arch: switch the default on ARCH_HAS_SG_CHAIN
These days architectures are mostly out of the business of dealing with
struct scatterlist at all, unless they have architecture specific iommu
drivers. Replace the ARCH_HAS_SG_CHAIN symbol with a ARCH_NO_SG_CHAIN
one only enabled for architectures with horrible legacy iommu drivers
like alpha and parisc, and conditionally for arm which wants to keep it
disable for legacy platforms.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
diff --git a/Documentation/features/io/sg-chain/arch-support.txt b/Documentation/features/io/sg-chain/arch-support.txt
deleted file mode 100644
index 6554f03..0000000
--- a/Documentation/features/io/sg-chain/arch-support.txt
+++ /dev/null
@@ -1,33 +0,0 @@
-#
-# Feature name: sg-chain
-# Kconfig: ARCH_HAS_SG_CHAIN
-# description: arch supports chained scatter-gather lists
-#
- -----------------------
- | arch |status|
- -----------------------
- | alpha: | TODO |
- | arc: | ok |
- | arm: | ok |
- | arm64: | ok |
- | c6x: | TODO |
- | h8300: | TODO |
- | hexagon: | TODO |
- | ia64: | ok |
- | m68k: | TODO |
- | microblaze: | TODO |
- | mips: | TODO |
- | nds32: | TODO |
- | nios2: | TODO |
- | openrisc: | TODO |
- | parisc: | TODO |
- | powerpc: | ok |
- | riscv: | TODO |
- | s390: | ok |
- | sh: | TODO |
- | sparc: | ok |
- | um: | TODO |
- | unicore32: | TODO |
- | x86: | ok |
- | xtensa: | TODO |
- -----------------------
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 5b4f883..a7e748a 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -5,6 +5,7 @@
select ARCH_MIGHT_HAVE_PC_PARPORT
select ARCH_MIGHT_HAVE_PC_SERIO
select ARCH_NO_PREEMPT
+ select ARCH_NO_SG_CHAIN
select ARCH_USE_CMPXCHG_LOCKREF
select HAVE_AOUT
select HAVE_IDE
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index c9e2a13..fd48d698 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -13,7 +13,6 @@
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_SYNC_DMA_FOR_CPU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
- select ARCH_HAS_SG_CHAIN
select ARCH_SUPPORTS_ATOMIC_RMW if ARC_HAS_LLSC
select BUILDTIME_EXTABLE_SORT
select CLONE_BACKWARDS
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 3b2852d..a858ee7 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -19,6 +19,7 @@
select ARCH_HAVE_CUSTOM_GPIO_H
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_MIGHT_HAVE_PC_PARPORT
+ select ARCH_NO_SG_CHAIN if !ARM_HAS_SG_CHAIN
select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
select ARCH_SUPPORTS_ATOMIC_RMW
@@ -119,7 +120,6 @@
<http://www.arm.linux.org.uk/>.
config ARM_HAS_SG_CHAIN
- select ARCH_HAS_SG_CHAIN
bool
config ARM_DMA_USE_IOMMU
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 2e645ea..06cf0ef 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -23,7 +23,6 @@
select ARCH_HAS_MEMBARRIER_SYNC_CORE
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_SET_MEMORY
- select ARCH_HAS_SG_CHAIN
select ARCH_HAS_STRICT_KERNEL_RWX
select ARCH_HAS_STRICT_MODULE_RWX
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 36773de..d6f2036 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -29,7 +29,6 @@
select HAVE_MEMBLOCK_NODE_MAP
select HAVE_VIRT_CPU_ACCOUNTING
select ARCH_HAS_DMA_MARK_CLEAN
- select ARCH_HAS_SG_CHAIN
select VIRT_TO_BUS
select ARCH_DISCARD_MEMBLOCK
select GENERIC_IRQ_PROBE
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 92a339e..428ee50 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -11,6 +11,7 @@
select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_STRICT_KERNEL_RWX
select ARCH_HAS_UBSAN_SANITIZE_ALL
+ select ARCH_NO_SG_CHAIN
select ARCH_SUPPORTS_MEMORY_FAILURE
select RTC_CLASS
select RTC_DRV_GENERIC
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 8be3126..4bc8edd 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -138,7 +138,6 @@
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_MEMBARRIER_CALLBACKS
select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE && PPC64
- select ARCH_HAS_SG_CHAIN
select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !RELOCATABLE && !HIBERNATION)
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HAS_UACCESS_FLUSHCACHE if PPC64
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 5173366..5624e86 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -73,7 +73,6 @@
select ARCH_HAS_KCOV
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_SET_MEMORY
- select ARCH_HAS_SG_CHAIN
select ARCH_HAS_STRICT_KERNEL_RWX
select ARCH_HAS_STRICT_MODULE_RWX
select ARCH_HAS_UBSAN_SANITIZE_ALL
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 490b2c9..8853b6c 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -40,7 +40,6 @@
select MODULES_USE_ELF_RELA
select ODD_RT_SIGACTION
select OLD_SIGSUSPEND
- select ARCH_HAS_SG_CHAIN
select CPU_NO_EFFICIENT_FFS
select LOCKDEP_SMALL if LOCKDEP
select NEED_DMA_MAP_STATE
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9d734f3..adc845b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -66,7 +66,6 @@
select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
select ARCH_HAS_SET_MEMORY
- select ARCH_HAS_SG_CHAIN
select ARCH_HAS_STRICT_KERNEL_RWX
select ARCH_HAS_STRICT_MODULE_RWX
select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 239bfb1..75488b6 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -1,7 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
config XTENSA
def_bool y
- select ARCH_HAS_SG_CHAIN
select ARCH_HAS_SYNC_DMA_FOR_CPU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
select ARCH_NO_COHERENT_DMA_MMAP if !MMU
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 093aa57..b96f0d0 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -324,10 +324,10 @@ size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
* Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
* is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
*/
-#ifdef CONFIG_ARCH_HAS_SG_CHAIN
-#define SG_MAX_SEGMENTS 2048
-#else
+#ifdef CONFIG_ARCH_NO_SG_CHAIN
#define SG_MAX_SEGMENTS SG_CHUNK_SIZE
+#else
+#define SG_MAX_SEGMENTS 2048
#endif
#ifdef CONFIG_SG_POOL
diff --git a/lib/Kconfig b/lib/Kconfig
index a9965f4..d5a5e2e 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -577,7 +577,7 @@
# sg chaining option
#
-config ARCH_HAS_SG_CHAIN
+config ARCH_NO_SG_CHAIN
def_bool n
config ARCH_HAS_PMEM_API
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 7c6096a..9ba349e 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -271,7 +271,7 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents,
if (nents == 0)
return -EINVAL;
-#ifndef CONFIG_ARCH_HAS_SG_CHAIN
+#ifdef CONFIG_ARCH_NO_SG_CHAIN
if (WARN_ON_ONCE(nents > max_ents))
return -EINVAL;
#endif