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Message-ID: <af67425d-8127-42d7-b874-099fa27f02a7@proxmox.com>
Date:   Wed, 13 Dec 2023 10:47:34 +0100
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Subject: Re: [RFC 2/2] PCI: acpiphp: slowdown hotplug if hotplugging multiple
 devices at a time
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To:     Igor Mammedov <imammedo@redhat.com>, linux-kernel@vger.kernel.org
Cc:     Dongli Zhang <dongli.zhang@oracle.com>, linux-acpi@vger.kernel.org,
        linux-pci@vger.kernel.org, mst@redhat.com, rafael@kernel.org,
        lenb@kernel.org, bhelgaas@google.com,
        mika.westerberg@linux.intel.com, boris.ostrovsky@oracle.com,
        joe.jin@oracle.com, stable@vger.kernel.org,
        Thomas Lamprecht <t.lamprecht@proxmox.com>
References: <20231213003614.1648343-1-imammedo@redhat.com>
 <20231213003614.1648343-3-imammedo@redhat.com>
From:   Fiona Ebner <f.ebner@proxmox.com>
In-Reply-To: <20231213003614.1648343-3-imammedo@redhat.com>
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Am 13.12.23 um 01:36 schrieb Igor Mammedov:
> previous commit ("PCI: acpiphp: enable slot only if it hasn't been enabled already"
> introduced a workaround to avoid a race between SCSI_SCAN_ASYNC job and
> bridge reconfiguration in case of single HBA hotplug.
> However in virt environment it's possible to pause machine hotplug several
> HBAs and let machine run. That can hit the same race when 2nd hotplugged
> HBA will start re-configuring bridge.
> Do the same thing as SHPC and throttle down hotplug of 2nd and up
> devices within single hotplug event.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>

With only the first patch applied, I could reproduce the issue described
here, i.e. pausing the vCPUs while doing multiple hotplugs and this
patch makes that scenario work too:

Tested-by: Fiona Ebner <f.ebner@proxmox.com>