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counter: fix privdata alignment

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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@kernel.org/

Fixes: c18e276030 ("counter: Provide alternative counter registration functions")
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240209-counter-align-fix-v2-1-5777ea0a2722@analog.com
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
This commit is contained in:
Nuno Sa 2024-02-09 16:50:34 +01:00 committed by William Breathitt Gray
parent 6613476e22
commit c83ccdc958
1 changed files with 4 additions and 3 deletions
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7
drivers/counter/counter-core.c
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@ -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)