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Message-Id: <20220722033846.950237-1-ltykernel@gmail.com>
Date: Thu, 21 Jul 2022 23:38:46 -0400
From: Tianyu Lan <ltykernel@...il.com>
To: hch@...radead.org, m.szyprowski@...sung.com, robin.murphy@....com,
michael.h.kelley@...rosoft.com
Cc: Tianyu Lan <tiala@...rosoft.com>, iommu@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org
Subject: [PATCH] swiotlb: Clean up some coding style and minor issues
From: Tianyu Lan <tiala@...rosoft.com>
- Fix the used field of struct io_tlb_area wasn't initialized
- Set area number to be 0 if input area number parameter is 0
- Use array_size() to calculate io_tlb_area array size
- Fix error handle of io_tlb_used debugfs node and introduce
fops_io_tlb_used attribute
- Make parameters of swiotlb_do_find_slots() more reasonable
Fixes: 26ffb91fa5e0 ("swiotlb: split up the global swiotlb lock")
Signed-off-by: Tianyu Lan <tiala@...rosoft.com>
---
.../admin-guide/kernel-parameters.txt | 3 +-
kernel/dma/swiotlb.c | 42 ++++++++++++-------
2 files changed, 30 insertions(+), 15 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 4a6ad177d4b8..ddca09550f76 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5907,7 +5907,8 @@
Format: { <int> [,<int>] | force | noforce }
<int> -- Number of I/O TLB slabs
<int> -- Second integer after comma. Number of swiotlb
- areas with their own lock. Must be power of 2.
+ areas with their own lock. Will be rounded up
+ to a power of 2.
force -- force using of bounce buffers even if they
wouldn't be automatically used by the kernel
noforce -- Never use bounce buffers (for debugging)
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index c39483bf067d..5752db98a1f2 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -96,7 +96,13 @@ struct io_tlb_slot {
static void swiotlb_adjust_nareas(unsigned int nareas)
{
- if (!is_power_of_2(nareas))
+ /*
+ * Set area number to 1 when input area number
+ * is zero.
+ */
+ if (!nareas)
+ nareas = 1;
+ else if (!is_power_of_2(nareas))
nareas = roundup_pow_of_two(nareas);
default_nareas = nareas;
@@ -270,6 +276,7 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
for (i = 0; i < mem->nareas; i++) {
spin_lock_init(&mem->areas[i].lock);
mem->areas[i].index = 0;
+ mem->areas[i].used = 0;
}
for (i = 0; i < mem->nslabs; i++) {
@@ -353,8 +360,8 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags,
panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
__func__, alloc_size, PAGE_SIZE);
- mem->areas = memblock_alloc(sizeof(struct io_tlb_area) *
- default_nareas, SMP_CACHE_BYTES);
+ mem->areas = memblock_alloc(array_size(sizeof(struct io_tlb_area),
+ default_nareas), SMP_CACHE_BYTES);
if (!mem->areas)
panic("%s: Failed to allocate mem->areas.\n", __func__);
@@ -479,7 +486,7 @@ void __init swiotlb_exit(void)
free_pages((unsigned long)mem->slots, get_order(slots_size));
} else {
memblock_free_late(__pa(mem->areas),
- mem->nareas * sizeof(struct io_tlb_area));
+ array_size(sizeof(*mem->areas), mem->nareas));
memblock_free_late(mem->start, tbl_size);
memblock_free_late(__pa(mem->slots), slots_size);
}
@@ -593,11 +600,12 @@ static unsigned int wrap_area_index(struct io_tlb_mem *mem, unsigned int index)
* Find a suitable number of IO TLB entries size that will fit this request and
* allocate a buffer from that IO TLB pool.
*/
-static int swiotlb_do_find_slots(struct io_tlb_mem *mem,
- struct io_tlb_area *area, int area_index,
- struct device *dev, phys_addr_t orig_addr,
+static int swiotlb_do_find_slots(struct device *dev,
+ int area_index, phys_addr_t orig_addr,
size_t alloc_size, unsigned int alloc_align_mask)
{
+ struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+ struct io_tlb_area *area = mem->areas + area_index;
unsigned long boundary_mask = dma_get_seg_boundary(dev);
dma_addr_t tbl_dma_addr =
phys_to_dma_unencrypted(dev, mem->start) & boundary_mask;
@@ -686,13 +694,12 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
size_t alloc_size, unsigned int alloc_align_mask)
{
struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
- int start = raw_smp_processor_id() & ((1U << __fls(mem->nareas)) - 1);
+ int start = raw_smp_processor_id() & (mem->nareas - 1);
int i = start, index;
do {
- index = swiotlb_do_find_slots(mem, mem->areas + i, i,
- dev, orig_addr, alloc_size,
- alloc_align_mask);
+ index = swiotlb_do_find_slots(dev, i, orig_addr,
+ alloc_size, alloc_align_mask);
if (index >= 0)
return index;
if (++i >= mem->nareas)
@@ -903,17 +910,24 @@ bool is_swiotlb_active(struct device *dev)
}
EXPORT_SYMBOL_GPL(is_swiotlb_active);
+static int io_tlb_used_get(void *data, u64 *val)
+{
+ *val = mem_used(&io_tlb_default_mem);
+
+ return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(fops_io_tlb_used, io_tlb_used_get, NULL, "%llu\n");
+
static void swiotlb_create_debugfs_files(struct io_tlb_mem *mem,
const char *dirname)
{
- unsigned long used = mem_used(mem);
-
mem->debugfs = debugfs_create_dir(dirname, io_tlb_default_mem.debugfs);
if (!mem->nslabs)
return;
debugfs_create_ulong("io_tlb_nslabs", 0400, mem->debugfs, &mem->nslabs);
- debugfs_create_ulong("io_tlb_used", 0400, mem->debugfs, &used);
+ debugfs_create_file_unsafe("io_tlb_used", 0400, mem->debugfs, NULL,
+ &fops_io_tlb_used);
}
static int __init __maybe_unused swiotlb_create_default_debugfs(void)
--
2.25.1
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