Patch "counter: fix privdata alignment" has been added to the 6.7-stable tree

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

    counter: fix privdata alignment

to the 6.7-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:
     counter-fix-privdata-alignment.patch
and it can be found in the queue-6.7 subdirectory.

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



commit 547162028d5c57b8d052618d85b61cd77937ecb8
Author: Nuno Sa <nuno.sa@xxxxxxxxxx>
Date:   Fri Feb 9 16:50:34 2024 +0100

    counter: fix privdata alignment
    
    [ Upstream commit c83ccdc9586b3e9882da9e27507c046751999d59 ]
    
    Aligning to the L1 cache does not guarantee the same alignment as
    kmallocing an object [1]. Furthermore, in some platforms, that
    alignment is not sufficient for DMA safety (in case someone wants
    to have a DMA safe buffer in privdata) [2].
    
    Sometime ago, we had the same fixes in IIO.
    
    [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/base/devres.c#n35
    [2]: https://lore.kernel.org/linux-iio/20220508175712.647246-2-jic23@xxxxxxxxxx/
    
    Fixes: c18e2760308e ("counter: Provide alternative counter registration functions")
    Signed-off-by: Nuno Sa <nuno.sa@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240209-counter-align-fix-v2-1-5777ea0a2722@xxxxxxxxxx
    Signed-off-by: William Breathitt Gray <william.gray@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c
index 09c77afb33ca8..3f24481fc04a1 100644
--- a/drivers/counter/counter-core.c
+++ b/drivers/counter/counter-core.c
@@ -31,10 +31,11 @@ struct counter_device_allochelper {
 	struct counter_device counter;
 
 	/*
-	 * This is cache line aligned to ensure private data behaves like if it
-	 * were kmalloced separately.
+	 * This ensures private data behaves like if it were kmalloced
+	 * separately. Also ensures the minimum alignment for safe DMA
+	 * operations (which may or may not mean cache alignment).
 	 */
-	unsigned long privdata[] ____cacheline_aligned;
+	unsigned long privdata[] __aligned(ARCH_DMA_MINALIGN);
 };
 
 static void counter_device_release(struct device *dev)




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