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Message-ID: <15333.1417721231@famine>
Date: Thu, 04 Dec 2014 11:27:11 -0800
From: Jay Vosburgh <jay.vosburgh@...onical.com>
To: Hannes Frederic Sowa <hannes@...essinduktion.org>
cc: netdev@...r.kernel.org, Herbert Xu <herbert@...dor.apana.org.au>,
Thomas Graf <tgraf@...g.ch>,
Daniel Borkmann <dborkman@...hat.com>,
Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH net-next] arch_fast_hash: avoid indirect function calls and implement hash in asm
Hannes Frederic Sowa <hannes@...essinduktion.org> wrote:
>By default the arch_fast_hash hashing function pointers are initialized
>to jhash(2). If during boot-up a CPU with SSE4.2 is detected they get
>updated to the CRC32 ones. This dispatching scheme incurs a function
>pointer lookup and indirect call for every hashing operation.
>
>To keep the number of clobbered registers short the hashing primitives
>are implemented in assembler. This makes it easier to do the dispatch
>by alternative_call.
I have tested this on the same system that panicked with the
original (now reverted) implementation (commit e5a2c8999576 "fast_hash:
avoid indirect function calls"), and it functions correctly and does not
panic.
I looked at the disassembly, and, as a data point, on a
non-SSE4.2 system, the code generated is not as efficient as Hannes'
original test patch, found here:
http://comments.gmane.org/gmane.linux.network/338430
which produced code as follows:
0xffffffffa00b6bb9 <ovs_flow_tbl_insert+0xb9>: mov %r15,0x348(%r14)
0xffffffffa00b6bc0 <ovs_flow_tbl_insert+0xc0>: movzwl 0x28(%r15),%ecx
0xffffffffa00b6bc5 <ovs_flow_tbl_insert+0xc5>: movzwl 0x2a(%r15),%esi
0xffffffffa00b6bca <ovs_flow_tbl_insert+0xca>: movzwl %cx,%eax
0xffffffffa00b6bcd <ovs_flow_tbl_insert+0xcd>: sub %ecx,%esi
0xffffffffa00b6bcf <ovs_flow_tbl_insert+0xcf>: lea 0x38(%r14,%rax,1),%rdi
0xffffffffa00b6bd4 <ovs_flow_tbl_insert+0xd4>: sar $0x2,%esi
0xffffffffa00b6bd7 <ovs_flow_tbl_insert+0xd7>: callq 0xffffffff813a7810 <__jhash2>
0xffffffffa00b6bdc <ovs_flow_tbl_insert+0xdc>: mov %eax,0x30(%r14)
0xffffffffa00b6be0 <ovs_flow_tbl_insert+0xe0>: mov (%rbx),%r13
0xffffffffa00b6be3 <ovs_flow_tbl_insert+0xe3>: mov %r14,%rsi
0xffffffffa00b6be6 <ovs_flow_tbl_insert+0xe6>: mov %r13,%rdi
0xffffffffa00b6be9 <ovs_flow_tbl_insert+0xe9>: callq 0xffffffffa00b61a0 <table_instance_insert>
This patch's code ends up as follows:
0xffffffffa01b5a57 <ovs_flow_tbl_insert+0xb7>: mov %r15,0x348(%rcx)
0xffffffffa01b5a5e <ovs_flow_tbl_insert+0xbe>: movzwl 0x28(%r15),%eax
0xffffffffa01b5a63 <ovs_flow_tbl_insert+0xc3>: movzwl 0x2a(%r15),%esi
0xffffffffa01b5a68 <ovs_flow_tbl_insert+0xc8>: movzwl %ax,%edx
