dma-debug cleanups, including removing the arch hook

dma-debug cleanups, including removing the arch hook

[Christoph Hellwig]

Hi all,

this series has a few dma-debug cleanups, most notably removing the need
for architectures to explicitly initialize dma-debug.

[PATCH 1/3] dma-debug: move initialization to common code

[Christoph Hellwig]

Most mainstream architectures are using 65536 entries, so lets stick to
that.  If someone is really desperate to override it that can still be
done through <asm/dma-mapping.h>, but I'd rather see a really good
rationale for that.

dma_debug_init is now called as a core_initcall, which for many
architectures means much earlier, and provides dma-debug functionality
earlier in the boot process.  This should be safe as it only relies
on the memory allocator already being available.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm/mm/dma-mapping-nommu.c |  9 ---------
 arch/arm/mm/dma-mapping.c       |  9 ---------
 arch/arm64/mm/dma-mapping.c     | 10 ----------
 arch/c6x/kernel/dma.c           | 11 -----------
 arch/ia64/kernel/dma-mapping.c  | 10 ----------
 arch/microblaze/kernel/dma.c    | 11 -----------
 arch/mips/mm/dma-default.c      | 10 ----------
 arch/openrisc/kernel/dma.c      | 11 -----------
 arch/powerpc/kernel/dma.c       |  3 ---
 arch/s390/pci/pci_dma.c         |  9 ---------
 arch/sh/mm/consistent.c         |  9 ---------
 arch/sparc/kernel/Makefile      |  2 --
 arch/sparc/kernel/dma.c         | 13 -------------
 arch/x86/kernel/pci-dma.c       |  4 ----
 arch/xtensa/kernel/pci-dma.c    |  9 ---------
 include/linux/dma-debug.h       |  6 ------
 lib/dma-debug.c                 | 21 ++++++++++++++-------
 17 files changed, 14 insertions(+), 143 deletions(-)
 delete mode 100644 arch/sparc/kernel/dma.c

diff --git a/arch/arm/mm/dma-mapping-nommu.c b/arch/arm/mm/dma-mapping-nommu.c
index 619f24a42d09..f448a0663b10 100644
--- a/arch/arm/mm/dma-mapping-nommu.c
+++ b/arch/arm/mm/dma-mapping-nommu.c
@@ -241,12 +241,3 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 void arch_teardown_dma_ops(struct device *dev)
 {
 }
-
-#define PREALLOC_DMA_DEBUG_ENTRIES	4096
-
-static int __init dma_debug_do_init(void)
-{
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
-	return 0;
-}
-core_initcall(dma_debug_do_init);
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 8c398fedbbb6..c26bf83f44ca 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1165,15 +1165,6 @@ int arm_dma_supported(struct device *dev, u64 mask)
 	return __dma_supported(dev, mask, false);
 }
 
-#define PREALLOC_DMA_DEBUG_ENTRIES	4096
-
-static int __init dma_debug_do_init(void)
-{
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
-	return 0;
-}
-core_initcall(dma_debug_do_init);
-
 #ifdef CONFIG_ARM_DMA_USE_IOMMU
 
 static int __dma_info_to_prot(enum dma_data_direction dir, unsigned long attrs)
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index a96ec0181818..db01f2709842 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -508,16 +508,6 @@ static int __init arm64_dma_init(void)
 }
 arch_initcall(arm64_dma_init);
 
-#define PREALLOC_DMA_DEBUG_ENTRIES	4096
-
-static int __init dma_debug_do_init(void)
-{
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
-	return 0;
-}
-fs_initcall(dma_debug_do_init);
-
-
 #ifdef CONFIG_IOMMU_DMA
 #include <linux/dma-iommu.h>
 #include <linux/platform_device.h>
diff --git a/arch/c6x/kernel/dma.c b/arch/c6x/kernel/dma.c
index 9fff8be75f58..31e1a9ec3a9c 100644
--- a/arch/c6x/kernel/dma.c
+++ b/arch/c6x/kernel/dma.c
@@ -136,14 +136,3 @@ const struct dma_map_ops c6x_dma_ops = {
 	.sync_sg_for_cpu	= c6x_dma_sync_sg_for_cpu,
 };
 EXPORT_SYMBOL(c6x_dma_ops);
-
-/* Number of entries preallocated for DMA-API debugging */
-#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
-
-static int __init dma_init(void)
-{
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
-
-	return 0;
-}
-fs_initcall(dma_init);
diff --git a/arch/ia64/kernel/dma-mapping.c b/arch/ia64/kernel/dma-mapping.c
index f2d57e66fd86..7a471d8d67d4 100644
--- a/arch/ia64/kernel/dma-mapping.c
+++ b/arch/ia64/kernel/dma-mapping.c
@@ -9,16 +9,6 @@ int iommu_detected __read_mostly;
 const struct dma_map_ops *dma_ops;
 EXPORT_SYMBOL(dma_ops);
 
-#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
-
-static int __init dma_init(void)
-{
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
-
-	return 0;
-}
-fs_initcall(dma_init);
-
 const struct dma_map_ops *dma_get_ops(struct device *dev)
 {
 	return dma_ops;
diff --git a/arch/microblaze/kernel/dma.c b/arch/microblaze/kernel/dma.c
index c91e8cef98dd..3145e7dc8ab1 100644
--- a/arch/microblaze/kernel/dma.c
+++ b/arch/microblaze/kernel/dma.c
@@ -184,14 +184,3 @@ const struct dma_map_ops dma_nommu_ops = {
 	.sync_sg_for_device	= dma_nommu_sync_sg_for_device,
 };
 EXPORT_SYMBOL(dma_nommu_ops);
-
-/* Number of entries preallocated for DMA-API debugging */
-#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
-
-static int __init dma_init(void)
-{
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
-
-	return 0;
-}
-fs_initcall(dma_init);
diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
index dcafa43613b6..f9fef0028ca2 100644
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -402,13 +402,3 @@ static const struct dma_map_ops mips_default_dma_map_ops = {
 
 const struct dma_map_ops *mips_dma_map_ops = &mips_default_dma_map_ops;
 EXPORT_SYMBOL(mips_dma_map_ops);
-
-#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
-
-static int __init mips_dma_init(void)
-{
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
-
-	return 0;
-}
-fs_initcall(mips_dma_init);
diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c
index a945f00011b4..ec7fd45704d2 100644
--- a/arch/openrisc/kernel/dma.c
+++ b/arch/openrisc/kernel/dma.c
@@ -247,14 +247,3 @@ const struct dma_map_ops or1k_dma_map_ops = {
 	.sync_single_for_device = or1k_sync_single_for_device,
 };
 EXPORT_SYMBOL(or1k_dma_map_ops);
-
-/* Number of entries preallocated for DMA-API debugging */
-#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
-
-static int __init dma_init(void)
-{
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
-
-	return 0;
-}
-fs_initcall(dma_init);
diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index da20569de9d4..138157deeadf 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -309,8 +309,6 @@ int dma_set_coherent_mask(struct device *dev, u64 mask)
 }
 EXPORT_SYMBOL(dma_set_coherent_mask);
 
-#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
-
 int dma_set_mask(struct device *dev, u64 dma_mask)
 {
 	if (ppc_md.dma_set_mask)
@@ -361,7 +359,6 @@ EXPORT_SYMBOL_GPL(dma_get_required_mask);
 
 static int __init dma_init(void)
 {
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
 #ifdef CONFIG_PCI
 	dma_debug_add_bus(&pci_bus_type);
 #endif
diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
index 2d15d84c20ed..5dee7a922589 100644
--- a/arch/s390/pci/pci_dma.c
+++ b/arch/s390/pci/pci_dma.c
@@ -668,15 +668,6 @@ void zpci_dma_exit(void)
 	kmem_cache_destroy(dma_region_table_cache);
 }
 
-#define PREALLOC_DMA_DEBUG_ENTRIES	(1 << 16)
-
-static int __init dma_debug_do_init(void)
-{
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
-	return 0;
-}
-fs_initcall(dma_debug_do_init);
-
 const struct dma_map_ops s390_pci_dma_ops = {
 	.alloc		= s390_dma_alloc,
 	.free		= s390_dma_free,
diff --git a/arch/sh/mm/consistent.c b/arch/sh/mm/consistent.c
index 8ce98691d822..35ea3099a3b6 100644
--- a/arch/sh/mm/consistent.c
+++ b/arch/sh/mm/consistent.c
@@ -20,18 +20,9 @@
 #include <asm/cacheflush.h>
 #include <asm/addrspace.h>
 
-#define PREALLOC_DMA_DEBUG_ENTRIES	4096
-
 const struct dma_map_ops *dma_ops;
 EXPORT_SYMBOL(dma_ops);
 
