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Date: Mon, 19 Jul 2021 13:30:52 +0100
From: Will Deacon <will@...nel.org>
To: iommu@...ts.linux-foundation.org
Cc: linux-kernel@...r.kernel.org, Will Deacon <will@...nel.org>,
Guenter Roeck <linux@...ck-us.net>,
Claire Chang <tientzu@...omium.org>,
Christoph Hellwig <hch@....de>,
Robin Murphy <robin.murphy@....com>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH 3/5] swiotlb: Remove io_tlb_default_mem indirection
The indirection from the global 'io_tlb_default_mem' pointer to the
static '_io_tlb_default_mem' structure is ugly and unnecessary.
Convert all users to reference the static structure directly, using the
'nslabs' field to determine whether swiotlb has been initialised.
Cc: Claire Chang <tientzu@...omium.org>
Cc: Christoph Hellwig <hch@....de>
Cc: Robin Murphy <robin.murphy@....com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Tested-by: Nathan Chancellor <nathan@...nel.org>
Signed-off-by: Will Deacon <will@...nel.org>
---
drivers/base/core.c | 2 +-
drivers/xen/swiotlb-xen.c | 4 ++--
include/linux/swiotlb.h | 2 +-
kernel/dma/swiotlb.c | 38 ++++++++++++++++++--------------------
4 files changed, 22 insertions(+), 24 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index ea5b85354526..b49824001cfa 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -2848,7 +2848,7 @@ void device_initialize(struct device *dev)
dev->dma_coherent = dma_default_coherent;
#endif
#ifdef CONFIG_SWIOTLB
- dev->dma_io_tlb_mem = io_tlb_default_mem;
+ dev->dma_io_tlb_mem = &io_tlb_default_mem;
#endif
}
EXPORT_SYMBOL_GPL(device_initialize);
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 785ec7e8be01..f06d9b4f1e0f 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -164,7 +164,7 @@ int __ref xen_swiotlb_init(void)
int rc = -ENOMEM;
char *start;
- if (io_tlb_default_mem != NULL) {
+ if (io_tlb_default_mem.nslabs) {
pr_warn("swiotlb buffer already initialized\n");
return -EEXIST;
}
@@ -547,7 +547,7 @@ xen_swiotlb_sync_sg_for_device(struct device *dev, struct scatterlist *sgl,
static int
xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
{
- return xen_phys_to_dma(hwdev, io_tlb_default_mem->end - 1) <= mask;
+ return xen_phys_to_dma(hwdev, io_tlb_default_mem.end - 1) <= mask;
}
const struct dma_map_ops xen_swiotlb_dma_ops = {
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index d3b617c19045..b0cb2a9973f4 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -105,7 +105,7 @@ struct io_tlb_mem {
unsigned int list;
} *slots;
};
-extern struct io_tlb_mem *io_tlb_default_mem;
+extern struct io_tlb_mem io_tlb_default_mem;
static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr)
{
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 992d73cdc944..7948f274f9bb 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -70,8 +70,7 @@
enum swiotlb_force swiotlb_force;
-struct io_tlb_mem *io_tlb_default_mem;
-static struct io_tlb_mem _io_tlb_default_mem;
+struct io_tlb_mem io_tlb_default_mem;
/*
* Max segment that we can provide which (if pages are contingous) will
@@ -102,7 +101,7 @@ early_param("swiotlb", setup_io_tlb_npages);
unsigned int swiotlb_max_segment(void)
{
- return io_tlb_default_mem ? max_segment : 0;
+ return io_tlb_default_mem.nslabs ? max_segment : 0;
}
EXPORT_SYMBOL_GPL(swiotlb_max_segment);
@@ -135,9 +134,9 @@ void __init swiotlb_adjust_size(unsigned long size)
void swiotlb_print_info(void)
{
- struct io_tlb_mem *mem = io_tlb_default_mem;
+ struct io_tlb_mem *mem = &io_tlb_default_mem;
- if (!mem) {
+ if (!mem->nslabs) {
pr_warn("No low mem\n");
