Re: [patch V4 09-01/35] PCI/MSI: Decouple MSI[-X] disable from pcim_release()

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

On Wed, Dec 15, 2021 at 06:16:44PM +0100, Thomas Gleixner wrote:
> The MSI core will introduce runtime allocation of MSI related data. This
> data will be devres managed and has to be set up before enabling
> PCI/MSI[-X]. This would introduce an ordering issue vs. pcim_release().
> 
> The setup order is:
> 
>    pcim_enable_device()
>       devres_alloc(pcim_release...);
>       ...
>       pci_irq_alloc()
>         msi_setup_device_data()
>            devres_alloc(msi_device_data_release, ...)
> 
> and once the device is released these release functions are invoked in the
> opposite order:
> 
>     msi_device_data_release()
>     ...
>     pcim_release()
>        pci_disable_msi[x]()
> 
> which is obviously wrong, because pci_disable_msi[x]() requires the MSI
> data to be available to tear down the MSI[-X] interrupts.
> 
> Remove the MSI[-X] teardown from pcim_release() and add an explicit action
> to be installed on the attempt of enabling PCI/MSI[-X].
> 
> This allows the MSI core data allocation to be ordered correctly in a
> subsequent step.
> 
> Reported-by: Nishanth Menon <nm@xxxxxx>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> ---
> V4: New patch


Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>