-static int __init dma_init(void)
-{
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
-	return 0;
-}
-fs_initcall(dma_init);
-
 void *dma_generic_alloc_coherent(struct device *dev, size_t size,
 				 dma_addr_t *dma_handle, gfp_t gfp,
 				 unsigned long attrs)
diff --git a/arch/sparc/kernel/Makefile b/arch/sparc/kernel/Makefile
index 76cb57750dda..84cfc5a428d6 100644
--- a/arch/sparc/kernel/Makefile
+++ b/arch/sparc/kernel/Makefile
@@ -74,8 +74,6 @@ obj-$(CONFIG_SPARC64)	+= pcr.o
 obj-$(CONFIG_SPARC64)	+= nmi.o
 obj-$(CONFIG_SPARC64_SMP) += cpumap.o
 
-obj-y                     += dma.o
-
 obj-$(CONFIG_PCIC_PCI)    += pcic.o
 obj-$(CONFIG_LEON_PCI)    += leon_pci.o
 obj-$(CONFIG_SPARC_GRPCI2)+= leon_pci_grpci2.o
diff --git a/arch/sparc/kernel/dma.c b/arch/sparc/kernel/dma.c
deleted file mode 100644
index f73e7597c971..000000000000
--- a/arch/sparc/kernel/dma.c
+++ /dev/null
@@ -1,13 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include <linux/kernel.h>
-#include <linux/dma-mapping.h>
-#include <linux/dma-debug.h>
-
-#define PREALLOC_DMA_DEBUG_ENTRIES       (1 << 15)
-
-static int __init dma_init(void)
-{
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
-	return 0;
-}
-fs_initcall(dma_init);
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 77625b60a510..bcbaa2e8031e 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -55,9 +55,6 @@ struct device x86_dma_fallback_dev = {
 };
 EXPORT_SYMBOL(x86_dma_fallback_dev);
 
-/* Number of entries preallocated for DMA-API debugging */
-#define PREALLOC_DMA_DEBUG_ENTRIES       65536
-
 void __init pci_iommu_alloc(void)
 {
 	struct iommu_table_entry *p;
@@ -189,7 +186,6 @@ EXPORT_SYMBOL(arch_dma_supported);
 static int __init pci_iommu_init(void)
 {
 	struct iommu_table_entry *p;
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
 
 #ifdef CONFIG_PCI
 	dma_debug_add_bus(&pci_bus_type);
diff --git a/arch/xtensa/kernel/pci-dma.c b/arch/xtensa/kernel/pci-dma.c
index 732631ce250f..392b4a80ebc2 100644
--- a/arch/xtensa/kernel/pci-dma.c
+++ b/arch/xtensa/kernel/pci-dma.c
@@ -261,12 +261,3 @@ const struct dma_map_ops xtensa_dma_map_ops = {
 	.mapping_error = xtensa_dma_mapping_error,
 };
 EXPORT_SYMBOL(xtensa_dma_map_ops);
-
-#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
-
-static int __init xtensa_dma_init(void)
-{
-	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
-	return 0;
-}
-fs_initcall(xtensa_dma_init);
diff --git a/include/linux/dma-debug.h b/include/linux/dma-debug.h
index c7d844f09c3a..a785f2507159 100644
--- a/include/linux/dma-debug.h
+++ b/include/linux/dma-debug.h
@@ -30,8 +30,6 @@ struct bus_type;
 
 extern void dma_debug_add_bus(struct bus_type *bus);
 
-extern void dma_debug_init(u32 num_entries);
-
 extern int dma_debug_resize_entries(u32 num_entries);
 
 extern void debug_dma_map_page(struct device *dev, struct page *page,
@@ -100,10 +98,6 @@ static inline void dma_debug_add_bus(struct bus_type *bus)
 {
 }
 
-static inline void dma_debug_init(u32 num_entries)
-{
-}
-
 static inline int dma_debug_resize_entries(u32 num_entries)
 {
 	return 0;
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 7f5cdc1e6b29..712a897174e4 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -41,6 +41,11 @@
 #define HASH_FN_SHIFT   13
 #define HASH_FN_MASK    (HASH_SIZE - 1)
 
+/* allow architectures to override this if absolutely required */
+#ifndef PREALLOC_DMA_DEBUG_ENTRIES
+#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
+#endif
+
 enum {
 	dma_debug_single,
 	dma_debug_page,
@@ -1004,18 +1009,16 @@ void dma_debug_add_bus(struct bus_type *bus)
 	bus_register_notifier(bus, nb);
 }
 
-/*
- * Let the architectures decide how many entries should be preallocated.
- */
-void dma_debug_init(u32 num_entries)
+static int dma_debug_init(void)
 {
+	u32 num_entries;
 	int i;
 
 	/* Do not use dma_debug_initialized here, since we really want to be
 	 * called to set dma_debug_initialized
 	 */
 	if (global_disable)
-		return;
+		return 0;
 
 	for (i = 0; i < HASH_SIZE; ++i) {
 		INIT_LIST_HEAD(&dma_entry_hash[i].list);
@@ -1026,17 +1029,19 @@ void dma_debug_init(u32 num_entries)
 		pr_err("DMA-API: error creating debugfs entries - disabling\n");
 		global_disable = true;
 
-		return;
+		return 0;
 	}
 
 	if (req_entries)
 		num_entries = req_entries;
+	else
+		num_entries = PREALLOC_DMA_DEBUG_ENTRIES;
 
 	if (prealloc_memory(num_entries) != 0) {
 		pr_err("DMA-API: debugging out of memory error - disabled\n");
 		global_disable = true;
 
-		return;
+		return 0;
 	}
 
 	nr_total_entries = num_free_entries;
@@ -1044,7 +1049,9 @@ void dma_debug_init(u32 num_entries)
 	dma_debug_initialized = true;
 
 	pr_info("DMA-API: debugging enabled by kernel config\n");
+	return 0;
 }
+core_initcall(dma_debug_init);
 
 static __init int dma_debug_cmdline(char *str)
 {
-- 
2.17.0

[PATCH 2/3] dma-debug: simplify counting of preallocated requests

[Christoph Hellwig]

Just keep a single variable with a descriptive name instead of two
with confusing names.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 lib/dma-debug.c | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 712a897174e4..075253cb613b 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -132,7 +132,7 @@ static u32 min_free_entries;
 static u32 nr_total_entries;
 
 /* number of preallocated entries requested by kernel cmdline */
-static u32 req_entries;
+static u32 nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
 
 /* debugfs dentry's for the stuff above */
 static struct dentry *dma_debug_dent        __read_mostly;
@@ -1011,7 +1011,6 @@ void dma_debug_add_bus(struct bus_type *bus)
 
 static int dma_debug_init(void)
 {
-	u32 num_entries;
 	int i;
 
 	/* Do not use dma_debug_initialized here, since we really want to be
@@ -1032,12 +1031,7 @@ static int dma_debug_init(void)
 		return 0;
 	}
 
-	if (req_entries)
-		num_entries = req_entries;
-	else
-		num_entries = PREALLOC_DMA_DEBUG_ENTRIES;
-
-	if (prealloc_memory(num_entries) != 0) {
+	if (prealloc_memory(nr_prealloc_entries) != 0) {
 		pr_err("DMA-API: debugging out of memory error - disabled\n");
 		global_disable = true;
 
@@ -1068,16 +1062,10 @@ static __init int dma_debug_cmdline(char *str)
 
 static __init int dma_debug_entries_cmdline(char *str)
 {
-	int res;
-
 	if (!str)
 		return -EINVAL;
-
-	res = get_option(&str, &req_entries);
-
-	if (!res)
-		req_entries = 0;
-
+	if (!get_option(&str, &nr_prealloc_entries))
+		nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
 	return 0;
 }
 
-- 
2.17.0

[PATCH 3/3] dma-debug: unexport dma_debug_resize_entries and debug_dma_dump_mappings

[Christoph Hellwig]

Only used by the AMD GART driver, which must be built in.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 lib/dma-debug.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 075253cb613b..6a1ebaa83623 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -444,7 +444,6 @@ void debug_dma_dump_mappings(struct device *dev)
 		spin_unlock_irqrestore(&bucket->lock, flags);
 	}
 }
-EXPORT_SYMBOL(debug_dma_dump_mappings);
 
 /*
  * For each mapping (initial cacheline in the case of
@@ -753,7 +752,6 @@ int dma_debug_resize_entries(u32 num_entries)
 
 	return ret;
 }
-EXPORT_SYMBOL(dma_debug_resize_entries);
 
 /*
  * DMA-API debugging init code
-- 
2.17.0

[PATCH 4/3] dma-debug: remove CONFIG_HAVE_DMA_API_DEBUG

[Christoph Hellwig]

