Applied "spi: document odd controller reference handling" to the spi tree

Commit Message

Mark Brown Oct. 31, 2017, 11:22 a.m. UTC

The patch

   spi: document odd controller reference handling

has been applied to the spi tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

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Thanks,
Mark

From 68b892f1fdc493d7cd4e4067596879cd097c1f62 Mon Sep 17 00:00:00 2001
From: Johan Hovold <[e-mail]>
Date: Mon, 30 Oct 2017 11:35:26 +0100
Subject: [PATCH] spi: document odd controller reference handling

Document the fact that a reference to the controller is dropped as part
of deregistration.

This is an odd pattern as the reference is typically taken in
__spi_alloc_controller() rather than spi_register_controller(). Most
controller drivers gets it right these days and notably the
device-managed interface relies on this behaviour.

Signed-off-by: Johan Hovold <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>
---
 drivers/spi/spi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Patch

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 6e65524cbfd9..5673cca1d1d0 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2195,7 +2195,7 @@  static void devm_spi_unregister(struct device *dev, void *res)
  * Context: can sleep
  *
  * Register a SPI device as with spi_register_controller() which will
- * automatically be unregister
+ * automatically be unregistered and freed.
  *
  * Return: zero on success, else a negative error code.
  */
@@ -2236,6 +2236,8 @@  static int __unregister(struct device *dev, void *null)
  * only ones directly touching chip registers.
  *
  * This must be called from context that can sleep.
+ *
+ * Note that this function also drops a reference to the controller.
  */
 void spi_unregister_controller(struct spi_controller *ctlr)
 {