Patch "spi: Fix documentation of spi_alloc_master()" has been added to the 4.2-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    spi: Fix documentation of spi_alloc_master()

to the 4.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     spi-fix-documentation-of-spi_alloc_master.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From a394d635193b641f2c86ead5ada5b115d57c51f8 Mon Sep 17 00:00:00 2001
From: Guenter Roeck <linux@roeck-us.net>
Date: Sun, 6 Sep 2015 01:46:54 +0300
Subject: spi: Fix documentation of spi_alloc_master()

From: Guenter Roeck <linux@roeck-us.net>

commit a394d635193b641f2c86ead5ada5b115d57c51f8 upstream.

Actually, spi_master_put() after spi_alloc_master() must _not_ be followed
by kfree(). The memory is already freed with the call to spi_master_put()
through spi_master_class, which registers a release function. Calling both
spi_master_put() and kfree() results in often nasty (and delayed) crashes
elsewhere in the kernel, often in the networking stack.

This reverts commit eb4af0f5349235df2e4a5057a72fc8962d00308a.

Link to patch and concerns: https://lkml.org/lkml/2012/9/3/269
or
http://lkml.iu.edu/hypermail/linux/kernel/1209.0/00790.html

Alexey Klimov: This revert becomes valid after
94c69f765f1b4a658d96905ec59928e3e3e07e6a when spi-imx.c
has been fixed and there is no need to call kfree() so comment
for spi_alloc_master() should be fixed.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/spi/spi.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1437,8 +1437,7 @@ static struct class spi_master_class = {
  *
  * The caller is responsible for assigning the bus number and initializing
  * the master's methods before calling spi_register_master(); and (after errors
- * adding the device) calling spi_master_put() and kfree() to prevent a memory
- * leak.
+ * adding the device) calling spi_master_put() to prevent a memory leak.
  */
 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
 {


Patches currently in stable-queue which might be from linux@roeck-us.net are

queue-4.2/spi-fix-documentation-of-spi_alloc_master.patch
queue-4.2/lib-iommu-common.c-do-not-try-to-deref-a-null-iommu-lazy_flush-pointer-when-n-pool-hint.patch
queue-4.2/hwmon-nct6775-swap-step_up_time-and-step_down_time-registers-for-most-chips.patch
queue-4.2/watchdog-sunxi-fix-activation-of-system-reset.patch
queue-4.2/watchdog-imgpdc-unregister-restart-handler-on-remove.patch