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swiotlb: Make SWIOTLB_NO_FORCE perform no allocation

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When SWIOTLB_NO_FORCE is used, there should really be no allocations of
default_nslabs to occur since we are not going to use those slabs. If a
platform was somehow setting swiotlb_no_force and a later call to
swiotlb_init() was to be made we would still be proceeding with
allocating the default SWIOTLB size (64MB), whereas if swiotlb=noforce
was set on the kernel command line we would have only allocated 2KB.

This would be inconsistent and the point of initializing default_nslabs
to 1, was intended to allocate the minimum amount of memory possible, so
simply remove that minimal allocation period.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Florian Fainelli 2021-03-22 18:53:49 -07:00 committed by Konrad Rzeszutek Wilk
parent fcf044891c
commit 2726bf3ff2
1 changed files with 14 additions and 4 deletions
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18
kernel/dma/swiotlb.c
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@ -83,12 +83,10 @@ setup_io_tlb_npages(char *str)
} }
if (*str == ',') if (*str == ',')
++str; ++str;
if (!strcmp(str, "force")) { if (!strcmp(str, "force"))
swiotlb_force = SWIOTLB_FORCE; swiotlb_force = SWIOTLB_FORCE;
} else if (!strcmp(str, "noforce")) { else if (!strcmp(str, "noforce"))
swiotlb_force = SWIOTLB_NO_FORCE; swiotlb_force = SWIOTLB_NO_FORCE;
default_nslabs = 1;
}
return 0; return 0;
} }
@ -174,6 +172,9 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
struct io_tlb_mem *mem; struct io_tlb_mem *mem;
size_t alloc_size; size_t alloc_size;
if (swiotlb_force == SWIOTLB_NO_FORCE)
return 0;
/* protect against double initialization */ /* protect against double initialization */
if (WARN_ON_ONCE(io_tlb_default_mem)) if (WARN_ON_ONCE(io_tlb_default_mem))
return -ENOMEM; return -ENOMEM;
@ -211,6 +212,9 @@ swiotlb_init(int verbose)
size_t bytes = PAGE_ALIGN(default_nslabs << IO_TLB_SHIFT); size_t bytes = PAGE_ALIGN(default_nslabs << IO_TLB_SHIFT);
void *tlb; void *tlb;
if (swiotlb_force == SWIOTLB_NO_FORCE)
return;
/* Get IO TLB memory from the low pages */ /* Get IO TLB memory from the low pages */
tlb = memblock_alloc_low(bytes, PAGE_SIZE); tlb = memblock_alloc_low(bytes, PAGE_SIZE);
if (!tlb) if (!tlb)
@ -240,6 +244,9 @@ swiotlb_late_init_with_default_size(size_t default_size)
unsigned int order; unsigned int order;
int rc = 0; int rc = 0;
if (swiotlb_force == SWIOTLB_NO_FORCE)
return 0;
/* /*
* Get IO TLB memory from the low pages * Get IO TLB memory from the low pages
*/ */
@ -276,6 +283,9 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
unsigned long bytes = nslabs << IO_TLB_SHIFT, i; unsigned long bytes = nslabs << IO_TLB_SHIFT, i;
struct io_tlb_mem *mem; struct io_tlb_mem *mem;
if (swiotlb_force == SWIOTLB_NO_FORCE)
return 0;
/* protect against double initialization */ /* protect against double initialization */
if (WARN_ON_ONCE(io_tlb_default_mem)) if (WARN_ON_ONCE(io_tlb_default_mem))
return -ENOMEM; return -ENOMEM;