Re: [PATCH v3 06/13] peci: Add device detection

On Mon, 2021-11-15 at 19:49 +0100, Greg Kroah-Hartman wrote:

On Mon, Nov 15, 2021 at 07:25:45PM +0100, Iwona Winiarska wrote:

quoted

+void peci_device_destroy(struct peci_device *device)
+{
+       bool killed;
+
+       device_lock(&device->dev);
+       killed = kill_device(&device->dev);

Eeek, why call this?

quoted

+       device_unlock(&device->dev);
+
+       if (!killed)
+               return;

What happened if something changed after you unlocked it?

We either killed it, or the other caller killed it.

Why is kill_device() required at all?  That's a very rare function to
call, and one that only one "bus" calls today because it is very
special (i.e. crazy and broken...)

It's used to avoid double-delete in case of races between peci_controller
unregister and "manually" removing the device using sysfs (pointed out by Dan in
v2). We're calling peci_device_destroy() in both callsites.
Other way to solve it would be to just have a peci-specific lock, but
kill_device seemed to be well suited for the problem at hand.
Do you suggest to remove it and just go with the lock?

Thanks
-Iwona

thanks,

greg k-h

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