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

Greg Kroah-Hartman
2021-12-15T17:46:39Z

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@ti.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> V4: New patch

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>