0xffffffffa01b5a6b <ovs_flow_tbl_insert+0xcb>: sub %eax,%esi
0xffffffffa01b5a6d <ovs_flow_tbl_insert+0xcd>: lea 0x38(%rcx,%rdx,1),%rdi
0xffffffffa01b5a72 <ovs_flow_tbl_insert+0xd2>: xor %edx,%edx
0xffffffffa01b5a74 <ovs_flow_tbl_insert+0xd4>: sar $0x2,%esi
0xffffffffa01b5a77 <ovs_flow_tbl_insert+0xd7>: callq 0xffffffff813ae9f0 <__jhash_trampoline>
0xffffffffa01b5a7c <ovs_flow_tbl_insert+0xdc>: mov %eax,0x30(%rcx)
0xffffffffa01b5a7f <ovs_flow_tbl_insert+0xdf>: mov (%rbx),%r13
0xffffffffa01b5a82 <ovs_flow_tbl_insert+0xe2>: mov %rcx,%rsi
0xffffffffa01b5a85 <ovs_flow_tbl_insert+0xe5>: mov %r13,%rdi
0xffffffffa01b5a88 <ovs_flow_tbl_insert+0xe8>: callq 0xffffffffa01b5030 <table_instance_insert>
0xffffffff813ae9f0 <__jhash_trampoline>: push %rcx
0xffffffff813ae9f1 <__jhash_trampoline+0x1>: push %r8
0xffffffff813ae9f3 <__jhash_trampoline+0x3>: push %r9
0xffffffff813ae9f5 <__jhash_trampoline+0x5>: push %r10
0xffffffff813ae9f7 <__jhash_trampoline+0x7>: push %r11
0xffffffff813ae9f9 <__jhash_trampoline+0x9>: callq 0xffffffff813ae8a0 <__jhash>
0xffffffff813ae9fe <__jhash_trampoline+0xe>: pop %r11
0xffffffff813aea00 <__jhash_trampoline+0x10>: pop %r10
0xffffffff813aea02 <__jhash_trampoline+0x12>: pop %r9
0xffffffff813aea04 <__jhash_trampoline+0x14>: pop %r8
0xffffffff813aea06 <__jhash_trampoline+0x16>: pop %rcx
0xffffffff813aea07 <__jhash_trampoline+0x17>: retq
In any event, this new patch does work correctly in my test that
originally failed, and it's debatable how much optimizing for old
systems is worthwhile.
I only tested the non-SSE4.2 (i.e., old system) portion on
x86_64.
Tested-by: Jay Vosburgh <jay.vosburgh@...onical.com>
-J
>Cc: Herbert Xu <herbert@...dor.apana.org.au>
>Cc: Jay Vosburgh <jay.vosburgh@...onical.com>
>Cc: Thomas Graf <tgraf@...g.ch>
>Cc: Daniel Borkmann <dborkman@...hat.com>
>Cc: Eric Dumazet <eric.dumazet@...il.com>
>Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
>---
> arch/x86/include/asm/hash.h | 53 ++++++++++-
> arch/x86/kernel/i386_ksyms_32.c | 6 ++
> arch/x86/kernel/x8664_ksyms_64.c | 6 ++
> arch/x86/lib/Makefile | 2 +-
> arch/x86/lib/arch_hash.S | 192 +++++++++++++++++++++++++++++++++++++++
> arch/x86/lib/hash.c | 92 -------------------
> arch/x86/lib/jhash.c | 6 ++
> include/asm-generic/hash.h | 18 +++-
> include/linux/hash.h | 34 -------
> lib/Makefile | 2 +-
> lib/hash.c | 39 --------
> net/openvswitch/flow_table.c | 2 +-
> 12 files changed, 280 insertions(+), 172 deletions(-)
> create mode 100644 arch/x86/lib/arch_hash.S
> delete mode 100644 arch/x86/lib/hash.c
> create mode 100644 arch/x86/lib/jhash.c
> delete mode 100644 lib/hash.c
>
>diff --git a/arch/x86/include/asm/hash.h b/arch/x86/include/asm/hash.h
>index e8c58f8..620081b 100644