There is no arch specific code required for dma-debug, so there is no
need to opt into the support either.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 .../io/dma-api-debug/arch-support.txt         | 31 -------------------
 arch/Kconfig                                  |  3 --
 arch/arm/Kconfig                              |  1 -
 arch/arm64/Kconfig                            |  1 -
 arch/c6x/Kconfig                              |  1 -
 arch/ia64/Kconfig                             |  1 -
 arch/microblaze/Kconfig                       |  1 -
 arch/mips/Kconfig                             |  1 -
 arch/powerpc/Kconfig                          |  1 -
 arch/riscv/Kconfig                            |  1 -
 arch/s390/Kconfig                             |  1 -
 arch/sh/Kconfig                               |  1 -
 arch/sparc/Kconfig                            |  1 -
 arch/x86/Kconfig                              |  1 -
 arch/xtensa/Kconfig                           |  1 -
 lib/Kconfig.debug                             |  1 -
 16 files changed, 48 deletions(-)
 delete mode 100644 Documentation/features/io/dma-api-debug/arch-support.txt

diff --git a/Documentation/features/io/dma-api-debug/arch-support.txt b/Documentation/features/io/dma-api-debug/arch-support.txt
deleted file mode 100644
index e438ed675623..000000000000
--- a/Documentation/features/io/dma-api-debug/arch-support.txt
+++ /dev/null
@@ -1,31 +0,0 @@
-#
-# Feature name:          dma-api-debug
-#         Kconfig:       HAVE_DMA_API_DEBUG
-#         description:   arch supports DMA debug facilities
-#
-    -----------------------
-    |         arch |status|
-    -----------------------
-    |       alpha: | TODO |
-    |         arc: | TODO |
-    |         arm: |  ok  |
-    |       arm64: |  ok  |
-    |         c6x: |  ok  |
-    |       h8300: | TODO |
-    |     hexagon: | TODO |
-    |        ia64: |  ok  |
-    |        m68k: | TODO |
-    |  microblaze: |  ok  |
-    |        mips: |  ok  |
-    |       nios2: | TODO |
-    |    openrisc: | TODO |
-    |      parisc: | TODO |
-    |     powerpc: |  ok  |
-    |        s390: |  ok  |
-    |          sh: |  ok  |
-    |       sparc: |  ok  |
-    |          um: | TODO |
-    |   unicore32: | TODO |
-    |         x86: |  ok  |
-    |      xtensa: |  ok  |
-    -----------------------
diff --git a/arch/Kconfig b/arch/Kconfig
index 8e0d665c8d53..f07a1a99e5db 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -278,9 +278,6 @@ config HAVE_CLK
 	  The <linux/clk.h> calls support software clock gating and
 	  thus are a key power management tool on many systems.
 
-config HAVE_DMA_API_DEBUG
-	bool
-
 config HAVE_HW_BREAKPOINT
 	bool
 	depends on PERF_EVENTS
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 676977bdfe33..c43f5bb55ac8 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -60,7 +60,6 @@ config ARM
 	select HAVE_CONTEXT_TRACKING
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_DEBUG_KMEMLEAK
-	select HAVE_DMA_API_DEBUG
 	select HAVE_DMA_CONTIGUOUS if MMU
 	select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL) && !CPU_ENDIAN_BE32 && MMU
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index db51b6445744..b25ed7834f6c 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -105,7 +105,6 @@ config ARM64
 	select HAVE_CONTEXT_TRACKING
 	select HAVE_DEBUG_BUGVERBOSE
 	select HAVE_DEBUG_KMEMLEAK
-	select HAVE_DMA_API_DEBUG
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
diff --git a/arch/c6x/Kconfig b/arch/c6x/Kconfig
index c6b4dd1418b4..8c088b96e372 100644
--- a/arch/c6x/Kconfig
+++ b/arch/c6x/Kconfig
@@ -10,7 +10,6 @@ config C6X
 	select GENERIC_ATOMIC64
 	select GENERIC_IRQ_SHOW
 	select HAVE_ARCH_TRACEHOOK
-	select HAVE_DMA_API_DEBUG
 	select HAVE_MEMBLOCK
 	select SPARSE_IRQ
 	select IRQ_DOMAIN
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 9485b5490eca..2067289fad4a 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -29,7 +29,6 @@ config IA64
 	select HAVE_FUNCTION_TRACER
 	select TTY
 	select HAVE_ARCH_TRACEHOOK
-	select HAVE_DMA_API_DEBUG
 	select HAVE_MEMBLOCK
 	select HAVE_MEMBLOCK_NODE_MAP
 	select HAVE_VIRT_CPU_ACCOUNTING
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index 3817a3e2146c..d14782100088 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -19,7 +19,6 @@ config MICROBLAZE
 	select HAVE_ARCH_HASH
 	select HAVE_ARCH_KGDB
 	select HAVE_DEBUG_KMEMLEAK
-	select HAVE_DMA_API_DEBUG
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FUNCTION_GRAPH_TRACER
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 0f619b8c0e9e..2dcdc13cd65d 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -42,7 +42,6 @@ config MIPS
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DEBUG_STACKOVERFLOW
-	select HAVE_DMA_API_DEBUG
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_EXIT_THREAD
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 1887f8f86a77..268fd46fc3c7 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -181,7 +181,6 @@ config PPC
 	select HAVE_CONTEXT_TRACKING		if PPC64
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DEBUG_STACKOVERFLOW
-	select HAVE_DMA_API_DEBUG
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS	if MPROFILE_KERNEL
 	select HAVE_EBPF_JIT			if PPC64
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 17212ba54ee3..95e2da34aaad 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -23,7 +23,6 @@ config RISCV
 	select GENERIC_ATOMIC64 if !64BIT || !RISCV_ISA_A
 	select HAVE_MEMBLOCK
 	select HAVE_MEMBLOCK_NODE_MAP
-	select HAVE_DMA_API_DEBUG
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_GENERIC_DMA_COHERENT
 	select IRQ_DOMAIN
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index b794a2ab6d15..6a64287ec1da 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -130,7 +130,6 @@ config S390
 	select HAVE_CMPXCHG_LOCAL
 	select HAVE_COPY_THREAD_TLS
 	select HAVE_DEBUG_KMEMLEAK
-	select HAVE_DMA_API_DEBUG
 	select HAVE_DMA_CONTIGUOUS
 	select DMA_DIRECT_OPS
 	select HAVE_DYNAMIC_FTRACE
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 9417f70e008e..7d521926041e 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -13,7 +13,6 @@ config SUPERH
 	select HAVE_OPROFILE
 	select HAVE_GENERIC_DMA_COHERENT
 	select HAVE_ARCH_TRACEHOOK
-	select HAVE_DMA_API_DEBUG
 	select HAVE_PERF_EVENTS
 	select HAVE_DEBUG_BUGVERBOSE
 	select ARCH_HAVE_CUSTOM_GPIO_H
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index c1cfc17eb504..435dbc033afe 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -25,7 +25,6 @@ config SPARC
 	select RTC_CLASS
 	select RTC_DRV_M48T59
 	select RTC_SYSTOHC
-	select HAVE_DMA_API_DEBUG
 	select HAVE_ARCH_JUMP_LABEL if SPARC64
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_IPC_PARSE_VERSION
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index aad35c568681..3eeca48a146b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -135,7 +135,6 @@ config X86
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DEBUG_STACKOVERFLOW
-	select HAVE_DMA_API_DEBUG
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index c921e8bccdc8..17df332269b2 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -19,7 +19,6 @@ config XTENSA
 	select HAVE_ARCH_KASAN if MMU
 	select HAVE_CC_STACKPROTECTOR
 	select HAVE_DEBUG_KMEMLEAK
-	select HAVE_DMA_API_DEBUG
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_EXIT_THREAD
 	select HAVE_FUNCTION_TRACER
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 685ed2dd4384..d5175eb7b917 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1634,7 +1634,6 @@ config PROVIDE_OHCI1394_DMA_INIT
 
 config DMA_API_DEBUG
 	bool "Enable debugging of DMA-API usage"
-	depends on HAVE_DMA_API_DEBUG
 	select NEED_DMA_MAP_STATE
 	help
 	  Enable this option to debug the use of the DMA API by device drivers.
-- 
2.17.0

Re: dma-debug cleanups, including removing the arch hook

[Christoph Hellwig]

Any comments?  I'd like to move forward with this rather sooner
than later, so any reviews welcome!

