linux-kernel - 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)

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Message-ID: <6a32bb01-209b-cdf2-093c-fe749627c806@amd.com>
Date:   Tue, 27 Feb 2018 11:45:59 -0600
From:   Gary R Hook <gary.hook@....com>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     "Hook, Gary" <ghook@....com>, linux-crypto@...r.kernel.org,
        Tom Lendacky <thomas.lendacky@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Subject: 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)

On 02/27/2018 11:33 AM, 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?
> 
> So the question if a driver can probe two devices simultaneously. I'm
> not sure. We have PROBE_PREFER_ASYNCHRONOUS which defers the probe to
> worker. However I have no idea if two of those worker can run at the
> same time.
> 
>> I think a mutex would be just fine; I got this wrong, clearly. Let me work
>> up a patch using a mutex.
> 
> I've sent one. Why not just ack it and be done with it?
> 
>> Gary
> 
> Sebastian
> 

Sorry, too much chaos right now. Of course.