Re: [PATCH] net/txgbe: fix a bit with boolean operator

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu,  3 Mar 2022 21:31:00 +0800
Weiguo Li <liwg06@foxmail.com> wrote:

> On March 2, 2022, 5:23 p.m Ferruh Yigit wrote:
> > On 3/2/2022 8:02 AM, Jiawen Wu wrote:  
> > > On March 1, 2022 2:09 PM, Weiguo Li wrote:  
> > >> Since boolean value is in 0 and 1, it's strange to combines a boolean  
> > > value with  
> > >> a bit operator.
> > >>
> > >> Thus it's highly possible a typo error with "if (A & !B)", and more  
> > > probably to  
> > >> use "if (A & ~B)" instead.
> > >>
> > >> Fixes: c1d4e9d37abdc6 ("net/txgbe: add queue stats mapping")
> > >>
> > >> Signed-off-by: Weiguo Li <liwg06@foxmail.com>
> > >> ---
> > >>   drivers/net/txgbe/txgbe_ethdev.c | 2 +-
> > >>   1 file changed, 1 insertion(+), 1 deletion(-)
> > >>
> > >> diff --git a/drivers/net/txgbe/txgbe_ethdev.c
> > >> b/drivers/net/txgbe/txgbe_ethdev.c
> > >> index 19d4444748..f0994f028d 100644
> > >> --- a/drivers/net/txgbe/txgbe_ethdev.c
> > >> +++ b/drivers/net/txgbe/txgbe_ethdev.c
> > >> @@ -376,7 +376,7 @@ txgbe_dev_queue_stats_mapping_set(struct
> > >> rte_eth_dev *eth_dev,
> > >>   	if (hw->mac.type != txgbe_mac_raptor)
> > >>   		return -ENOSYS;
> > >>
> > >> -	if (stat_idx & !QMAP_FIELD_RESERVED_BITS_MASK)
> > >> +	if (stat_idx & ~QMAP_FIELD_RESERVED_BITS_MASK)
> > >>   		return -EIO;
> > >>
> > >>   	PMD_INIT_LOG(DEBUG, "Setting port %d, %s queue_id %d to stat
> > >> index %d",
> > >> --
> > >> 2.25.1  
> > > 
> > > Thanks.
> > > 
> > > Acked-by: Jiawen Wu <jiawenwu@trustnetic.com>
> > >   
> > 
> > Hi Weiguo,
> > 
> > Good catch, I wonder how did you detect this?
> > 
> > If there is an automated way, maybe we can consider using
> > it in our CI.
> >   
> 
> Hi Ferruh,
> 
> It's found by a coccinell script:
> 
> @fix_bit_boolean @ expression E; constant C; @@
> (
>   !E & !C
> |
> - !E & C
> + !(E & C)
> |
> - E & !C
> + E & ~C
> )
> 
> the idea came from a demo script in coccinelle website:
> (https://coccinelle.gitlabpages.inria.fr/website/rules/notand.html)
> 
> @@ expression E; constant C; @@
> (
>   !E & !C
> |
> - !E & C
> + !(E & C)
> )
> 
> The difference is in the last two lines and by which found the problem.
> 
> I'd be happy if it would used in CI.
> Maybe better to let Julia know, since she's the original author.
> cc Julia
> 
> -Weiguo
> 
> 

Could you add similar script to DPDK cocci scripts please?