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Merge tag 'dma-mapping-6.6-2023-09-30' of git://git.infradead.org/users/hch/dma-mapping

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Pull dma-mapping fixes from Christoph Hellwig:

 - fix the narea calculation in swiotlb initialization (Ross Lagerwall)

 - fix the check whether a device has used swiotlb (Petr Tesarik)

* tag 'dma-mapping-6.6-2023-09-30' of git://git.infradead.org/users/hch/dma-mapping:
  swiotlb: fix the check whether a device has used software IO TLB
  swiotlb: use the calculated number of areas
This commit is contained in:
Linus Torvalds
2023-09-30 11:07:26 -07:00
parent 25d48d570e 2d5780bbef
commit 3b517966c5
2 changed files with 38 additions and 16 deletions
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31
kernel/dma/swiotlb.c
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@@ -399,14 +399,13 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags,
}
mem->areas = memblock_alloc(array_size(sizeof(struct io_tlb_area),
default_nareas), SMP_CACHE_BYTES);
nareas), SMP_CACHE_BYTES);
if (!mem->areas) {
pr_warn("%s: Failed to allocate mem->areas.\n", __func__);
return;
}
swiotlb_init_io_tlb_pool(mem, __pa(tlb), nslabs, false,
default_nareas);
swiotlb_init_io_tlb_pool(mem, __pa(tlb), nslabs, false, nareas);
add_mem_pool(&io_tlb_default_mem, mem);
if (flags & SWIOTLB_VERBOSE)
@@ -729,9 +728,6 @@ static void swiotlb_dyn_alloc(struct work_struct *work)
}
add_mem_pool(mem, pool);
/* Pairs with smp_rmb() in is_swiotlb_buffer(). */
smp_wmb();
}
/**
@@ -1152,9 +1148,26 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
spin_unlock_irqrestore(&dev->dma_io_tlb_lock, flags);
found:
dev->dma_uses_io_tlb = true;
/* Pairs with smp_rmb() in is_swiotlb_buffer() */
smp_wmb();
WRITE_ONCE(dev->dma_uses_io_tlb, true);
/*
* The general barrier orders reads and writes against a presumed store
* of the SWIOTLB buffer address by a device driver (to a driver private
* data structure). It serves two purposes.
*
* First, the store to dev->dma_uses_io_tlb must be ordered before the
* presumed store. This guarantees that the returned buffer address
* cannot be passed to another CPU before updating dev->dma_uses_io_tlb.
*
* Second, the load from mem->pools must be ordered before the same
* presumed store. This guarantees that the returned buffer address
* cannot be observed by another CPU before an update of the RCU list
* that was made by swiotlb_dyn_alloc() on a third CPU (cf. multicopy
* atomicity).
*
* See also the comment in is_swiotlb_buffer().
*/
smp_mb();
*retpool = pool;
return index;