On Tue, Apr 24, 2018 at 04:02:32PM +0200, Christoph Hellwig wrote:
> Hi all,
> 
> this series has a few dma-debug cleanups, most notably removing the need
> for architectures to explicitly initialize dma-debug.
> _______________________________________________
> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
---end quoted text---

Re: [PATCH 1/3] dma-debug: move initialization to common code

[Robin Murphy]

On 24/04/18 15:02, Christoph Hellwig wrote:
> Most mainstream architectures are using 65536 entries, so lets stick to
> that.  If someone is really desperate to override it that can still be
> done through <asm/dma-mapping.h>, but I'd rather see a really good
> rationale for that.
> 
> dma_debug_init is now called as a core_initcall, which for many
> architectures means much earlier, and provides dma-debug functionality
> earlier in the boot process.  This should be safe as it only relies
> on the memory allocator already being available.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   arch/arm/mm/dma-mapping-nommu.c |  9 ---------
>   arch/arm/mm/dma-mapping.c       |  9 ---------
>   arch/arm64/mm/dma-mapping.c     | 10 ----------
>   arch/c6x/kernel/dma.c           | 11 -----------
>   arch/ia64/kernel/dma-mapping.c  | 10 ----------
>   arch/microblaze/kernel/dma.c    | 11 -----------
>   arch/mips/mm/dma-default.c      | 10 ----------
>   arch/openrisc/kernel/dma.c      | 11 -----------
>   arch/powerpc/kernel/dma.c       |  3 ---
>   arch/s390/pci/pci_dma.c         |  9 ---------
>   arch/sh/mm/consistent.c         |  9 ---------
>   arch/sparc/kernel/Makefile      |  2 --
>   arch/sparc/kernel/dma.c         | 13 -------------
>   arch/x86/kernel/pci-dma.c       |  4 ----
>   arch/xtensa/kernel/pci-dma.c    |  9 ---------
>   include/linux/dma-debug.h       |  6 ------
>   lib/dma-debug.c                 | 21 ++++++++++++++-------
>   17 files changed, 14 insertions(+), 143 deletions(-)
>   delete mode 100644 arch/sparc/kernel/dma.c
> 
> diff --git a/arch/arm/mm/dma-mapping-nommu.c b/arch/arm/mm/dma-mapping-nommu.c
> index 619f24a42d09..f448a0663b10 100644
> --- a/arch/arm/mm/dma-mapping-nommu.c
> +++ b/arch/arm/mm/dma-mapping-nommu.c
> @@ -241,12 +241,3 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
>   void arch_teardown_dma_ops(struct device *dev)
>   {
>   }
> -
> -#define PREALLOC_DMA_DEBUG_ENTRIES	4096
> -
> -static int __init dma_debug_do_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -core_initcall(dma_debug_do_init);
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index 8c398fedbbb6..c26bf83f44ca 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -1165,15 +1165,6 @@ int arm_dma_supported(struct device *dev, u64 mask)
>   	return __dma_supported(dev, mask, false);
>   }
>   
> -#define PREALLOC_DMA_DEBUG_ENTRIES	4096
> -
> -static int __init dma_debug_do_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -core_initcall(dma_debug_do_init);
> -
>   #ifdef CONFIG_ARM_DMA_USE_IOMMU
>   
>   static int __dma_info_to_prot(enum dma_data_direction dir, unsigned long attrs)
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index a96ec0181818..db01f2709842 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -508,16 +508,6 @@ static int __init arm64_dma_init(void)
>   }
>   arch_initcall(arm64_dma_init);
>   
> -#define PREALLOC_DMA_DEBUG_ENTRIES	4096
> -
> -static int __init dma_debug_do_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -fs_initcall(dma_debug_do_init);
> -
> -
>   #ifdef CONFIG_IOMMU_DMA
>   #include <linux/dma-iommu.h>
>   #include <linux/platform_device.h>
> diff --git a/arch/c6x/kernel/dma.c b/arch/c6x/kernel/dma.c
> index 9fff8be75f58..31e1a9ec3a9c 100644
> --- a/arch/c6x/kernel/dma.c
> +++ b/arch/c6x/kernel/dma.c
> @@ -136,14 +136,3 @@ const struct dma_map_ops c6x_dma_ops = {
>   	.sync_sg_for_cpu	= c6x_dma_sync_sg_for_cpu,
>   };
>   EXPORT_SYMBOL(c6x_dma_ops);
> -
> -/* Number of entries preallocated for DMA-API debugging */
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
> -static int __init dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -
> -	return 0;
> -}
> -fs_initcall(dma_init);
> diff --git a/arch/ia64/kernel/dma-mapping.c b/arch/ia64/kernel/dma-mapping.c
> index f2d57e66fd86..7a471d8d67d4 100644
> --- a/arch/ia64/kernel/dma-mapping.c
> +++ b/arch/ia64/kernel/dma-mapping.c
> @@ -9,16 +9,6 @@ int iommu_detected __read_mostly;
>   const struct dma_map_ops *dma_ops;
>   EXPORT_SYMBOL(dma_ops);
>   
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
> -static int __init dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -
> -	return 0;
> -}
> -fs_initcall(dma_init);
> -
>   const struct dma_map_ops *dma_get_ops(struct device *dev)
>   {
>   	return dma_ops;
> diff --git a/arch/microblaze/kernel/dma.c b/arch/microblaze/kernel/dma.c
> index c91e8cef98dd..3145e7dc8ab1 100644
> --- a/arch/microblaze/kernel/dma.c
> +++ b/arch/microblaze/kernel/dma.c
> @@ -184,14 +184,3 @@ const struct dma_map_ops dma_nommu_ops = {
>   	.sync_sg_for_device	= dma_nommu_sync_sg_for_device,
>   };
>   EXPORT_SYMBOL(dma_nommu_ops);
> -
> -/* Number of entries preallocated for DMA-API debugging */
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
> -static int __init dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -
> -	return 0;
> -}
> -fs_initcall(dma_init);
> diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
> index dcafa43613b6..f9fef0028ca2 100644
> --- a/arch/mips/mm/dma-default.c
> +++ b/arch/mips/mm/dma-default.c
> @@ -402,13 +402,3 @@ static const struct dma_map_ops mips_default_dma_map_ops = {
>   
>   const struct dma_map_ops *mips_dma_map_ops = &mips_default_dma_map_ops;
>   EXPORT_SYMBOL(mips_dma_map_ops);
> -
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
> -static int __init mips_dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -
> -	return 0;
> -}
> -fs_initcall(mips_dma_init);
> diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c
> index a945f00011b4..ec7fd45704d2 100644
> --- a/arch/openrisc/kernel/dma.c
> +++ b/arch/openrisc/kernel/dma.c
> @@ -247,14 +247,3 @@ const struct dma_map_ops or1k_dma_map_ops = {
>   	.sync_single_for_device = or1k_sync_single_for_device,
>   };
>   EXPORT_SYMBOL(or1k_dma_map_ops);
> -
> -/* Number of entries preallocated for DMA-API debugging */
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
> -static int __init dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -
> -	return 0;
> -}
> -fs_initcall(dma_init);
> diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
> index da20569de9d4..138157deeadf 100644
> --- a/arch/powerpc/kernel/dma.c
> +++ b/arch/powerpc/kernel/dma.c
> @@ -309,8 +309,6 @@ int dma_set_coherent_mask(struct device *dev, u64 mask)
>   }
>   EXPORT_SYMBOL(dma_set_coherent_mask);
>   
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
>   int dma_set_mask(struct device *dev, u64 dma_mask)
>   {
>   	if (ppc_md.dma_set_mask)
> @@ -361,7 +359,6 @@ EXPORT_SYMBOL_GPL(dma_get_required_mask);
>   
>   static int __init dma_init(void)
>   {
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
>   #ifdef CONFIG_PCI
>   	dma_debug_add_bus(&pci_bus_type);
>   #endif
> diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
> index 2d15d84c20ed..5dee7a922589 100644
> --- a/arch/s390/pci/pci_dma.c
> +++ b/arch/s390/pci/pci_dma.c
> @@ -668,15 +668,6 @@ void zpci_dma_exit(void)
>   	kmem_cache_destroy(dma_region_table_cache);
>   }
>   
> -#define PREALLOC_DMA_DEBUG_ENTRIES	(1 << 16)
> -
> -static int __init dma_debug_do_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -fs_initcall(dma_debug_do_init);
> -
>   const struct dma_map_ops s390_pci_dma_ops = {
>   	.alloc		= s390_dma_alloc,
>   	.free		= s390_dma_free,
> diff --git a/arch/sh/mm/consistent.c b/arch/sh/mm/consistent.c
> index 8ce98691d822..35ea3099a3b6 100644
> --- a/arch/sh/mm/consistent.c
> +++ b/arch/sh/mm/consistent.c
> @@ -20,18 +20,9 @@
>   #include <asm/cacheflush.h>
>   #include <asm/addrspace.h>
>   
> -#define PREALLOC_DMA_DEBUG_ENTRIES	4096
> -
>   const struct dma_map_ops *dma_ops;
>   EXPORT_SYMBOL(dma_ops);
>   
> -static int __init dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -fs_initcall(dma_init);
> -
>   void *dma_generic_alloc_coherent(struct device *dev, size_t size,
>   				 dma_addr_t *dma_handle, gfp_t gfp,
>   				 unsigned long attrs)
> diff --git a/arch/sparc/kernel/Makefile b/arch/sparc/kernel/Makefile
> index 76cb57750dda..84cfc5a428d6 100644
> --- a/arch/sparc/kernel/Makefile
> +++ b/arch/sparc/kernel/Makefile
> @@ -74,8 +74,6 @@ obj-$(CONFIG_SPARC64)	+= pcr.o
>   obj-$(CONFIG_SPARC64)	+= nmi.o
>   obj-$(CONFIG_SPARC64_SMP) += cpumap.o
>   
> -obj-y                     += dma.o
> -
>   obj-$(CONFIG_PCIC_PCI)    += pcic.o
>   obj-$(CONFIG_LEON_PCI)    += leon_pci.o
>   obj-$(CONFIG_SPARC_GRPCI2)+= leon_pci_grpci2.o
> diff --git a/arch/sparc/kernel/dma.c b/arch/sparc/kernel/dma.c
> deleted file mode 100644
> index f73e7597c971..000000000000
> --- a/arch/sparc/kernel/dma.c
> +++ /dev/null
> @@ -1,13 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -#include <linux/kernel.h>
> -#include <linux/dma-mapping.h>
> -#include <linux/dma-debug.h>
> -
> -#define PREALLOC_DMA_DEBUG_ENTRIES       (1 << 15)
> -
> -static int __init dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -fs_initcall(dma_init);
> diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
> index 77625b60a510..bcbaa2e8031e 100644
> --- a/arch/x86/kernel/pci-dma.c
> +++ b/arch/x86/kernel/pci-dma.c
> @@ -55,9 +55,6 @@ struct device x86_dma_fallback_dev = {
>   };
>   EXPORT_SYMBOL(x86_dma_fallback_dev);
>   
> -/* Number of entries preallocated for DMA-API debugging */
> -#define PREALLOC_DMA_DEBUG_ENTRIES       65536
> -
>   void __init pci_iommu_alloc(void)
>   {
>   	struct iommu_table_entry *p;
> @@ -189,7 +186,6 @@ EXPORT_SYMBOL(arch_dma_supported);
>   static int __init pci_iommu_init(void)
>   {
>   	struct iommu_table_entry *p;
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
>   
>   #ifdef CONFIG_PCI
>   	dma_debug_add_bus(&pci_bus_type);
> diff --git a/arch/xtensa/kernel/pci-dma.c b/arch/xtensa/kernel/pci-dma.c
> index 732631ce250f..392b4a80ebc2 100644
> --- a/arch/xtensa/kernel/pci-dma.c
> +++ b/arch/xtensa/kernel/pci-dma.c
> @@ -261,12 +261,3 @@ const struct dma_map_ops xtensa_dma_map_ops = {
>   	.mapping_error = xtensa_dma_mapping_error,
>   };
>   EXPORT_SYMBOL(xtensa_dma_map_ops);
> -
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
> -static int __init xtensa_dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -fs_initcall(xtensa_dma_init);
> diff --git a/include/linux/dma-debug.h b/include/linux/dma-debug.h
> index c7d844f09c3a..a785f2507159 100644
> --- a/include/linux/dma-debug.h
> +++ b/include/linux/dma-debug.h
> @@ -30,8 +30,6 @@ struct bus_type;
>   
>   extern void dma_debug_add_bus(struct bus_type *bus);
>   
> -extern void dma_debug_init(u32 num_entries);
> -
>   extern int dma_debug_resize_entries(u32 num_entries);
>   
>   extern void debug_dma_map_page(struct device *dev, struct page *page,
> @@ -100,10 +98,6 @@ static inline void dma_debug_add_bus(struct bus_type *bus)
>   {
>   }
>   
> -static inline void dma_debug_init(u32 num_entries)
> -{
> -}
> -
>   static inline int dma_debug_resize_entries(u32 num_entries)
>   {
>   	return 0;
> diff --git a/lib/dma-debug.c b/lib/dma-debug.c
> index 7f5cdc1e6b29..712a897174e4 100644
> --- a/lib/dma-debug.c
> +++ b/lib/dma-debug.c
> @@ -41,6 +41,11 @@
>   #define HASH_FN_SHIFT   13
>   #define HASH_FN_MASK    (HASH_SIZE - 1)
>   
> +/* allow architectures to override this if absolutely required */
> +#ifndef PREALLOC_DMA_DEBUG_ENTRIES
> +#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> +#endif
> +
>   enum {
>   	dma_debug_single,
>   	dma_debug_page,
> @@ -1004,18 +1009,16 @@ void dma_debug_add_bus(struct bus_type *bus)
>   	bus_register_notifier(bus, nb);
>   }
>   
> -/*
> - * Let the architectures decide how many entries should be preallocated.
> - */
> -void dma_debug_init(u32 num_entries)
> +static int dma_debug_init(void)
>   {
> +	u32 num_entries;
>   	int i;
>   
>   	/* Do not use dma_debug_initialized here, since we really want to be
>   	 * called to set dma_debug_initialized
>   	 */
>   	if (global_disable)
> -		return;
> +		return 0;
>   
>   	for (i = 0; i < HASH_SIZE; ++i) {
>   		INIT_LIST_HEAD(&dma_entry_hash[i].list);
> @@ -1026,17 +1029,19 @@ void dma_debug_init(u32 num_entries)
>   		pr_err("DMA-API: error creating debugfs entries - disabling\n");
>   		global_disable = true;
>   
> -		return;
> +		return 0;
>   	}
>   
>   	if (req_entries)
>   		num_entries = req_entries;
> +	else
> +		num_entries = PREALLOC_DMA_DEBUG_ENTRIES;
>   
>   	if (prealloc_memory(num_entries) != 0) {
>   		pr_err("DMA-API: debugging out of memory error - disabled\n");
>   		global_disable = true;
>   
> -		return;
> +		return 0;
>   	}
>   
>   	nr_total_entries = num_free_entries;
> @@ -1044,7 +1049,9 @@ void dma_debug_init(u32 num_entries)
>   	dma_debug_initialized = true;
>   
>   	pr_info("DMA-API: debugging enabled by kernel config\n");
> +	return 0;
>   }
> +core_initcall(dma_debug_init);
>   
>   static __init int dma_debug_cmdline(char *str)
>   {
> 

