Re: [PATCH] hash: fix reading unaligned bits implementation

[Konstantin Ananyev]

Fixes: 28ebff11c2dc ("hash: add predictable RSS")
Cc: sta...@dpdk.org

Signed-off-by: Vladimir Medvedkin <vladimir.medved...@intel.com>
---
  lib/hash/rte_thash.c | 12 +++++++-----
  1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/lib/hash/rte_thash.c b/lib/hash/rte_thash.c
index 0249883b8d..2228af576b 100644
--- a/lib/hash/rte_thash.c
+++ b/lib/hash/rte_thash.c
@@ -670,7 +670,7 @@ rte_thash_get_gfni_matrices(struct rte_thash_ctx *ctx)
  }

static inline uint8_t

-read_unaligned_byte(uint8_t *ptr, unsigned int len, unsigned int offset)
+read_unaligned_byte(uint8_t *ptr, unsigned int offset)
  {
        uint8_t ret = 0;

@@ -681,13 +681,14 @@ read_unaligned_byte(uint8_t *ptr, unsigned int len, unsigned int offset)

                        (CHAR_BIT - (offset % CHAR_BIT));
        }

- return ret >> (CHAR_BIT - len);

+       return ret;
  }

static inline uint32_t

  read_unaligned_bits(uint8_t *ptr, int len, int offset)
  {
        uint32_t ret = 0;
+       int shift;

len = RTE_MAX(len, 0);

        len = RTE_MIN(len, (int)(sizeof(uint32_t) * CHAR_BIT));
@@ -695,13 +696,14 @@ read_unaligned_bits(uint8_t *ptr, int len, int offset)
        while (len > 0) {
                ret <<= CHAR_BIT;

- ret |= read_unaligned_byte(ptr, RTE_MIN(len, CHAR_BIT),

-                       offset);
+               ret |= read_unaligned_byte(ptr, offset);
                offset += CHAR_BIT;
                len -= CHAR_BIT;
        }

- return ret;

+       shift = (len == 0) ? 0 :
+               (CHAR_BIT - ((len + CHAR_BIT) % CHAR_BIT));
+       return ret >> shift;
  }

/* returns mask for len bits with given offset inside byte */

Acked-by: Konstantin Ananyev <konstantin.v.anan...@yandex.ru>
Tested-by: Konstantin Ananyev <konstantin.v.anan...@yandex.ru>