>--- a/arch/x86/include/asm/hash.h
>+++ b/arch/x86/include/asm/hash.h
>@@ -1,7 +1,56 @@
> #ifndef _ASM_X86_HASH_H
> #define _ASM_X86_HASH_H
>
>-struct fast_hash_ops;
>-extern void setup_arch_fast_hash(struct fast_hash_ops *ops);
>+#include <linux/cpufeature.h>
>+#include <asm/alternative.h>
>+
>+#include <linux/jhash.h>
>+
>+#ifdef CONFIG_AS_CRC32
>+
>+u32 __jhash_trampoline(const void *data, u32 len, u32 seed);
>+u32 __sse42_crc32(const void *data, u32 len, u32 seed);
>+
>+#ifdef CONFIG_X86_64
>+
>+static inline u32 arch_fast_hash(const void *data, u32 len, u32 seed)
>+{
>+ u32 hash;
>+
>+ alternative_call(__jhash_trampoline, __sse42_crc32, X86_FEATURE_XMM4_2,
>+ ASM_OUTPUT2("=a" (hash), "=D" (data), "=S" (len),
>+ "=d" (seed)),
>+ "1" (data), "2" (len), "3" (seed)
>+ : "memory", "cc");
>+
>+ return hash;
>+}
>+
>+#else /* CONFIG_X86_64 */
>+
>+static inline u32 arch_fast_hash(const void *data, u32 len, u32 seed)
>+{
>+ u32 hash;
>+
>+ alternative_call(__jhash_trampoline, __sse42_crc32, X86_FEATURE_XMM4_2,
>+ ASM_OUTPUT2("=a" (hash), "=d" (len), "=c" (seed)),
>+ "0" (data), "1" (len), "2" (seed)
>+ : "memory", "cc");
>+
>+ return hash;
>+}
>+
>+#endif /* CONFIG_x86_64 */
>+
>+#else /* CONFIG_AS_CRC32 */
>+
>+u32 __jhash(const void *data, u32 len, u32 seed);
>+
>+static inline u32 arch_fast_hash(const void *data, u32 len, u32 seed)
>+{
>+ return __jhash(data, len, seed);
>+}
>+
>+#endif
>
> #endif /* _ASM_X86_HASH_H */
>diff --git a/arch/x86/kernel/i386_ksyms_32.c b/arch/x86/kernel/i386_ksyms_32.c
>index 05fd74f..afb98da 100644
>--- a/arch/x86/kernel/i386_ksyms_32.c
>+++ b/arch/x86/kernel/i386_ksyms_32.c
>@@ -1,4 +1,5 @@
> #include <linux/module.h>
>+#include <linux/hash.h>
>
> #include <asm/checksum.h>
> #include <asm/pgtable.h>
>@@ -38,6 +39,11 @@ EXPORT_SYMBOL(strstr);
> EXPORT_SYMBOL(csum_partial);
> EXPORT_SYMBOL(empty_zero_page);
>
>+#ifdef CONFIG_AS_CRC32
>+EXPORT_SYMBOL(__sse42_crc32);
>+EXPORT_SYMBOL(__jhash_trampoline);
>+#endif
>+
> #ifdef CONFIG_PREEMPT
> EXPORT_SYMBOL(___preempt_schedule);
> #ifdef CONFIG_CONTEXT_TRACKING
>diff --git a/arch/x86/kernel/x8664_ksyms_64.c b/arch/x86/kernel/x8664_ksyms_64.c
>index 0406819..1094c13 100644
>--- a/arch/x86/kernel/x8664_ksyms_64.c
>+++ b/arch/x86/kernel/x8664_ksyms_64.c
>@@ -3,6 +3,7 @@
>
> #include <linux/module.h>
> #include <linux/smp.h>
>+#include <linux/hash.h>
>
> #include <net/checksum.h>
>
>@@ -42,6 +43,11 @@ EXPORT_SYMBOL(clear_page);
>
> EXPORT_SYMBOL(csum_partial);
>
>+#ifdef CONFIG_AS_CRC32
>+EXPORT_SYMBOL(__sse42_crc32);
>+EXPORT_SYMBOL(__jhash_trampoline);
>+#endif
>+
> /*
> * Export string functions. We normally rely on gcc builtin for most of these,
> * but gcc sometimes decides not to inline them.
>diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
>index db92793..168bbef 100644
>--- a/arch/x86/lib/Makefile
>+++ b/arch/x86/lib/Makefile
>@@ -23,7 +23,7 @@ lib-y += memcpy_$(BITS).o
> lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
> lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o
>
>-obj-y += msr.o msr-reg.o msr-reg-export.o hash.o
>+obj-y += msr.o msr-reg.o msr-reg-export.o jhash.o arch_hash.o
>
> ifeq ($(CONFIG_X86_32),y)
> obj-y += atomic64_32.o
>diff --git a/arch/x86/lib/arch_hash.S b/arch/x86/lib/arch_hash.S
>new file mode 100644
>index 0000000..ff526a4
>--- /dev/null
>+++ b/arch/x86/lib/arch_hash.S
>@@ -0,0 +1,192 @@
>+#include <linux/linkage.h>
>+#include <asm/dwarf2.h>
>+#include <asm/calling.h>
>+
>+#ifdef CONFIG_AS_CRC32
>+
>+#ifdef CONFIG_X86_64
>+
>+ENTRY(__jhash_trampoline)
>+ CFI_STARTPROC
>+
>+ pushq_cfi %rcx
>+ pushq_cfi %r8
>+ pushq_cfi %r9
>+ pushq_cfi %r10
>+ pushq_cfi %r11
>+
>+ call __jhash
>+
>+ popq_cfi %r11
>+ popq_cfi %r10
>+ popq_cfi %r9
>+ popq_cfi %r8
>+ popq_cfi %rcx
>+
>+ retq
>+
>+ CFI_ENDPROC
>+ENDPROC(__jhash_trampoline)
>+
>+ENTRY(__sse42_crc32)
>+ CFI_STARTPROC
>+
>+ movq %rdx, %rax
>+ cmpq $0x40, %rsi
>+ jb .Lcrc_32bytes
>+ subq $0x40, %rsi
>+
>+.Lcrc_64bytes:
>+ subq $0x40, %rsi
>+ crc32q 0*8(%rdi), %rax
>+ crc32q 1*8(%rdi), %rax
>+ crc32q 2*8(%rdi), %rax
>+ crc32q 3*8(%rdi), %rax
>+ crc32q 4*8(%rdi), %rax
>+ crc32q 5*8(%rdi), %rax
>+ crc32q 6*8(%rdi), %rax
>+ crc32q 7*8(%rdi), %rax
>+ leaq 8*8(%rdi), %rdi
>+ jae .Lcrc_64bytes
>+ addq $0x40, %rsi
>+
>+.Lcrc_32bytes:
>+ cmpq $0x20, %rsi
>+ jb .Lcrc_16bytes
>+
>+ subq $0x20, %rsi
>+ crc32q 0*8(%rdi), %rax
>+ crc32q 1*8(%rdi), %rax
>+ crc32q 2*8(%rdi), %rax
>+ crc32q 3*8(%rdi), %rax
>+ leaq 4*8(%rdi), %rdi
>+
>+.Lcrc_16bytes:
>+ cmpq $0x10, %rsi
>+ jb .Lcrc_8bytes
>+
>+ subq $0x10, %rsi
>+ crc32q 0*8(%rdi), %rax
>+ crc32q 1*8(%rdi), %rax
>+ leaq 2*8(%rdi), %rdi
>+
>+.Lcrc_8bytes:
>+ cmpq $0x8, %rsi
>+ jb .Lcrc_4bytes
>+
>+ subq $0x8, %rsi
>+ crc32q (%rdi), %rax
>+ leaq 1*8(%rdi), %rdi
>+
>+.Lcrc_4bytes:
>+ cmpq $0x4, %rsi
>+ jb .Lcrc_2bytes
>+
>+ subq $0x4, %rsi
>+ crc32l (%rdi), %eax
>+ leaq 1*4(%rdi), %rdi
>+
>+.Lcrc_2bytes:
>+ cmpq $0x2, %rsi
>+ jb .Lcrc_1bytes
>+
>+ subq $0x2, %rsi
>+ crc32w (%rdi), %eax
>+ leaq 1*2(%rdi), %rdi
>+
>+.Lcrc_1bytes:
>+ cmpq $0x1, %rsi
>+ jb .Lend
>+
>+ crc32b (%rdi), %eax
>+.Lend:
>+ retq
>+ CFI_ENDPROC
>+ENDPROC(__sse42_crc32)
>+
>+#else /* CONFIG_X86_32 */
>+
