Message-ID: <a1cca367-52b6-a6b1-fb01-890cad39fd29@suse.com>
Date:   Tue, 21 Mar 2023 10:09:22 +0100
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Subject: Re: [PATCH v2 1/1] Guard pci_create_sysfs_dev_files with atomic value
To:     Oliver Neukum <oneukum@suse.com>,
        Alexander Stein <alexander.stein@ew.tq-group.com>,
        Bjorn Helgaas <bhelgaas@google.com>
Cc:     Korneliusz Osmenda <korneliuszo@gmail.com>,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20230316091540.494366-1-alexander.stein@ew.tq-group.com>
 <4888964.44csPzL39Z@steina-w> <90e97b96-2918-294a-0e71-33a42f28d8a8@suse.com>
 <3607385.usQuhbGJ8B@steina-w> <ced8713f-69de-e48a-37eb-4f844e651b6b@suse.com>
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From:   Oliver Neukum <oneukum@suse.com>
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Am Donnerstag, 16. März 2023, 15:01:25 CET schrieb Oliver Neukum:
> I'm not sure if I can follow you here. Can you elaborate?

There are far better reasons to leave the setup of a PCI bus as the firmware
has done it than to leave a USB as is.


> How is it necessary? How do these PCI devices get attaches to the pci_bus_type 
> bus without calling pci_bus_add_device?

AFAICT they don't. But somebody has to call it.


> Okay, so which dependency is provided by pci_sysfs_init, which are required by 
> drivers then?

It isn't. It is missing from the code. But it exists in reality. That is the point.
You have a race condition between two probes. We cannot have that.
Hence IMHO the dependency would be best expressed by waiting for pci_sysfs_init()
to finish in the init sequence before you add any PCI bridges or devices to the system.

	Regards
		Oliver