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driver core: Replace dev->dma_skip_sync with dev_dma_skip_sync()

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In C, bitfields are not necessarily safe to modify from multiple
threads without locking. Switch "dma_skip_sync" over to the "flags"
field so modifications are safe.

Cc: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patch.msgid.link/20260406162231.v5.4.Icf072aa4184dd86a88fa8ca195b09d1651984000@changeid
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
This commit is contained in:
Douglas Anderson 2026-04-06 16:22:57 -07:00 committed by Danilo Krummrich
parent 7fa1e85cfe
commit d99167df04
5 changed files with 12 additions and 12 deletions
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8
include/linux/device.h
View File

@ -517,12 +517,15 @@ struct device_physical_location {
* until other devices probe successfully.
* @DEV_FLAG_DMA_IOMMU: Device is using default IOMMU implementation for DMA and
* doesn't rely on dma_ops structure.
* @DEV_FLAG_DMA_SKIP_SYNC: DMA sync operations can be skipped for coherent
* buffers.
* @DEV_FLAG_COUNT: Number of defined struct_device_flags.
*/
enum struct_device_flags {
DEV_FLAG_READY_TO_PROBE = 0,
DEV_FLAG_CAN_MATCH = 1,
DEV_FLAG_DMA_IOMMU = 2,
DEV_FLAG_DMA_SKIP_SYNC = 3,
DEV_FLAG_COUNT
};
@ -616,7 +619,6 @@ enum struct_device_flags {
* and optionall (if the coherent mask is large enough) also
* for dma allocations. This flag is managed by the dma ops
* instance from ->dma_supported.
* @dma_skip_sync: DMA sync operations can be skipped for coherent buffers.
* @flags: DEV_FLAG_XXX flags. Use atomic bitfield operations to modify.
*
* At the lowest level, every device in a Linux system is represented by an
@ -733,9 +735,6 @@ struct device {
#ifdef CONFIG_DMA_OPS_BYPASS
bool dma_ops_bypass : 1;
#endif
#ifdef CONFIG_DMA_NEED_SYNC
bool dma_skip_sync:1;
#endif
DECLARE_BITMAP(flags, DEV_FLAG_COUNT);
};
@ -765,6 +764,7 @@ static inline bool dev_test_and_set_##accessor_name(struct device *dev) \
__create_dev_flag_accessors(ready_to_probe, DEV_FLAG_READY_TO_PROBE);
__create_dev_flag_accessors(can_match, DEV_FLAG_CAN_MATCH);
__create_dev_flag_accessors(dma_iommu, DEV_FLAG_DMA_IOMMU);
__create_dev_flag_accessors(dma_skip_sync, DEV_FLAG_DMA_SKIP_SYNC);
#undef __create_dev_flag_accessors

4
include/linux/dma-map-ops.h
View File

@ -240,8 +240,8 @@ static inline void dma_reset_need_sync(struct device *dev)
{
#ifdef CONFIG_DMA_NEED_SYNC
/* Reset it only once so that the function can be called on hotpath */
if (unlikely(dev->dma_skip_sync))
dev->dma_skip_sync = false;
if (unlikely(dev_dma_skip_sync(dev)))
dev_clear_dma_skip_sync(dev);
#endif
}

2
include/linux/dma-mapping.h
View File

@ -429,7 +429,7 @@ bool __dma_need_sync(struct device *dev, dma_addr_t dma_addr);
static inline bool dma_dev_need_sync(const struct device *dev)
{
/* Always call DMA sync operations when debugging is enabled */
return !dev->dma_skip_sync || IS_ENABLED(CONFIG_DMA_API_DEBUG);
return !dev_dma_skip_sync(dev) || IS_ENABLED(CONFIG_DMA_API_DEBUG);
}
static inline void dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr,

8
kernel/dma/mapping.c
View File

@ -476,7 +476,7 @@ bool dma_need_unmap(struct device *dev)
{
if (!dma_map_direct(dev, get_dma_ops(dev)))
return true;
if (!dev->dma_skip_sync)
if (!dev_dma_skip_sync(dev))
return true;
return IS_ENABLED(CONFIG_DMA_API_DEBUG);
}
@ -492,16 +492,16 @@ static void dma_setup_need_sync(struct device *dev)
* mapping, if any. During the device initialization, it's
* enough to check only for the DMA coherence.
*/
dev->dma_skip_sync = dev_is_dma_coherent(dev);
dev_assign_dma_skip_sync(dev, dev_is_dma_coherent(dev));
else if (!ops->sync_single_for_device && !ops->sync_single_for_cpu &&
!ops->sync_sg_for_device && !ops->sync_sg_for_cpu)
/*
* Synchronization is not possible when none of DMA sync ops
* is set.
*/
dev->dma_skip_sync = true;
dev_set_dma_skip_sync(dev);
else
dev->dma_skip_sync = false;
dev_clear_dma_skip_sync(dev);
}
#else /* !CONFIG_DMA_NEED_SYNC */
static inline void dma_setup_need_sync(struct device *dev) { }

2
mm/hmm.c
View File

@ -709,7 +709,7 @@ int hmm_dma_map_alloc(struct device *dev, struct hmm_dma_map *map,
* best approximation to ensure no swiotlb buffering happens.
*/
#ifdef CONFIG_DMA_NEED_SYNC
dma_need_sync = !dev->dma_skip_sync;
dma_need_sync = !dev_dma_skip_sync(dev);
#endif /* CONFIG_DMA_NEED_SYNC */
if (dma_need_sync || dma_addressing_limited(dev))
return -EOPNOTSUPP;