>+ENTRY(__jhash_trampoline)
>+ CFI_STARTPROC
>+
>+ call __jhash
>+
>+ retl
>+ CFI_ENDPROC
>+ENDPROC(__jhash_trampoline)
>+
>+ENTRY(__sse42_crc32)
>+ CFI_STARTPROC
>+
>+ xchgl %eax,%ecx
>+ xchgl %edx,%ecx
>+
>+ cmpl $0x20, %ecx
>+ jb .Lcrc_16bytes
>+ subl $0x20, %ecx
>+
>+.Lcrc_32bytes:
>+ subl $0x20, %ecx
>+ crc32l 0*4(%edx), %eax
>+ crc32l 1*4(%edx), %eax
>+ crc32l 2*4(%edx), %eax
>+ crc32l 3*4(%edx), %eax
>+ crc32l 4*4(%edx), %eax
>+ crc32l 5*4(%edx), %eax
>+ crc32l 6*4(%edx), %eax
>+ crc32l 7*4(%edx), %eax
>+ leal 8*4(%edx), %edx
>+ jae .Lcrc_32bytes
>+ addl $0x20, %ecx
>+
>+.Lcrc_16bytes:
>+ cmpl $0x10, %ecx
>+ jb .Lcrc_8bytes
>+
>+ subl $0x10, %ecx
>+ crc32l 0*4(%edx), %eax
>+ crc32l 1*4(%edx), %eax
>+ crc32l 2*4(%edx), %eax
>+ crc32l 3*4(%edx), %eax
>+ leal 4*4(%edx), %edx
>+
>+.Lcrc_8bytes:
>+ cmpl $0x8, %ecx
>+ jb .Lcrc_4bytes
>+
>+ subl $0x8, %ecx
>+ crc32l 0*4(%edx), %eax
>+ crc32l 1*4(%edx), %eax
>+ leal 2*4(%edx), %edx
>+
>+.Lcrc_4bytes:
>+ cmpl $0x4, %ecx
>+ jb .Lcrc_2bytes
>+
>+ subl $0x4, %ecx
>+ crc32l 0*4(%edx), %eax
>+ leal 1*4(%edx), %edx
>+
>+.Lcrc_2bytes:
>+ cmpl $0x2, %ecx
>+ jb .Lcrc_1bytes
>+
>+ subl $0x2, %ecx
>+ crc32w (%edx), %eax
>+ leal 1*2(%edx), %edx
>+
>+.Lcrc_1bytes:
>+ cmpl $0x1, %ecx
>+ jb .Lend
>+
>+ crc32b (%edx), %eax
>+
>+.Lend:
>+ retl
>+
>+ CFI_ENDPROC
>+ENDPROC(__sse42_crc32)
>+
>+#endif
>+
>+#endif /* CONFIG_AS_CRC32 */
>diff --git a/arch/x86/lib/hash.c b/arch/x86/lib/hash.c
>deleted file mode 100644
>index ff4fa51..0000000
>--- a/arch/x86/lib/hash.c
>+++ /dev/null
>@@ -1,92 +0,0 @@
>-/*
>- * Some portions derived from code covered by the following notice:
>- *
>- * Copyright (c) 2010-2013 Intel Corporation. All rights reserved.
>- * All rights reserved.
>- *
>- * Redistribution and use in source and binary forms, with or without
>- * modification, are permitted provided that the following conditions
>- * are met:
>- *
>- * * Redistributions of source code must retain the above copyright
>- * notice, this list of conditions and the following disclaimer.
>- * * Redistributions in binary form must reproduce the above copyright
>- * notice, this list of conditions and the following disclaimer in
>- * the documentation and/or other materials provided with the
>- * distribution.
>- * * Neither the name of Intel Corporation nor the names of its
>- * contributors may be used to endorse or promote products derived
>- * from this software without specific prior written permission.
