> -----邮件原件-----
> 发件人: Ananyev, Konstantin <konstantin.anan...@intel.com>
> 发送时间: Saturday, September 25, 2021 2:08 AM
> 收件人: Feifei Wang <feifei.wa...@arm.com>; Yigit, Ferruh
> <ferruh.yi...@intel.com>
> 抄送: dev@dpdk.org; nd <n...@arm.com>; sta...@dpdk.org; Ruifeng Wang
> <ruifeng.w...@arm.com>
> 主题: RE: [RFC PATCH v2 4/5] lib/bpf: use wait event scheme for Rx/Tx
> iteration
>
>
> >
> > First, fix the bug that keyword const of func arg should be after "*".
>
> I believe there is no bug here.
>
> > This is because const before "*" means the value of "cbi" should not
> > be changed.
>
> Exactly, it says that the function itself will not change the value of "cbi".
> It just waits for the value to be changed by someone else.
> So please keep parameter list intact.
Thanks for your explanation. The reason I changed is that I ever used
rte_wait_until_xx(validate *addr) API here,
And there is conflict between "const" and "validate", complier will report
warning here.
But now I think since I keep it as it is, there will be no warning due to new
macro has no "validate".
I will delete this unnecessary bug fix.
>
> > But we should monitor that cbi->use changed and then we can jump out
> > of loop.
> >
> > Second, instead of polling for cbi->use to be updated, use wait event
> > scheme.
> >
> > Fixes: a93ff62a8938 ("bpf: introduce basic Rx/Tx filters")
> > Cc: konstantin.anan...@intel.com
> > Cc: sta...@dpdk.org
> >
> > Signed-off-by: Feifei Wang <feifei.wa...@arm.com>
> > Reviewed-by: Ruifeng Wang <ruifeng.w...@arm.com>
> > ---
> > lib/bpf/bpf_pkt.c | 11 ++++-------
> > 1 file changed, 4 insertions(+), 7 deletions(-)
> >
> > diff --git a/lib/bpf/bpf_pkt.c b/lib/bpf/bpf_pkt.c index
> > 6e8248f0d6..08ed8ff68c 100644
> > --- a/lib/bpf/bpf_pkt.c
> > +++ b/lib/bpf/bpf_pkt.c
> > @@ -111,9 +111,9 @@ bpf_eth_cbi_unuse(struct bpf_eth_cbi *cbi)
> > * Waits till datapath finished using given callback.
> > */
> > static void
> > -bpf_eth_cbi_wait(const struct bpf_eth_cbi *cbi)
> > +bpf_eth_cbi_wait(struct bpf_eth_cbi *const cbi)
> > {
> > - uint32_t nuse, puse;
> > + uint32_t puse;
> >
> > /* make sure all previous loads and stores are completed */
> > rte_smp_mb();
> > @@ -122,11 +122,8 @@ bpf_eth_cbi_wait(const struct bpf_eth_cbi *cbi)
> >
> > /* in use, busy wait till current RX/TX iteration is finished */
> > if ((puse & BPF_ETH_CBI_INUSE) != 0) {
> > - do {
> > - rte_pause();
> > - rte_compiler_barrier();
> > - nuse = cbi->use;
> > - } while (nuse == puse);
> > + rte_compiler_barrier();
> > + rte_wait_event_32(&cbi->use, UINT_MAX, puse, ==,
> __ATOMIC_RELAXED);
> > }
> > }
> >
> > --
> > 2.25.1