Re: [PATCH 2/3] dma-debug: simplify counting of preallocated requests

[Robin Murphy]

On 24/04/18 15:02, Christoph Hellwig wrote:
> Just keep a single variable with a descriptive name instead of two
> with confusing names.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   lib/dma-debug.c | 20 ++++----------------
>   1 file changed, 4 insertions(+), 16 deletions(-)
> 
> diff --git a/lib/dma-debug.c b/lib/dma-debug.c
> index 712a897174e4..075253cb613b 100644
> --- a/lib/dma-debug.c
> +++ b/lib/dma-debug.c
> @@ -132,7 +132,7 @@ static u32 min_free_entries;
>   static u32 nr_total_entries;
>   
>   /* number of preallocated entries requested by kernel cmdline */
> -static u32 req_entries;
> +static u32 nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
>   
>   /* debugfs dentry's for the stuff above */
>   static struct dentry *dma_debug_dent        __read_mostly;
> @@ -1011,7 +1011,6 @@ void dma_debug_add_bus(struct bus_type *bus)
>   
>   static int dma_debug_init(void)
>   {
> -	u32 num_entries;
>   	int i;
>   
>   	/* Do not use dma_debug_initialized here, since we really want to be
> @@ -1032,12 +1031,7 @@ static int dma_debug_init(void)
>   		return 0;
>   	}
>   
> -	if (req_entries)
> -		num_entries = req_entries;
> -	else
> -		num_entries = PREALLOC_DMA_DEBUG_ENTRIES;
> -
> -	if (prealloc_memory(num_entries) != 0) {
> +	if (prealloc_memory(nr_prealloc_entries) != 0) {
>   		pr_err("DMA-API: debugging out of memory error - disabled\n");
>   		global_disable = true;
>   
> @@ -1068,16 +1062,10 @@ static __init int dma_debug_cmdline(char *str)
>   
>   static __init int dma_debug_entries_cmdline(char *str)
>   {
> -	int res;
> -
>   	if (!str)
>   		return -EINVAL;
> -
> -	res = get_option(&str, &req_entries);
> -
> -	if (!res)
> -		req_entries = 0;
> -
> +	if (!get_option(&str, &nr_prealloc_entries))
> +		nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
>   	return 0;
>   }
>   
> 

Re: [PATCH 4/3] dma-debug: remove CONFIG_HAVE_DMA_API_DEBUG

[Robin Murphy]

On 27/04/18 16:53, Christoph Hellwig wrote:
> There is no arch specific code required for dma-debug, so there is no
> need to opt into the support either.

