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Takashi Iwai 75334c9cd6 PCI: Restore original INTX_DISABLE bit by pcim_intx() 
[ Upstream commit 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+
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-02-27 04:30:15 -08:00
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README

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.