linux-kernel - [PATCH] crc32: Don't reference unnecessary crc32 tables in single-bit mode

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Message-ID: <20120121003652.GD2749@tux1.beaverton.ibm.com>
Date:	Fri, 20 Jan 2012 16:36:52 -0800
From:	"Darrick J. Wong" <djwong@...ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Randy Dunlap <rdunlap@...otime.net>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>
Subject: [PATCH] crc32: Don't reference unnecessary crc32 tables in
	single-bit mode

When compiling with single bit mode (CRC32_BIT=y) we shouldn't reference the
crc32 tables, since they aren't built in single-bit mode.  Many thanks to Randy
Dunlap for finding this bug:
http://marc.info/?l=linux-kernel&m=132709702422141&w=2

This patch is against next-20120120.

Signed-off-by: Darrick J. Wong <djwong@...ibm.com>
---

 lib/crc32.c |   21 +++++++++++++++++++--
 1 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/lib/crc32.c b/lib/crc32.c
index ebc5911..b0d278f 100644
--- a/lib/crc32.c
+++ b/lib/crc32.c
@@ -174,16 +174,26 @@ static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,
 	return crc;
 }
 
+#if CRC_LE_BITS == 1
+u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
+{
+	return crc32_le_generic(crc, p, len, NULL, CRCPOLY_LE);
+}
+u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
+{
+	return crc32_le_generic(crc, p, len, NULL, CRC32C_POLY_LE);
+}
+#else
 u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
 {
 	return crc32_le_generic(crc, p, len, crc32table_le, CRCPOLY_LE);
 }
-EXPORT_SYMBOL(crc32_le);
-
 u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
 {
 	return crc32_le_generic(crc, p, len, crc32ctable_le, CRC32C_POLY_LE);
 }
+#endif
+EXPORT_SYMBOL(crc32_le);
 EXPORT_SYMBOL(__crc32c_le);
 
 /**
@@ -233,10 +243,17 @@ static inline u32 __pure crc32_be_generic(u32 crc, unsigned char const *p,
 	return crc;
 }
 
+#if CRC_LE_BITS == 1
+u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
+{
+	return crc32_be_generic(crc, p, len, NULL, CRCPOLY_BE);
+}
+#else
 u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
 {
 	return crc32_be_generic(crc, p, len, crc32table_be, CRCPOLY_BE);
 }
+#endif
 EXPORT_SYMBOL(crc32_be);
 
 #ifdef CONFIG_CRC32_SELFTEST

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