mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-05-15 22:31:47 -04:00
Code Issues Packages Projects Releases Wiki Activity

MIPS: bcm63xx: nvram: avoid inefficient use of crc32_le_combine()

Browse Source 
bcm963xx_nvram_checksum() was using crc32_le_combine() to update a CRC
with four zero bytes.  However, this is about 5x slower than just
CRC'ing four zero bytes in the normal way.  Just do that instead.

(We could instead make crc32_le_combine() faster on short lengths.  But
all its callers do just fine without it, so I'd like to just remove it.)

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
This commit is contained in:
Eric Biggers
2025-05-11 11:28:36 -07:00
committed by Thomas Bogendoerfer
parent 3590692a13
commit 2695b3c7fe
1 changed files with 6 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
include/linux/bcm963xx_nvram.h
View File

@@ -81,25 +81,21 @@ static int __maybe_unused bcm963xx_nvram_checksum(
const struct bcm963xx_nvram *nvram,
u32 *expected_out, u32 *actual_out)
{
const u32 zero = 0;
u32 expected, actual;
size_t len;
if (nvram->version <= 4) {
expected = nvram->checksum_v4;
len = BCM963XX_NVRAM_V4_SIZE - sizeof(u32);
len = BCM963XX_NVRAM_V4_SIZE;
} else {
expected = nvram->checksum_v5;
len = BCM963XX_NVRAM_V5_SIZE - sizeof(u32);
len = BCM963XX_NVRAM_V5_SIZE;
}
/*
* Calculate the CRC32 value for the nvram with a checksum value
* of 0 without modifying or copying the nvram by combining:
* - The CRC32 of the nvram without the checksum value
* - The CRC32 of a zero checksum value (which is also 0)
*/
actual = crc32_le_combine(
crc32_le(~0, (u8 *)nvram, len), 0, sizeof(u32));
/* Calculate the CRC32 of the nvram with the checksum field set to 0. */
actual = crc32_le(~0, nvram, len - sizeof(u32));
actual = crc32_le(actual, &zero, sizeof(u32));
if (expected_out)
*expected_out = expected;