Makes sense, and a purely negative diffstat is always pleasing :)

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   .../io/dma-api-debug/arch-support.txt         | 31 -------------------
>   arch/Kconfig                                  |  3 --
>   arch/arm/Kconfig                              |  1 -
>   arch/arm64/Kconfig                            |  1 -
>   arch/c6x/Kconfig                              |  1 -
>   arch/ia64/Kconfig                             |  1 -
>   arch/microblaze/Kconfig                       |  1 -
>   arch/mips/Kconfig                             |  1 -
>   arch/powerpc/Kconfig                          |  1 -
>   arch/riscv/Kconfig                            |  1 -
>   arch/s390/Kconfig                             |  1 -
>   arch/sh/Kconfig                               |  1 -
>   arch/sparc/Kconfig                            |  1 -
>   arch/x86/Kconfig                              |  1 -
>   arch/xtensa/Kconfig                           |  1 -
>   lib/Kconfig.debug                             |  1 -
>   16 files changed, 48 deletions(-)
>   delete mode 100644 Documentation/features/io/dma-api-debug/arch-support.txt
> 
> diff --git a/Documentation/features/io/dma-api-debug/arch-support.txt b/Documentation/features/io/dma-api-debug/arch-support.txt
> deleted file mode 100644
> index e438ed675623..000000000000
> --- a/Documentation/features/io/dma-api-debug/arch-support.txt
> +++ /dev/null
> @@ -1,31 +0,0 @@
> -#
> -# Feature name:          dma-api-debug
> -#         Kconfig:       HAVE_DMA_API_DEBUG
> -#         description:   arch supports DMA debug facilities
> -#
> -    -----------------------
> -    |         arch |status|
> -    -----------------------
> -    |       alpha: | TODO |
> -    |         arc: | TODO |
> -    |         arm: |  ok  |
> -    |       arm64: |  ok  |
> -    |         c6x: |  ok  |
> -    |       h8300: | TODO |
> -    |     hexagon: | TODO |
> -    |        ia64: |  ok  |
> -    |        m68k: | TODO |
> -    |  microblaze: |  ok  |
> -    |        mips: |  ok  |
> -    |       nios2: | TODO |
> -    |    openrisc: | TODO |
> -    |      parisc: | TODO |
> -    |     powerpc: |  ok  |
> -    |        s390: |  ok  |
> -    |          sh: |  ok  |
> -    |       sparc: |  ok  |
> -    |          um: | TODO |
> -    |   unicore32: | TODO |
> -    |         x86: |  ok  |
> -    |      xtensa: |  ok  |
> -    -----------------------
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 8e0d665c8d53..f07a1a99e5db 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -278,9 +278,6 @@ config HAVE_CLK
>   	  The <linux/clk.h> calls support software clock gating and
>   	  thus are a key power management tool on many systems.
>   
> -config HAVE_DMA_API_DEBUG
> -	bool
> -
>   config HAVE_HW_BREAKPOINT
>   	bool
>   	depends on PERF_EVENTS
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 676977bdfe33..c43f5bb55ac8 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -60,7 +60,6 @@ config ARM
>   	select HAVE_CONTEXT_TRACKING
>   	select HAVE_C_RECORDMCOUNT
>   	select HAVE_DEBUG_KMEMLEAK
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_DMA_CONTIGUOUS if MMU
>   	select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL) && !CPU_ENDIAN_BE32 && MMU
>   	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index db51b6445744..b25ed7834f6c 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -105,7 +105,6 @@ config ARM64
>   	select HAVE_CONTEXT_TRACKING
>   	select HAVE_DEBUG_BUGVERBOSE
>   	select HAVE_DEBUG_KMEMLEAK
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_DMA_CONTIGUOUS
>   	select HAVE_DYNAMIC_FTRACE
>   	select HAVE_EFFICIENT_UNALIGNED_ACCESS
> diff --git a/arch/c6x/Kconfig b/arch/c6x/Kconfig
> index c6b4dd1418b4..8c088b96e372 100644
> --- a/arch/c6x/Kconfig
> +++ b/arch/c6x/Kconfig
> @@ -10,7 +10,6 @@ config C6X
>   	select GENERIC_ATOMIC64
>   	select GENERIC_IRQ_SHOW
>   	select HAVE_ARCH_TRACEHOOK
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_MEMBLOCK
>   	select SPARSE_IRQ
>   	select IRQ_DOMAIN
> diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
> index 9485b5490eca..2067289fad4a 100644
> --- a/arch/ia64/Kconfig
> +++ b/arch/ia64/Kconfig
> @@ -29,7 +29,6 @@ config IA64
>   	select HAVE_FUNCTION_TRACER
>   	select TTY
>   	select HAVE_ARCH_TRACEHOOK
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_MEMBLOCK
>   	select HAVE_MEMBLOCK_NODE_MAP
>   	select HAVE_VIRT_CPU_ACCOUNTING
> diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
> index 3817a3e2146c..d14782100088 100644
> --- a/arch/microblaze/Kconfig
> +++ b/arch/microblaze/Kconfig
> @@ -19,7 +19,6 @@ config MICROBLAZE
>   	select HAVE_ARCH_HASH
>   	select HAVE_ARCH_KGDB
>   	select HAVE_DEBUG_KMEMLEAK
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_DYNAMIC_FTRACE
>   	select HAVE_FTRACE_MCOUNT_RECORD
>   	select HAVE_FUNCTION_GRAPH_TRACER
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 0f619b8c0e9e..2dcdc13cd65d 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -42,7 +42,6 @@ config MIPS
>   	select HAVE_C_RECORDMCOUNT
>   	select HAVE_DEBUG_KMEMLEAK
>   	select HAVE_DEBUG_STACKOVERFLOW
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_DMA_CONTIGUOUS
>   	select HAVE_DYNAMIC_FTRACE
>   	select HAVE_EXIT_THREAD
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 1887f8f86a77..268fd46fc3c7 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -181,7 +181,6 @@ config PPC
>   	select HAVE_CONTEXT_TRACKING		if PPC64
>   	select HAVE_DEBUG_KMEMLEAK
>   	select HAVE_DEBUG_STACKOVERFLOW
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_DYNAMIC_FTRACE
>   	select HAVE_DYNAMIC_FTRACE_WITH_REGS	if MPROFILE_KERNEL
>   	select HAVE_EBPF_JIT			if PPC64
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 17212ba54ee3..95e2da34aaad 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -23,7 +23,6 @@ config RISCV
>   	select GENERIC_ATOMIC64 if !64BIT || !RISCV_ISA_A
>   	select HAVE_MEMBLOCK
>   	select HAVE_MEMBLOCK_NODE_MAP
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_DMA_CONTIGUOUS
>   	select HAVE_GENERIC_DMA_COHERENT
>   	select IRQ_DOMAIN
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index b794a2ab6d15..6a64287ec1da 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -130,7 +130,6 @@ config S390
>   	select HAVE_CMPXCHG_LOCAL
>   	select HAVE_COPY_THREAD_TLS
>   	select HAVE_DEBUG_KMEMLEAK
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_DMA_CONTIGUOUS
>   	select DMA_DIRECT_OPS
>   	select HAVE_DYNAMIC_FTRACE
> diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
> index 9417f70e008e..7d521926041e 100644
> --- a/arch/sh/Kconfig
> +++ b/arch/sh/Kconfig
> @@ -13,7 +13,6 @@ config SUPERH
>   	select HAVE_OPROFILE
>   	select HAVE_GENERIC_DMA_COHERENT
>   	select HAVE_ARCH_TRACEHOOK
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_PERF_EVENTS
>   	select HAVE_DEBUG_BUGVERBOSE
>   	select ARCH_HAVE_CUSTOM_GPIO_H
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index c1cfc17eb504..435dbc033afe 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -25,7 +25,6 @@ config SPARC
>   	select RTC_CLASS
>   	select RTC_DRV_M48T59
>   	select RTC_SYSTOHC
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_ARCH_JUMP_LABEL if SPARC64
>   	select GENERIC_IRQ_SHOW
>   	select ARCH_WANT_IPC_PARSE_VERSION
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index aad35c568681..3eeca48a146b 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -135,7 +135,6 @@ config X86
>   	select HAVE_C_RECORDMCOUNT
>   	select HAVE_DEBUG_KMEMLEAK
>   	select HAVE_DEBUG_STACKOVERFLOW
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_DMA_CONTIGUOUS
>   	select HAVE_DYNAMIC_FTRACE
>   	select HAVE_DYNAMIC_FTRACE_WITH_REGS
> diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
> index c921e8bccdc8..17df332269b2 100644
> --- a/arch/xtensa/Kconfig
> +++ b/arch/xtensa/Kconfig
> @@ -19,7 +19,6 @@ config XTENSA
>   	select HAVE_ARCH_KASAN if MMU
>   	select HAVE_CC_STACKPROTECTOR
>   	select HAVE_DEBUG_KMEMLEAK
> -	select HAVE_DMA_API_DEBUG
>   	select HAVE_DMA_CONTIGUOUS
>   	select HAVE_EXIT_THREAD
>   	select HAVE_FUNCTION_TRACER
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 685ed2dd4384..d5175eb7b917 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -1634,7 +1634,6 @@ config PROVIDE_OHCI1394_DMA_INIT
>   
>   config DMA_API_DEBUG
>   	bool "Enable debugging of DMA-API usage"
> -	depends on HAVE_DMA_API_DEBUG
>   	select NEED_DMA_MAP_STATE
>   	help
>   	  Enable this option to debug the use of the DMA API by device drivers.
> 

Re: [PATCH 3/3] dma-debug: unexport dma_debug_resize_entries and debug_dma_dump_mappings

[Robin Murphy]

On 24/04/18 15:02, Christoph Hellwig wrote:
> Only used by the AMD GART driver, which must be built in.

