Re: FAILED: patch "[PATCH] spi: bcm2835: Fix controller unregister order" failed to apply to 4.19-stable tree

[Sasha Levin <sashal@kernel.org>]

On Mon, Jun 15, 2020 at 05:22:00PM +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 9dd277ff92d06f6aa95b39936ad83981d781f49b Mon Sep 17 00:00:00 2001
>From: Lukas Wunner <lukas@wunner.de>
>Date: Fri, 15 May 2020 17:58:02 +0200
>Subject: [PATCH] spi: bcm2835: Fix controller unregister order
>
>The BCM2835 SPI driver uses devm_spi_register_controller() on bind.
>As a consequence, on unbind, __device_release_driver() first invokes
>bcm2835_spi_remove() before unregistering the SPI controller via
>devres_release_all().
>
>This order is incorrect:  bcm2835_spi_remove() tears down the DMA
>channels and turns off the SPI controller, including its interrupts
>and clock.  The SPI controller is thus no longer usable.
>
>When the SPI controller is subsequently unregistered, it unbinds all
>its slave devices.  If their drivers need to access the SPI bus,
>e.g. to quiesce their interrupts, unbinding will fail.
>
>As a rule, devm_spi_register_controller() must not be used if the
>->remove() hook performs teardown steps which shall be performed
>after unbinding of slaves.
>
>Fix by using the non-devm variant spi_register_controller().  Note that
>the struct spi_controller as well as the driver-private data are not
>freed until after bcm2835_spi_remove() has finished, so accessing them
>is safe.
>
>Fixes: 247263dba208 ("spi: bcm2835: use devm_spi_register_master()")
>Signed-off-by: Lukas Wunner <lukas@wunner.de>
>Cc: stable@vger.kernel.org # v3.13+
>Link: https://lore.kernel.org/r/2397dd70cdbe95e0bc4da2b9fca0f31cb94e5aed.1589557526.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