PCI: Restore original INTX_DISABLE bit by pcim_intx()

JIRA: https://issues.redhat.com/browse/RHEL-83611
Upstream Status: d555ed45a5a10a813528c7685f432369d536ae3d

commit d555ed45a5a10a813528c7685f432369d536ae3d
Author: Takashi Iwai <tiwai@suse.de>
Date:   Thu Oct 31 14:42:56 2024 +0100

    PCI: Restore original INTX_DISABLE bit by pcim_intx()

    pcim_intx() tries to restore the INTx bit at removal via devres, but there
    is a chance that it restores a wrong value.

    Because the value to be restored is blindly assumed to be the negative of
    the enable argument, when a driver calls pcim_intx() unnecessarily for the
    already enabled state, it'll restore to the disabled state in turn.  That
    is, the function assumes the case like:

      // INTx == 1
      pcim_intx(pdev, 0); // old INTx value assumed to be 1 -> correct

    but it might be like the following, too:

      // INTx == 0
      pcim_intx(pdev, 0); // old INTx value assumed to be 1 -> wrong

    Also, when a driver calls pcim_intx() multiple times with different enable
    argument values, the last one will win no matter what value it is.  This
    can lead to inconsistency, e.g.

      // INTx == 1
      pcim_intx(pdev, 0); // OK
      ...
      pcim_intx(pdev, 1); // now old INTx wrongly assumed to be 0

    This patch addresses those inconsistencies by saving the original INTx
    state at the first pcim_intx() call.  For that, get_or_create_intx_devres()
    is folded into pcim_intx() caller side; it allows us to simply check the
    already allocated devres and record the original INTx along with the
    devres_alloc() call.

    Link: https://lore.kernel.org/r/20241031134300.10296-1-tiwai@suse.de
    Fixes: 25216afc ("PCI: Add managed pcim_intx()")
    Link: https://lore.kernel.org/87v7xk2ps5.wl-tiwai@suse.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Philipp Stanner <pstanner@redhat.com>
    Cc: stable@vger.kernel.org      # v6.11+

Signed-off-by: Myron Stowe <mstowe@redhat.com>