Re: Can a driver->probe be called for two devices at the same time (WAS: Re: [PATCH] crypto/ccp: don't disable interrupts while setting up debugfs)

From: Gary R Hook
Date: Tue Feb 27 2018 - 15:11:38 EST


On 02/27/2018 01:36 PM, Sebastian Andrzej Siewior wrote:
On 2018-02-27 19:40:34 [+0100], Greg Kroah-Hartman wrote:
On Tue, Feb 27, 2018 at 06:33:14PM +0100, Sebastian Andrzej Siewior wrote:
On 2018-02-27 11:08:56 [-0600], Gary R Hook wrote:
That issue remains unclear to me: Are probes of PCI devices guaranteed to be
serialized? Observations on my CCPs says that they occur in order, but I
don't know for certain that serialization is guaranteed.

Is there a definitive statement on this somewhere that I just don't know
about?

The bus enforces this.

So the question if a driver can probe two devices simultaneously.

Depends on the bus type.

PCI

So the question is whether or not PCI enforces serial activity within a domain. The CCPs are all on different buses, so that doesn't matter.

I think we don't care in this situation, given that the CCP driver has minor requirements for locking. I just found it an interesting (albeit somewhat academic) question.

Thanks,
Gary