Patch "mmc: sdio: fix alignment issue in struct sdio_func" has been added to the 3.18-stable tree

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

mmc: sdio: fix alignment issue in struct sdio_func

to the 3.18-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:
mmc-sdio-fix-alignment-issue-in-struct-sdio_func.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Heiner Kallweit <[email protected]>
Date: Wed, 29 Mar 2017 20:54:37 +0200
Subject: mmc: sdio: fix alignment issue in struct sdio_func

From: Heiner Kallweit <[email protected]>

[ Upstream commit 5ef1ecf060f28ecef313b5723f1fd39bf5a35f56 ]

Certain 64-bit systems (e.g. Amlogic Meson GX) require buffers to be used for DMA to be 8-byte-aligned. struct sdio_func has an embedded small DMA buffer not meeting this requirement.
When testing switching to descriptor chain mode in meson-gx driver SDIO is broken therefore. Fix this by allocating the small DMA buffer separately as kmalloc ensures that the returned memory area is properly aligned for every basic data type.

---
 drivers/mmc/core/sdio_bus.c   |   12 +++++++++++-
 include/linux/mmc/sdio_func.h |    2 +-
 2 files changed, 12 insertions(+), 2 deletions(-)

@@ -265,7 +265,7 @@ static void sdio_release_func(struct dev
 	sdio_free_func_cis(func);
 
 	kfree(func->info);
-
+	kfree(func->tmpbuf);
 	kfree(func);
 }
 

@@ -280,6 +280,16 @@ struct sdio_func *sdio_alloc_func(struct
 	if (!func)
 		return ERR_PTR(-ENOMEM);
 
+	/*
+	 * allocate buffer separately to make sure it's properly aligned for
+	 * DMA usage (incl. 64 bit DMA)
+	 */
+	func->tmpbuf = kmalloc(4, GFP_KERNEL);
+	if (!func->tmpbuf) {
+		kfree(func);
+		return ERR_PTR(-ENOMEM);
+	}
+
 	func->card = card;
 
 	device_initialize(&func->dev);

@@ -53,7 +53,7 @@ struct sdio_func {
 	unsigned int		state;		/* function state */
 #define SDIO_STATE_PRESENT	(1<<0)		/* present in sysfs */
 
-	u8			tmpbuf[4];	/* DMA:able scratch buffer */
+	u8			*tmpbuf;	/* DMA:able scratch buffer */
 
 	unsigned		num_info;	/* number of info strings */
 	const char		**info;		/* info strings */

Patches currently in stable-queue which might be from [email protected] are

queue-3.18/mmc-sdio-fix-alignment-issue-in-struct-sdio_func.patch