>- *
>- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
>- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
>- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
>- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
>- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
>- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
>- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
>- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
>- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
>- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
>- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
>- */
>-
>-#include <linux/hash.h>
>-#include <linux/init.h>
>-
>-#include <asm/processor.h>
>-#include <asm/cpufeature.h>
>-#include <asm/hash.h>
>-
>-static inline u32 crc32_u32(u32 crc, u32 val)
>-{
>-#ifdef CONFIG_AS_CRC32
>- asm ("crc32l %1,%0\n" : "+r" (crc) : "rm" (val));
>-#else
>- asm (".byte 0xf2, 0x0f, 0x38, 0xf1, 0xc1" : "+a" (crc) : "c" (val));
>-#endif
>- return crc;
>-}
>-
>-static u32 intel_crc4_2_hash(const void *data, u32 len, u32 seed)
>-{
>- const u32 *p32 = (const u32 *) data;
>- u32 i, tmp = 0;
>-
>- for (i = 0; i < len / 4; i++)
>- seed = crc32_u32(seed, *p32++);
>-
>- switch (len & 3) {
>- case 3:
>- tmp |= *((const u8 *) p32 + 2) << 16;
>- /* fallthrough */
>- case 2:
>- tmp |= *((const u8 *) p32 + 1) << 8;
>- /* fallthrough */
>- case 1:
>- tmp |= *((const u8 *) p32);
>- seed = crc32_u32(seed, tmp);
>- break;
>- }
>-
>- return seed;
>-}
>-
>-static u32 intel_crc4_2_hash2(const u32 *data, u32 len, u32 seed)
>-{
>- const u32 *p32 = (const u32 *) data;
>- u32 i;
>-
>- for (i = 0; i < len; i++)
>- seed = crc32_u32(seed, *p32++);
>-
>- return seed;
>-}
>-
>-void __init setup_arch_fast_hash(struct fast_hash_ops *ops)
>-{
>- if (cpu_has_xmm4_2) {
>- ops->hash = intel_crc4_2_hash;
>- ops->hash2 = intel_crc4_2_hash2;
>- }
>-}
>diff --git a/arch/x86/lib/jhash.c b/arch/x86/lib/jhash.c
>new file mode 100644
>index 0000000..ab4b408
>--- /dev/null
>+++ b/arch/x86/lib/jhash.c
>@@ -0,0 +1,6 @@
>+#include <linux/jhash.h>
>+
>+u32 __jhash(const void *data, u32 len, u32 seed)
>+{
>+ return jhash(data, len, seed);
>+}
>diff --git a/include/asm-generic/hash.h b/include/asm-generic/hash.h
>index b631284..07b8892 100644
>--- a/include/asm-generic/hash.h
>+++ b/include/asm-generic/hash.h
>@@ -1,9 +1,23 @@
> #ifndef __ASM_GENERIC_HASH_H
> #define __ASM_GENERIC_HASH_H
>
>-struct fast_hash_ops;
>-static inline void setup_arch_fast_hash(struct fast_hash_ops *ops)
>+#include <linux/jhash.h>
>+
>+/**
>+ * arch_fast_hash - Caclulates a hash over a given buffer that can have
>+ * arbitrary size. This function will eventually use an
>+ * architecture-optimized hashing implementation if
>+ * available, and trades off distribution for speed.
>+ *
>+ * @data: buffer to hash
>+ * @len: length of buffer in bytes
>+ * @seed: start seed
>+ *
>+ * Returns 32bit hash.
>+ */
>+u32 arch_fast_hash(const void *data, u32 len, u32 seed)
> {
>+ return jhash(data, len, seed);
> }
>
> #endif /* __ASM_GENERIC_HASH_H */
>diff --git a/include/linux/hash.h b/include/linux/hash.h
>index d0494c3..6e8fb02 100644
>--- a/include/linux/hash.h
>+++ b/include/linux/hash.h
>@@ -84,38 +84,4 @@ static inline u32 hash32_ptr(const void *ptr)
> return (u32)val;
> }
>
>-struct fast_hash_ops {
>- u32 (*hash)(const void *data, u32 len, u32 seed);
>- u32 (*hash2)(const u32 *data, u32 len, u32 seed);
>-};
>-
>-/**
>- * arch_fast_hash - Caclulates a hash over a given buffer that can have
>- * arbitrary size. This function will eventually use an
>- * architecture-optimized hashing implementation if
>- * available, and trades off distribution for speed.
