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hwmon: (powerz) Avoid cacheline sharing for DMA buffer

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Depending on the architecture the transfer buffer may share a cacheline
with the following mutex. As the buffer may be used for DMA, that is
problematic.

Use the high-level DMA helpers to make sure that cacheline sharing can
not happen.

Also drop the comment, as the helpers are documentation enough.

https://sashiko.dev/#/message/20260408175814.934BFC19421%40smtp.kernel.org

Fixes: 4381a36abd ("hwmon: add POWER-Z driver")
Cc: stable@vger.kernel.org # ca085faabb42: dma-mapping: add __dma_from_device_group_begin()/end()
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20260408-powerz-cacheline-alias-v1-1-1254891be0dd@weissschuh.net
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Thomas Weißschuh 2026-04-08 20:45:50 +02:00 committed by Guenter Roeck
parent a7c0aaa50e
commit 3023c050af
1 changed files with 4 additions and 1 deletions
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5
drivers/hwmon/powerz.c
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@ -6,6 +6,7 @@
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/hwmon.h>
#include <linux/module.h>
#include <linux/mutex.h>
@ -33,7 +34,9 @@ struct powerz_sensor_data {
} __packed;
struct powerz_priv {
char transfer_buffer[64]; /* first member to satisfy DMA alignment */
__dma_from_device_group_begin();
char transfer_buffer[64];
__dma_from_device_group_end();
struct mutex mutex;
struct completion completion;
struct urb *urb;