FWIW debug_dma_dump_mappings() is also called by the Intel VT-d driver, 
but the same reasoning still applies. This does rather beg the question 
of whether it's right to have bits of low-level dma-debug internals 
*only* called by a couple of IOMMU drivers, but that can wait for 
another day.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   lib/dma-debug.c | 2 --
>   1 file changed, 2 deletions(-)
> 
> diff --git a/lib/dma-debug.c b/lib/dma-debug.c
> index 075253cb613b..6a1ebaa83623 100644
> --- a/lib/dma-debug.c
> +++ b/lib/dma-debug.c
> @@ -444,7 +444,6 @@ void debug_dma_dump_mappings(struct device *dev)
>   		spin_unlock_irqrestore(&bucket->lock, flags);
>   	}
>   }
> -EXPORT_SYMBOL(debug_dma_dump_mappings);
>   
>   /*
>    * For each mapping (initial cacheline in the case of
> @@ -753,7 +752,6 @@ int dma_debug_resize_entries(u32 num_entries)
>   
>   	return ret;
>   }
> -EXPORT_SYMBOL(dma_debug_resize_entries);
>   
>   /*
>    * DMA-API debugging init code
> 

Re: [PATCH 1/3] dma-debug: move initialization to common code

[Marek Szyprowski]

Hi Christoph,

On 2018-04-24 16:02, Christoph Hellwig wrote:
> Most mainstream architectures are using 65536 entries, so lets stick to
> that.  If someone is really desperate to override it that can still be
> done through <asm/dma-mapping.h>, but I'd rather see a really good
> rationale for that.
>
> dma_debug_init is now called as a core_initcall, which for many
> architectures means much earlier, and provides dma-debug functionality
> earlier in the boot process.  This should be safe as it only relies
> on the memory allocator already being available.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Nice! Unification of this is definitely needed and solves the issues
reported some time ago:

https://patchwork.kernel.org/patch/9429637/ (arm)
https://patchwork.kernel.org/patch/9431161/ (arm64, rejected)

Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---
>   arch/arm/mm/dma-mapping-nommu.c |  9 ---------
>   arch/arm/mm/dma-mapping.c       |  9 ---------
>   arch/arm64/mm/dma-mapping.c     | 10 ----------
>   arch/c6x/kernel/dma.c           | 11 -----------
>   arch/ia64/kernel/dma-mapping.c  | 10 ----------
>   arch/microblaze/kernel/dma.c    | 11 -----------
>   arch/mips/mm/dma-default.c      | 10 ----------
>   arch/openrisc/kernel/dma.c      | 11 -----------
>   arch/powerpc/kernel/dma.c       |  3 ---
>   arch/s390/pci/pci_dma.c         |  9 ---------
>   arch/sh/mm/consistent.c         |  9 ---------
>   arch/sparc/kernel/Makefile      |  2 --
>   arch/sparc/kernel/dma.c         | 13 -------------
>   arch/x86/kernel/pci-dma.c       |  4 ----
>   arch/xtensa/kernel/pci-dma.c    |  9 ---------
>   include/linux/dma-debug.h       |  6 ------
>   lib/dma-debug.c                 | 21 ++++++++++++++-------
>   17 files changed, 14 insertions(+), 143 deletions(-)
>   delete mode 100644 arch/sparc/kernel/dma.c
>
> diff --git a/arch/arm/mm/dma-mapping-nommu.c b/arch/arm/mm/dma-mapping-nommu.c
> index 619f24a42d09..f448a0663b10 100644
> --- a/arch/arm/mm/dma-mapping-nommu.c
> +++ b/arch/arm/mm/dma-mapping-nommu.c
> @@ -241,12 +241,3 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
>   void arch_teardown_dma_ops(struct device *dev)
>   {
>   }
> -
> -#define PREALLOC_DMA_DEBUG_ENTRIES	4096
> -
> -static int __init dma_debug_do_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -core_initcall(dma_debug_do_init);
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index 8c398fedbbb6..c26bf83f44ca 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -1165,15 +1165,6 @@ int arm_dma_supported(struct device *dev, u64 mask)
>   	return __dma_supported(dev, mask, false);
>   }
>   
> -#define PREALLOC_DMA_DEBUG_ENTRIES	4096
> -
> -static int __init dma_debug_do_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -core_initcall(dma_debug_do_init);
> -
>   #ifdef CONFIG_ARM_DMA_USE_IOMMU
>   
>   static int __dma_info_to_prot(enum dma_data_direction dir, unsigned long attrs)
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index a96ec0181818..db01f2709842 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -508,16 +508,6 @@ static int __init arm64_dma_init(void)
>   }
>   arch_initcall(arm64_dma_init);
>   
> -#define PREALLOC_DMA_DEBUG_ENTRIES	4096
> -
> -static int __init dma_debug_do_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -fs_initcall(dma_debug_do_init);
> -
> -
>   #ifdef CONFIG_IOMMU_DMA
>   #include <linux/dma-iommu.h>
>   #include <linux/platform_device.h>
> diff --git a/arch/c6x/kernel/dma.c b/arch/c6x/kernel/dma.c
> index 9fff8be75f58..31e1a9ec3a9c 100644
> --- a/arch/c6x/kernel/dma.c
> +++ b/arch/c6x/kernel/dma.c
> @@ -136,14 +136,3 @@ const struct dma_map_ops c6x_dma_ops = {
>   	.sync_sg_for_cpu	= c6x_dma_sync_sg_for_cpu,
>   };
>   EXPORT_SYMBOL(c6x_dma_ops);
> -
> -/* Number of entries preallocated for DMA-API debugging */
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
> -static int __init dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -
> -	return 0;
> -}
> -fs_initcall(dma_init);
> diff --git a/arch/ia64/kernel/dma-mapping.c b/arch/ia64/kernel/dma-mapping.c
> index f2d57e66fd86..7a471d8d67d4 100644
> --- a/arch/ia64/kernel/dma-mapping.c
> +++ b/arch/ia64/kernel/dma-mapping.c
> @@ -9,16 +9,6 @@ int iommu_detected __read_mostly;
>   const struct dma_map_ops *dma_ops;
>   EXPORT_SYMBOL(dma_ops);
>   
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
> -static int __init dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -
> -	return 0;
> -}
> -fs_initcall(dma_init);
> -
>   const struct dma_map_ops *dma_get_ops(struct device *dev)
>   {
>   	return dma_ops;
> diff --git a/arch/microblaze/kernel/dma.c b/arch/microblaze/kernel/dma.c
> index c91e8cef98dd..3145e7dc8ab1 100644
> --- a/arch/microblaze/kernel/dma.c
> +++ b/arch/microblaze/kernel/dma.c
> @@ -184,14 +184,3 @@ const struct dma_map_ops dma_nommu_ops = {
>   	.sync_sg_for_device	= dma_nommu_sync_sg_for_device,
>   };
>   EXPORT_SYMBOL(dma_nommu_ops);
> -
> -/* Number of entries preallocated for DMA-API debugging */
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
> -static int __init dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -
> -	return 0;
> -}
> -fs_initcall(dma_init);
> diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
> index dcafa43613b6..f9fef0028ca2 100644
> --- a/arch/mips/mm/dma-default.c
> +++ b/arch/mips/mm/dma-default.c
> @@ -402,13 +402,3 @@ static const struct dma_map_ops mips_default_dma_map_ops = {
>   
>   const struct dma_map_ops *mips_dma_map_ops = &mips_default_dma_map_ops;
>   EXPORT_SYMBOL(mips_dma_map_ops);
> -
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
> -static int __init mips_dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -
> -	return 0;
> -}
> -fs_initcall(mips_dma_init);
> diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c
> index a945f00011b4..ec7fd45704d2 100644
> --- a/arch/openrisc/kernel/dma.c
> +++ b/arch/openrisc/kernel/dma.c
> @@ -247,14 +247,3 @@ const struct dma_map_ops or1k_dma_map_ops = {
>   	.sync_single_for_device = or1k_sync_single_for_device,
>   };
>   EXPORT_SYMBOL(or1k_dma_map_ops);
> -
> -/* Number of entries preallocated for DMA-API debugging */
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
> -static int __init dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -
> -	return 0;
> -}
> -fs_initcall(dma_init);
> diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
> index da20569de9d4..138157deeadf 100644
> --- a/arch/powerpc/kernel/dma.c
> +++ b/arch/powerpc/kernel/dma.c
> @@ -309,8 +309,6 @@ int dma_set_coherent_mask(struct device *dev, u64 mask)
>   }
>   EXPORT_SYMBOL(dma_set_coherent_mask);
>   
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
>   int dma_set_mask(struct device *dev, u64 dma_mask)
>   {
>   	if (ppc_md.dma_set_mask)
> @@ -361,7 +359,6 @@ EXPORT_SYMBOL_GPL(dma_get_required_mask);
>   
>   static int __init dma_init(void)
>   {
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
>   #ifdef CONFIG_PCI
>   	dma_debug_add_bus(&pci_bus_type);
>   #endif
> diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
> index 2d15d84c20ed..5dee7a922589 100644
> --- a/arch/s390/pci/pci_dma.c
> +++ b/arch/s390/pci/pci_dma.c
> @@ -668,15 +668,6 @@ void zpci_dma_exit(void)
>   	kmem_cache_destroy(dma_region_table_cache);
>   }
>   
> -#define PREALLOC_DMA_DEBUG_ENTRIES	(1 << 16)
> -
> -static int __init dma_debug_do_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -fs_initcall(dma_debug_do_init);
> -
>   const struct dma_map_ops s390_pci_dma_ops = {
>   	.alloc		= s390_dma_alloc,
>   	.free		= s390_dma_free,
> diff --git a/arch/sh/mm/consistent.c b/arch/sh/mm/consistent.c
> index 8ce98691d822..35ea3099a3b6 100644
> --- a/arch/sh/mm/consistent.c
> +++ b/arch/sh/mm/consistent.c
> @@ -20,18 +20,9 @@
>   #include <asm/cacheflush.h>
>   #include <asm/addrspace.h>
>   
> -#define PREALLOC_DMA_DEBUG_ENTRIES	4096
> -
>   const struct dma_map_ops *dma_ops;
>   EXPORT_SYMBOL(dma_ops);
>   
> -static int __init dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -fs_initcall(dma_init);
> -
>   void *dma_generic_alloc_coherent(struct device *dev, size_t size,
>   				 dma_addr_t *dma_handle, gfp_t gfp,
>   				 unsigned long attrs)
> diff --git a/arch/sparc/kernel/Makefile b/arch/sparc/kernel/Makefile
> index 76cb57750dda..84cfc5a428d6 100644
> --- a/arch/sparc/kernel/Makefile
> +++ b/arch/sparc/kernel/Makefile
> @@ -74,8 +74,6 @@ obj-$(CONFIG_SPARC64)	+= pcr.o
>   obj-$(CONFIG_SPARC64)	+= nmi.o
>   obj-$(CONFIG_SPARC64_SMP) += cpumap.o
>   
> -obj-y                     += dma.o
> -
>   obj-$(CONFIG_PCIC_PCI)    += pcic.o
>   obj-$(CONFIG_LEON_PCI)    += leon_pci.o
>   obj-$(CONFIG_SPARC_GRPCI2)+= leon_pci_grpci2.o
> diff --git a/arch/sparc/kernel/dma.c b/arch/sparc/kernel/dma.c
> deleted file mode 100644
> index f73e7597c971..000000000000
> --- a/arch/sparc/kernel/dma.c
> +++ /dev/null
> @@ -1,13 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -#include <linux/kernel.h>
> -#include <linux/dma-mapping.h>
> -#include <linux/dma-debug.h>
> -
> -#define PREALLOC_DMA_DEBUG_ENTRIES       (1 << 15)
> -
> -static int __init dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -fs_initcall(dma_init);
> diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
> index 77625b60a510..bcbaa2e8031e 100644
> --- a/arch/x86/kernel/pci-dma.c
> +++ b/arch/x86/kernel/pci-dma.c
> @@ -55,9 +55,6 @@ struct device x86_dma_fallback_dev = {
>   };
>   EXPORT_SYMBOL(x86_dma_fallback_dev);
>   
> -/* Number of entries preallocated for DMA-API debugging */
> -#define PREALLOC_DMA_DEBUG_ENTRIES       65536
> -
>   void __init pci_iommu_alloc(void)
>   {
>   	struct iommu_table_entry *p;
> @@ -189,7 +186,6 @@ EXPORT_SYMBOL(arch_dma_supported);
>   static int __init pci_iommu_init(void)
>   {
>   	struct iommu_table_entry *p;
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
>   
>   #ifdef CONFIG_PCI
>   	dma_debug_add_bus(&pci_bus_type);
> diff --git a/arch/xtensa/kernel/pci-dma.c b/arch/xtensa/kernel/pci-dma.c
> index 732631ce250f..392b4a80ebc2 100644
> --- a/arch/xtensa/kernel/pci-dma.c
> +++ b/arch/xtensa/kernel/pci-dma.c
> @@ -261,12 +261,3 @@ const struct dma_map_ops xtensa_dma_map_ops = {
>   	.mapping_error = xtensa_dma_mapping_error,
>   };
>   EXPORT_SYMBOL(xtensa_dma_map_ops);
> -
> -#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> -
> -static int __init xtensa_dma_init(void)
> -{
> -	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
> -	return 0;
> -}
> -fs_initcall(xtensa_dma_init);
> diff --git a/include/linux/dma-debug.h b/include/linux/dma-debug.h
> index c7d844f09c3a..a785f2507159 100644
> --- a/include/linux/dma-debug.h
> +++ b/include/linux/dma-debug.h
> @@ -30,8 +30,6 @@ struct bus_type;
>   
>   extern void dma_debug_add_bus(struct bus_type *bus);
>   
> -extern void dma_debug_init(u32 num_entries);
> -
>   extern int dma_debug_resize_entries(u32 num_entries);
>   
>   extern void debug_dma_map_page(struct device *dev, struct page *page,
> @@ -100,10 +98,6 @@ static inline void dma_debug_add_bus(struct bus_type *bus)
>   {
>   }
>   
> -static inline void dma_debug_init(u32 num_entries)
> -{
> -}
> -
>   static inline int dma_debug_resize_entries(u32 num_entries)
>   {
>   	return 0;
> diff --git a/lib/dma-debug.c b/lib/dma-debug.c
> index 7f5cdc1e6b29..712a897174e4 100644
> --- a/lib/dma-debug.c
> +++ b/lib/dma-debug.c
> @@ -41,6 +41,11 @@
>   #define HASH_FN_SHIFT   13
>   #define HASH_FN_MASK    (HASH_SIZE - 1)
>   
> +/* allow architectures to override this if absolutely required */
> +#ifndef PREALLOC_DMA_DEBUG_ENTRIES
> +#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
> +#endif
> +
>   enum {
>   	dma_debug_single,
>   	dma_debug_page,
> @@ -1004,18 +1009,16 @@ void dma_debug_add_bus(struct bus_type *bus)
>   	bus_register_notifier(bus, nb);
>   }
>   
> -/*
> - * Let the architectures decide how many entries should be preallocated.
> - */
> -void dma_debug_init(u32 num_entries)
> +static int dma_debug_init(void)
>   {
> +	u32 num_entries;
>   	int i;
>   
>   	/* Do not use dma_debug_initialized here, since we really want to be
>   	 * called to set dma_debug_initialized
>   	 */
>   	if (global_disable)
> -		return;
> +		return 0;
>   
>   	for (i = 0; i < HASH_SIZE; ++i) {
>   		INIT_LIST_HEAD(&dma_entry_hash[i].list);
> @@ -1026,17 +1029,19 @@ void dma_debug_init(u32 num_entries)
>   		pr_err("DMA-API: error creating debugfs entries - disabling\n");
>   		global_disable = true;
>   
> -		return;
> +		return 0;
>   	}
>   
>   	if (req_entries)
>   		num_entries = req_entries;
> +	else
> +		num_entries = PREALLOC_DMA_DEBUG_ENTRIES;
>   
>   	if (prealloc_memory(num_entries) != 0) {
>   		pr_err("DMA-API: debugging out of memory error - disabled\n");
>   		global_disable = true;
>   
> -		return;
> +		return 0;
>   	}
>   
>   	nr_total_entries = num_free_entries;
> @@ -1044,7 +1049,9 @@ void dma_debug_init(u32 num_entries)
>   	dma_debug_initialized = true;
>   
>   	pr_info("DMA-API: debugging enabled by kernel config\n");
> +	return 0;
>   }
> +core_initcall(dma_debug_init);
>   
>   static __init int dma_debug_cmdline(char *str)
>   {

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

Re: [PATCH 3/3] dma-debug: unexport dma_debug_resize_entries and debug_dma_dump_mappings

[Christoph Hellwig]

On Tue, May 08, 2018 at 11:05:20AM +0100, Robin Murphy wrote:
> On 24/04/18 15:02, Christoph Hellwig wrote:
>> Only used by the AMD GART driver, which must be built in.
>
> FWIW debug_dma_dump_mappings() is also called by the Intel VT-d driver, but 
> the same reasoning still applies.

I'll update the changelog.

> This does rather beg the question of 
> whether it's right to have bits of low-level dma-debug internals *only* 
> called by a couple of IOMMU drivers, but that can wait for another day.

My gut feeling is that it is wrong, but I didn't have time to look into
the details and history of how this happened.