Re: [PATCH v5] staging: most: video: prevent probes during component exit

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Dec 03, 2025 at 03:34:11AM -0500, Pavan Kumar Yalagada wrote:
> When comp_exit() runs, comp_probe_channel() could still add new devices
> to video_devices, creating a race and potentially leaving the list in
> an inconsistent state.

Wait, please step back.  How can this happen?  I would argue that if it
could happen, then this must be solved at the higher level.  The most
core should not be allowing this, as you do not want to be forced to
solve this for each individual driver (hint, the driver core does not
allow this to happen for normal driver operations for this very reason.)

You are only solving this for one most driver, not all of them (well,
there are only two with this codepath...)  Please move back up the stack
a bit and prevent this from even being an issue at all.  Especially as I
do not think this really solves the problem, see below:

> This patch prevents new devices from being added while exiting by:
> 
> - comp_probe_channel() checks comp_exiting before modifying video_devices.
> 
> 	if (comp_exiting) {
> 		spin_unlock_irq(&list_lock);
> 		ret = -BUSY;
> 		goto err_unreg;
> 	}

That's great, but what prevents comp_exiting from changing right after
you check it?

thanks,

greg k-h