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d555ed45a5
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: 25216afc9d ("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+