[PATCH v2 2/3] x86/hash: swap arguments passed to crc32_u32()

[PATCH v2 2/3] x86/hash: swap arguments passed to crc32_u32()

[Jan Beulich]

... to match the function's parameters. While reportedly commutative,
using the proper order allows for leveraging the instruction permitting
the source operand to be in memory.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Francesco Fusco <ffusco@redhat.com>
Cc: Thomas Graf <tgraf@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
---
v2: now swapping arguments rather than parameters, as requested by hpa
---
 arch/x86/lib/hash.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- 3.14-rc4-x86-hash-crc32.orig/arch/x86/lib/hash.c
+++ 3.14-rc4-x86-hash-crc32/arch/x86/lib/hash.c
@@ -53,7 +53,7 @@ static u32 intel_crc4_2_hash(const void 
 	u32 i, tmp = 0;
 
 	for (i = 0; i < len / 4; i++)
-		seed = crc32_u32(*p32++, seed);
+		seed = crc32_u32(seed, *p32++);
 
 	switch (3 - (len & 0x03)) {
 	case 0:
@@ -64,7 +64,7 @@ static u32 intel_crc4_2_hash(const void 
 		/* fallthrough */
 	case 2:
 		tmp |= *((const u8 *) p32);
-		seed = crc32_u32(tmp, seed);
+		seed = crc32_u32(seed, tmp);
 	default:
 		break;
 	}
@@ -78,7 +78,7 @@ static u32 intel_crc4_2_hash2(const u32 
 	u32 i;
 
 	for (i = 0; i < len; i++)
-		seed = crc32_u32(*p32++, seed);
+		seed = crc32_u32(seed, *p32++);
 
 	return seed;
 }

Re: [PATCH v2 2/3] x86/hash: swap arguments passed to crc32_u32()

[H. Peter Anvin]

On 02/27/2014 12:47 AM, Jan Beulich wrote:
> ... to match the function's parameters. While reportedly commutative,
> using the proper order allows for leveraging the instruction permitting
> the source operand to be in memory.
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> Acked-by: Daniel Borkmann <dborkman@redhat.com>
> Cc: Francesco Fusco <ffusco@redhat.com>
> Cc: Thomas Graf <tgraf@redhat.com>
> Cc: David S. Miller <davem@davemloft.net>

Acked-by: H. Peter Anvin <hpa@zytor.com>

[tip:x86/hash] x86, hash: Swap arguments passed to crc32_u32()

[tip-bot for Jan Beulich]

Commit-ID:  bbe831de1924f56596848919f98b195ed250fd28
Gitweb:     http://git.kernel.org/tip/bbe831de1924f56596848919f98b195ed250fd28
Author:     Jan Beulich <JBeulich@suse.com>
AuthorDate: Thu, 27 Feb 2014 08:47:34 +0000
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Wed, 19 Mar 2014 16:26:14 -0700

x86, hash: Swap arguments passed to crc32_u32()

... to match the function's parameters. While reportedly commutative,
using the proper order allows for leveraging the instruction permitting
the source operand to be in memory.

[ hpa: This code originated in the dpdk toolkit.  This was a bug in dpdk
  which has recently been fixed in part due to an earlier version of
  this patch. ]

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/530F09B6020000780011FBEB@nat28.tlf.novell.com
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Francesco Fusco <ffusco@redhat.com>
Cc: Thomas Graf <tgraf@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
 arch/x86/lib/hash.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/lib/hash.c b/arch/x86/lib/hash.c
index 060cc44..ac628aa 100644
--- a/arch/x86/lib/hash.c
+++ b/arch/x86/lib/hash.c
@@ -53,7 +53,7 @@ static u32 intel_crc4_2_hash(const void *data, u32 len, u32 seed)
 	u32 i, tmp = 0;
 
 	for (i = 0; i < len / 4; i++)
-		seed = crc32_u32(*p32++, seed);
+		seed = crc32_u32(seed, *p32++);
 
 	switch (3 - (len & 0x03)) {
 	case 0:
@@ -64,7 +64,7 @@ static u32 intel_crc4_2_hash(const void *data, u32 len, u32 seed)
 		/* fallthrough */
 	case 2:
 		tmp |= *((const u8 *) p32);
-		seed = crc32_u32(tmp, seed);
+		seed = crc32_u32(seed, tmp);
 	default:
 		break;
 	}
@@ -78,7 +78,7 @@ static u32 intel_crc4_2_hash2(const u32 *data, u32 len, u32 seed)
 	u32 i;
 
 	for (i = 0; i < len; i++)
-		seed = crc32_u32(*p32++, seed);
+		seed = crc32_u32(seed, *p32++);
 
 	return seed;
 }

[tip:x86/hash] x86, hash: Swap arguments passed to crc32_u32()

[tip-bot for Jan Beulich]

Commit-ID:  c5cdfdf90901c51363441365997eecd58efd9374
Gitweb:     http://git.kernel.org/tip/c5cdfdf90901c51363441365997eecd58efd9374
Author:     Jan Beulich <JBeulich@suse.com>
AuthorDate: Thu, 27 Feb 2014 08:47:34 +0000
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Wed, 19 Mar 2014 16:51:04 -0700

x86, hash: Swap arguments passed to crc32_u32()

... to match the function's parameters. While reportedly commutative,
using the proper order allows for leveraging the instruction permitting
the source operand to be in memory.

[ hpa: This code originated in the dpdk toolkit.  This was a bug in dpdk
  which has recently been fixed in part due to an earlier version of
  this patch. ]

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/530F09B6020000780011FBEB@nat28.tlf.novell.com
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Francesco Fusco <ffusco@redhat.com>
Cc: Thomas Graf <tgraf@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
 arch/x86/lib/hash.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/lib/hash.c b/arch/x86/lib/hash.c
index 060cc44..ac628aa 100644
--- a/arch/x86/lib/hash.c
+++ b/arch/x86/lib/hash.c
@@ -53,7 +53,7 @@ static u32 intel_crc4_2_hash(const void *data, u32 len, u32 seed)
 	u32 i, tmp = 0;
 
 	for (i = 0; i < len / 4; i++)
-		seed = crc32_u32(*p32++, seed);
+		seed = crc32_u32(seed, *p32++);
 
 	switch (3 - (len & 0x03)) {
 	case 0:
@@ -64,7 +64,7 @@ static u32 intel_crc4_2_hash(const void *data, u32 len, u32 seed)
 		/* fallthrough */
 	case 2:
 		tmp |= *((const u8 *) p32);
-		seed = crc32_u32(tmp, seed);
+		seed = crc32_u32(seed, tmp);
 	default:
 		break;
 	}
@@ -78,7 +78,7 @@ static u32 intel_crc4_2_hash2(const u32 *data, u32 len, u32 seed)
 	u32 i;
 
 	for (i = 0; i < len; i++)
-		seed = crc32_u32(*p32++, seed);
+		seed = crc32_u32(seed, *p32++);
 
 	return seed;
 }