Messages in this thread | | | Date | Thu, 30 Jul 2020 11:56:10 +0200 | From | Lukas Wunner <> | Subject | Re: [PATCH 2/3] driver core: Use rwsem for kill_device() serialization |
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On Thu, Jul 30, 2020 at 08:53:26AM +0200, Greg Kroah-Hartman wrote: > On Wed, Jul 08, 2020 at 03:27:02PM +0200, Lukas Wunner wrote: > > kill_device() is currently serialized with driver probing by way of the > > device_lock(). We're about to serialize it with device_add() as well > > to prevent addition of children below a device which is going away. > > Why? Who does this? Shouldn't the bus that is trying to do this know > this is happening?
AFAICS, at least spi and i2c are affected.
I first thought that pci is affected as well but it seems the global pci_lock_rescan_remove() performs the required serialization.
I've yet to take a closer look at acpi and usb. Any bus which creates a device hierarchy with dynamic addition & removal needs to make sure no new children are added after removal of the parent has begun.
> So, why are you pushing this down into the driver core, can't this be > done in whatever crazy bus wants to do this, like is done here?
I guess it can. Let me try to perform the locking at the bus level then.
Thanks,
Lukas
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