Re: FAILED: patch "[PATCH] spi: pxa2xx: Fix controller unregister order" failed to apply to 4.19-stable tree

[Sasha Levin <sashal@kernel.org>]

On Mon, Jun 15, 2020 at 05:21:18PM +0200, gregkh@linuxfoundation.org wrote:
>
>The patch below does not apply to the 4.19-stable tree.
>If someone wants it applied there, or to any other stable or longterm
>tree, then please email the backport, including the original git commit
>id to <stable@vger.kernel.org>.
>
>thanks,
>
>greg k-h
>
>------------------ original commit in Linus's tree ------------------
>
>From 32e5b57232c0411e7dea96625c415510430ac079 Mon Sep 17 00:00:00 2001
>From: Lukas Wunner <lukas@wunner.de>
>Date: Mon, 25 May 2020 14:25:02 +0200
>Subject: [PATCH] spi: pxa2xx: Fix controller unregister order
>
>The PXA2xx SPI driver uses devm_spi_register_controller() on bind.
>As a consequence, on unbind, __device_release_driver() first invokes
>pxa2xx_spi_remove() before unregistering the SPI controller via
>devres_release_all().
>
>This order is incorrect:  pxa2xx_spi_remove() disables the chip,
>rendering the SPI bus inaccessible even though the SPI controller is
>still registered.  When the SPI controller is subsequently unregistered,
>it unbinds all its slave devices.  Because their drivers cannot access
>the SPI bus, e.g. to quiesce interrupts, the slave devices may be left
>in an improper state.
>
>As a rule, devm_spi_register_controller() must not be used if the
>->remove() hook performs teardown steps which shall be performed after
>unregistering the controller and specifically after unbinding of slaves.
>
>Fix by reverting to the non-devm variant of spi_register_controller().
>
>An alternative approach would be to use device-managed functions for all
>steps in pxa2xx_spi_remove(), e.g. by calling devm_add_action_or_reset()
>on probe.  However that approach would add more LoC to the driver and
>it wouldn't lend itself as well to backporting to stable.
>
>The improper use of devm_spi_register_controller() was introduced in 2013
>by commit a807fcd090d6 ("spi: pxa2xx: use devm_spi_register_master()"),
>but all earlier versions of the driver going back to 2006 were likewise
>broken because they invoked spi_unregister_master() at the end of
>pxa2xx_spi_remove(), rather than at the beginning.
>
>Fixes: e0c9905e87ac ("[PATCH] SPI: add PXA2xx SSP SPI Driver")
>Signed-off-by: Lukas Wunner <lukas@wunner.de>
>Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>Cc: stable@vger.kernel.org # v2.6.17+
>Cc: Tsuchiya Yuto <kitakar@gmail.com>
>Link: https://bugzilla.kernel.org/show_bug.cgi?id=206403#c1
>Link: https://lore.kernel.org/r/834c446b1cf3284d2660f1bee1ebe3e737cd02a9.1590408496.git.lukas@wunner.de
>Signed-off-by: Mark Brown <broonie@kernel.org>

more work around master -> controller rename. Queued for 4.19, 4.14,
4.9, and 4.4.

-- 
Thanks,
Sasha