Linux-SPI Archive on lore.kernel.org
 help / color / Atom feed
From: Lukas Wunner <lukas@wunner.de>
To: Mark Brown <broonie@kernel.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Jarkko Nikula <jarkko.nikula@linux.intel.com>,
	linux-spi@vger.kernel.org, Tsuchiya Yuto <kitakar@gmail.com>,
	Daniel Mack <daniel@zonque.org>,
	Haojian Zhuang <haojian.zhuang@gmail.com>,
	Robert Jarzmik <robert.jarzmik@free.fr>
Subject: [PATCH 2/3] spi: pxa2xx: Fix controller unregister order
Date: Mon, 25 May 2020 14:25:02 +0200
Message-ID: <834c446b1cf3284d2660f1bee1ebe3e737cd02a9.1590408496.git.lukas@wunner.de> (raw)
In-Reply-To: <cover.1590408496.git.lukas@wunner.de>

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")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206403#c1
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v2.6.17+
Cc: Tsuchiya Yuto <kitakar@gmail.com>
---
 drivers/spi/spi-pxa2xx.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 20dcbd35611a..2ecf0d8cd9f7 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -1885,7 +1885,7 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 
 	/* Register with the SPI framework */
 	platform_set_drvdata(pdev, drv_data);
-	status = devm_spi_register_controller(&pdev->dev, controller);
+	status = spi_register_controller(controller);
 	if (status != 0) {
 		dev_err(&pdev->dev, "problem registering spi controller\n");
 		goto out_error_pm_runtime_enabled;
@@ -1917,6 +1917,8 @@ static int pxa2xx_spi_remove(struct platform_device *pdev)
 
 	pm_runtime_get_sync(&pdev->dev);
 
+	spi_unregister_controller(drv_data->controller);
+
 	/* Disable the SSP at the peripheral and SOC level */
 	pxa2xx_spi_write(drv_data, SSCR0, 0);
 	clk_disable_unprepare(ssp->clk);
-- 
2.25.0


  parent reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-25 12:25 [PATCH 0/3] Intel SPI unbind fixes Lukas Wunner
2020-05-25 12:25 ` [PATCH 1/3] spi: dw: Fix controller unregister order Lukas Wunner
2020-05-25 13:15   ` Andy Shevchenko
2020-05-25 12:25 ` Lukas Wunner [this message]
2020-05-25 13:21   ` [PATCH 2/3] spi: pxa2xx: " Andy Shevchenko
2020-05-26  7:39     ` Lukas Wunner
2020-05-26  8:22       ` Andy Shevchenko
2020-05-27 12:09         ` Tsuchiya Yuto
2020-05-27 12:27           ` Andy Shevchenko
2020-05-27 13:14             ` Tsuchiya Yuto
2020-05-28  7:02               ` Tsuchiya Yuto
2020-05-28  8:41                 ` Andy Shevchenko
2020-05-28  9:31                   ` Lukas Wunner
2020-05-29 13:54                     ` Tsuchiya Yuto
2020-05-25 12:25 ` [PATCH 3/3] spi: pxa2xx: Fix runtime PM ref imbalance on probe error Lukas Wunner
2020-05-25 13:12   ` Andy Shevchenko
2020-05-26  8:46     ` Jarkko Nikula
2020-05-25 13:23 ` [PATCH 0/3] Intel SPI unbind fixes Andy Shevchenko
2020-05-26 16:46 ` Mark Brown

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=834c446b1cf3284d2660f1bee1ebe3e737cd02a9.1590408496.git.lukas@wunner.de \
    --to=lukas@wunner.de \
    --cc=andriy.shevchenko@linux.intel.com \
    --cc=broonie@kernel.org \
    --cc=daniel@zonque.org \
    --cc=haojian.zhuang@gmail.com \
    --cc=jarkko.nikula@linux.intel.com \
    --cc=kitakar@gmail.com \
    --cc=linux-spi@vger.kernel.org \
    --cc=robert.jarzmik@free.fr \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-SPI Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-spi/0 linux-spi/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-spi linux-spi/ https://lore.kernel.org/linux-spi \
		linux-spi@vger.kernel.org
	public-inbox-index linux-spi

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-spi


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git