>  - Split the fix into three independent patches, each addressing a
>    separate issue.
>  - Clear intf->channels_ready only when the BMC firmware changes.
> 
> Jinhui Guo (3):
>   ipmi: Fix the race between __scan_channels() and deliver_response()
>   ipmi: Fix __scan_channels() failing to rescan channels
>   ipmi: Skip channel scan if channels are already marked ready

I have these queued for 6.18.  I need to re-review them; that will
probably happen later in the cycle; I can't put them in until 6.17-rc1
releases.

Thanks,

-corey

> 
>  drivers/char/ipmi/ipmi_msghandler.c | 24 +++++++++++++++++-------
>  1 file changed, 17 insertions(+), 7 deletions(-)
> 
> -- 
> 2.20.1
>