[PATCH 0/3] Some minor SWIOTLB cleanups

[PATCH 0/3] Some minor SWIOTLB cleanups

[Robin Murphy]

Hi all,

Here's a little collection of cleanup patches for some annoyances
that have built up while looking at SWIOTLB code recently.

Cheers,
Robin.


Robin Murphy (3):
  swiotlb: Simplify debugfs setup
  swiotlb: Tidy up includes
  swiotlb: Simplify array allocation

 kernel/dma/swiotlb.c | 74 ++++++++++++++------------------------------
 1 file changed, 24 insertions(+), 50 deletions(-)

-- 
2.28.0.dirty

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[PATCH 1/3] swiotlb: Simplify debugfs setup

[Robin Murphy]

Debugfs functions are already stubbed out for !CONFIG_DEBUG_FS, so we
can remove most of the #ifdefs, just keeping one to manually optimise
away the initcall when it would do nothing. We can also simplify the
code itself by factoring out the directory creation and realising that
the global io_tlb_default_mem now makes debugfs_dir redundant.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 kernel/dma/swiotlb.c | 40 ++++++++++------------------------------
 1 file changed, 10 insertions(+), 30 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index f1e7ea160b43..bdce89e053bd 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -36,9 +36,7 @@
 #include <linux/scatterlist.h>
 #include <linux/cc_platform.h>
 #include <linux/set_memory.h>
-#ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
-#endif
 #ifdef CONFIG_DMA_RESTRICTED_POOL
 #include <linux/io.h>
 #include <linux/of.h>
@@ -758,47 +756,29 @@ bool is_swiotlb_active(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(is_swiotlb_active);
 
-#ifdef CONFIG_DEBUG_FS
-static struct dentry *debugfs_dir;
-
-static void swiotlb_create_debugfs_files(struct io_tlb_mem *mem)
+static void swiotlb_create_debugfs_files(struct io_tlb_mem *mem,
+					 const char *dirname)
 {
+	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, &mem->used);
 }
 
-static int __init swiotlb_create_default_debugfs(void)
+static int __init __maybe_unused swiotlb_create_default_debugfs(void)
 {
-	struct io_tlb_mem *mem = &io_tlb_default_mem;
-
-	debugfs_dir = debugfs_create_dir("swiotlb", NULL);
-	if (mem->nslabs) {
-		mem->debugfs = debugfs_dir;
-		swiotlb_create_debugfs_files(mem);
-	}
+	swiotlb_create_debugfs_files(&io_tlb_default_mem, "swiotlb");
 	return 0;
 }
 
+#ifdef CONFIG_DEBUG_FS
 late_initcall(swiotlb_create_default_debugfs);
-
 #endif
 
 #ifdef CONFIG_DMA_RESTRICTED_POOL
 
-#ifdef CONFIG_DEBUG_FS
-static void rmem_swiotlb_debugfs_init(struct reserved_mem *rmem)
-{
-	struct io_tlb_mem *mem = rmem->priv;
-
-	mem->debugfs = debugfs_create_dir(rmem->name, debugfs_dir);
-	swiotlb_create_debugfs_files(mem);
-}
-#else
-static void rmem_swiotlb_debugfs_init(struct reserved_mem *rmem)
-{
-}
-#endif
-
 struct page *swiotlb_alloc(struct device *dev, size_t size)
 {
 	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
@@ -860,7 +840,7 @@ static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
 
 		rmem->priv = mem;
 
-		rmem_swiotlb_debugfs_init(rmem);
+		swiotlb_create_debugfs_files(mem, rmem->name);
 	}
 
 	dev->dma_io_tlb_mem = mem;
-- 
2.28.0.dirty

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[PATCH 2/3] swiotlb: Tidy up includes

[Robin Murphy]

SWIOTLB's includes have become a great big mess. Restore some order by
consolidating the random different blocks, sorting alphabetically, and
purging some clearly unnecessary entries - linux/io.h is now included
unconditionally, so need not be duplicated in the restricted DMA pool
case; similarly, linux/io.h subsumes asm/io.h; and by now it's a
mystery why asm/dma.h was ever here at all.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 kernel/dma/swiotlb.c | 31 +++++++++++++------------------
 1 file changed, 13 insertions(+), 18 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index bdce89e053bd..f56d6504903c 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -21,38 +21,33 @@
 #define pr_fmt(fmt) "software IO TLB: " fmt
 
 #include <linux/cache.h>
+#include <linux/cc_platform.h>
+#include <linux/ctype.h>
+#include <linux/debugfs.h>
 #include <linux/dma-direct.h>
 #include <linux/dma-map-ops.h>
-#include <linux/mm.h>
 #include <linux/export.h>
+#include <linux/gfp.h>
+#include <linux/highmem.h>
+#include <linux/io.h>
+#include <linux/iommu-helper.h>
+#include <linux/init.h>
+#include <linux/memblock.h>
+#include <linux/mm.h>
+#include <linux/pfn.h>
+#include <linux/scatterlist.h>
+#include <linux/set_memory.h>
 #include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/swiotlb.h>
-#include <linux/pfn.h>
 #include <linux/types.h>
-#include <linux/ctype.h>
-#include <linux/highmem.h>
-#include <linux/gfp.h>
-#include <linux/scatterlist.h>
-#include <linux/cc_platform.h>
-#include <linux/set_memory.h>
-#include <linux/debugfs.h>
 #ifdef CONFIG_DMA_RESTRICTED_POOL
-#include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/slab.h>
 #endif
 
-#include <asm/io.h>
-#include <asm/dma.h>
-
-#include <linux/io.h>
-#include <linux/init.h>
-#include <linux/memblock.h>
-#include <linux/iommu-helper.h>
-
 #define CREATE_TRACE_POINTS
 #include <trace/events/swiotlb.h>
 
-- 
2.28.0.dirty

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[PATCH 3/3] swiotlb: Simplify array allocation

[Robin Murphy]

Prefer kcalloc() to kzalloc(array_size()) for allocating an array.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 kernel/dma/swiotlb.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index f56d6504903c..44c49c3616fe 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -820,8 +820,7 @@ static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
 		if (!mem)
 			return -ENOMEM;
 
-		mem->slots = kzalloc(array_size(sizeof(*mem->slots), nslabs),
-				     GFP_KERNEL);
+		mem->slots = kcalloc(nslabs, sizeof(*mem->slots), GFP_KERNEL);
 		if (!mem->slots) {
 			kfree(mem);
 			return -ENOMEM;
-- 
2.28.0.dirty

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Re: [PATCH 0/3] Some minor SWIOTLB cleanups

[Christoph Hellwig]

Thanks,

applied to the dma-mapping for-next tree.
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