return;
}
@@ -164,11 +163,11 @@ static inline unsigned long nr_slots(u64 val)
*/
void __init swiotlb_update_mem_attributes(void)
{
- struct io_tlb_mem *mem = io_tlb_default_mem;
+ struct io_tlb_mem *mem = &io_tlb_default_mem;
void *vaddr;
unsigned long bytes;
- if (!mem || mem->late_alloc)
+ if (!mem->nslabs || mem->late_alloc)
return;
vaddr = phys_to_virt(mem->start);
bytes = PAGE_ALIGN(mem->nslabs << IO_TLB_SHIFT);
@@ -202,14 +201,14 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
{
- struct io_tlb_mem *mem = &_io_tlb_default_mem;
+ struct io_tlb_mem *mem = &io_tlb_default_mem;
size_t alloc_size;
if (swiotlb_force == SWIOTLB_NO_FORCE)
return 0;
/* protect against double initialization */
- if (WARN_ON_ONCE(io_tlb_default_mem))
+ if (WARN_ON_ONCE(mem->nslabs))
return -ENOMEM;
alloc_size = PAGE_ALIGN(array_size(sizeof(*mem->slots), nslabs));
@@ -220,7 +219,6 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
swiotlb_init_io_tlb_mem(mem, __pa(tlb), nslabs, false);
- io_tlb_default_mem = mem;
if (verbose)
swiotlb_print_info();
swiotlb_set_max_segment(mem->nslabs << IO_TLB_SHIFT);
@@ -305,14 +303,14 @@ swiotlb_late_init_with_default_size(size_t default_size)
int
swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
{
- struct io_tlb_mem *mem = &_io_tlb_default_mem;
+ struct io_tlb_mem *mem = &io_tlb_default_mem;
unsigned long bytes = nslabs << IO_TLB_SHIFT;
if (swiotlb_force == SWIOTLB_NO_FORCE)
return 0;
/* protect against double initialization */
- if (WARN_ON_ONCE(io_tlb_default_mem))
+ if (WARN_ON_ONCE(mem->nslabs))
return -ENOMEM;
mem->slots = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
@@ -323,7 +321,6 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
set_memory_decrypted((unsigned long)tlb, bytes >> PAGE_SHIFT);
swiotlb_init_io_tlb_mem(mem, virt_to_phys(tlb), nslabs, true);
- io_tlb_default_mem = mem;
swiotlb_print_info();
swiotlb_set_max_segment(mem->nslabs << IO_TLB_SHIFT);
return 0;
@@ -331,10 +328,10 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
void __init swiotlb_exit(void)
{
- struct io_tlb_mem *mem = io_tlb_default_mem;
size_t size;
+ struct io_tlb_mem *mem = &io_tlb_default_mem;
- if (!mem)
+ if (!mem->nslabs)
return;
size = array_size(sizeof(*mem->slots), mem->nslabs);
@@ -342,7 +339,6 @@ void __init swiotlb_exit(void)
free_pages((unsigned long)mem->slots, get_order(size));
else
memblock_free_late(__pa(mem->slots), PAGE_ALIGN(size));
- io_tlb_default_mem = NULL;
memset(mem, 0, sizeof(*mem));
}
@@ -697,7 +693,9 @@ size_t swiotlb_max_mapping_size(struct device *dev)
bool is_swiotlb_active(struct device *dev)
{
- return dev->dma_io_tlb_mem != NULL;
+ struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+
+ return mem && mem->nslabs;
}
EXPORT_SYMBOL_GPL(is_swiotlb_active);
@@ -712,10 +710,10 @@ static void swiotlb_create_debugfs_files(struct io_tlb_mem *mem)
static int __init swiotlb_create_default_debugfs(void)
{
- struct io_tlb_mem *mem = io_tlb_default_mem;
+ struct io_tlb_mem *mem = &io_tlb_default_mem;
debugfs_dir = debugfs_create_dir("swiotlb", NULL);
- if (mem) {
+ if (mem->nslabs) {
mem->debugfs = debugfs_dir;
swiotlb_create_debugfs_files(mem);
}
@@ -814,7 +812,7 @@ static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
static void rmem_swiotlb_device_release(struct reserved_mem *rmem,
struct device *dev)
{
- dev->dma_io_tlb_mem = io_tlb_default_mem;
+ dev->dma_io_tlb_mem = &io_tlb_default_mem;
}
static const struct reserved_mem_ops rmem_swiotlb_ops = {
--
2.32.0.402.g57bb445576-goog
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