On 1/26/2020 5:25 PM, David Harton wrote:
> Modified UPDATE_VF_STAT to properly handle rollover conditions.
>
> Fixes: d82170d27918 ("igb: add VF support")
> Cc: intel.com
>
> Signed-off-by: David Harton <dhar...@cisco.com>
> ---
> drivers/net/e1000/igb_ethdev.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/e1000/igb_ethdev.c b/drivers/net/e1000/igb_ethdev.c
> index a3e30dbe5..825663267 100644
> --- a/drivers/net/e1000/igb_ethdev.c
> +++ b/drivers/net/e1000/igb_ethdev.c
> @@ -261,11 +261,15 @@ static int igb_filter_restore(struct rte_eth_dev *dev);
> /*
> * Define VF Stats MACRO for Non "cleared on read" register
> */
> -#define UPDATE_VF_STAT(reg, last, cur) \
> -{ \
> - u32 latest = E1000_READ_REG(hw, reg); \
> - cur += (latest - last) & UINT_MAX; \
Why this is wrong? Both 'latest' and 'last' are 'u32', so diff should be correct
'u32' value. And it is added to 'u64' 'cur' value. What I am missing?
> - last = latest; \
> +#define UPDATE_VF_STAT(reg, last, cur) \
> +{ \
> + u32 latest = E1000_READ_REG(hw, reg); \
> + if (latest >= last) \
> + cur += (latest - last); \
> + else \
> + cur += ((latest + ((uint64_t)1 << 32)) - last); \
> + cur &= UINT_MAX; \
Why & with UINT_MAX, won't this limit the value to 32bits which has 64bit
storage?
> + last = latest; \
> }
>
> #define IGB_FC_PAUSE_TIME 0x0680
>