>- *
>- * @data: buffer to hash
>- * @len: length of buffer in bytes
>- * @seed: start seed
>- *
>- * Returns 32bit hash.
>- */
>-extern u32 arch_fast_hash(const void *data, u32 len, u32 seed);
>-
>-/**
>- * arch_fast_hash2 - Caclulates a hash over a given buffer that has a
>- * size that is of a multiple of 32bit words. This
>- * function will eventually use an architecture-
>- * optimized hashing implementation if available,
>- * and trades off distribution for speed.
>- *
>- * @data: buffer to hash (must be 32bit padded)
>- * @len: number of 32bit words
>- * @seed: start seed
>- *
>- * Returns 32bit hash.
>- */
>-extern u32 arch_fast_hash2(const u32 *data, u32 len, u32 seed);
>-
> #endif /* _LINUX_HASH_H */
>diff --git a/lib/Makefile b/lib/Makefile
>index 0211d2b..4b9baa4 100644
>--- a/lib/Makefile
>+++ b/lib/Makefile
>@@ -26,7 +26,7 @@ obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
> bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \
> gcd.o lcm.o list_sort.o uuid.o flex_array.o iovec.o clz_ctz.o \
> bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o \
>- percpu-refcount.o percpu_ida.o hash.o rhashtable.o reciprocal_div.o
>+ percpu-refcount.o percpu_ida.o rhashtable.o reciprocal_div.o
> obj-y += string_helpers.o
> obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
> obj-y += kstrtox.o
>diff --git a/lib/hash.c b/lib/hash.c
>deleted file mode 100644
>index fea973f..0000000
>--- a/lib/hash.c
>+++ /dev/null
>@@ -1,39 +0,0 @@
>-/* General purpose hashing library
>- *
>- * That's a start of a kernel hashing library, which can be extended
>- * with further algorithms in future. arch_fast_hash{2,}() will
>- * eventually resolve to an architecture optimized implementation.
>- *
>- * Copyright 2013 Francesco Fusco <ffusco@...hat.com>
>- * Copyright 2013 Daniel Borkmann <dborkman@...hat.com>
>- * Copyright 2013 Thomas Graf <tgraf@...hat.com>
>- * Licensed under the GNU General Public License, version 2.0 (GPLv2)
>- */
>-
>-#include <linux/jhash.h>
>-#include <linux/hash.h>
>-#include <linux/cache.h>
>-
>-static struct fast_hash_ops arch_hash_ops __read_mostly = {
>- .hash = jhash,
>- .hash2 = jhash2,
>-};
>-
>-u32 arch_fast_hash(const void *data, u32 len, u32 seed)
>-{
>- return arch_hash_ops.hash(data, len, seed);
>-}
>-EXPORT_SYMBOL_GPL(arch_fast_hash);
>-
>-u32 arch_fast_hash2(const u32 *data, u32 len, u32 seed)
>-{
>- return arch_hash_ops.hash2(data, len, seed);
>-}
>-EXPORT_SYMBOL_GPL(arch_fast_hash2);
>-
>-static int __init hashlib_init(void)
>-{
>- setup_arch_fast_hash(&arch_hash_ops);
>- return 0;
>-}
>-early_initcall(hashlib_init);
>diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
>index e0a7fef..79bc65d 100644
>--- a/net/openvswitch/flow_table.c
>+++ b/net/openvswitch/flow_table.c
>@@ -366,7 +366,7 @@ static u32 flow_hash(const struct sw_flow_key *key, int key_start,
> /* Make sure number of hash bytes are multiple of u32. */
> BUILD_BUG_ON(sizeof(long) % sizeof(u32));
>
>- return arch_fast_hash2(hash_key, hash_u32s, 0);
>+ return arch_fast_hash(hash_key, hash_u32s, 0);
> }
>
> static int flow_key_start(const struct sw_flow_key *key)
>--
>1.9.3
---
-Jay Vosburgh, jay.vosburgh@...onical.com
--
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