Thanks.
On Tue, Nov 26, 2019 at 07:33:30AM +0000, Yanqin Wei (Arm Technology China)
wrote:
> Hi Ben,
>
> Thanks for your time to review. I am sorry not to verify this patch by clang
> compiler. But this patch compiles successfully in gcc 7.4. Maybe in some gcc
> version, the atomic type is necessary for atomic operation.
> I will fix it in V2.
>
> Best Regards,
> Wei Yanqin
>
> > -----Original Message-----
> > From: Ben Pfaff <b...@ovn.org>
> > Sent: Tuesday, November 26, 2019 5:54 AM
> > To: Yanqin Wei (Arm Technology China) <yanqin....@arm.com>
> > Cc: d...@openvswitch.org; ovs-dev@openvswitch.org; nd <n...@arm.com>;
> > Gavin Hu (Arm Technology China) <gavin...@arm.com>
> > Subject: Re: [ovs-dev] [PATCH v1] netdev: use acquire-release semantics for
> > change_seq in netdev
> >
> > On Mon, Nov 18, 2019 at 10:46:59AM +0800, Yanqin Wei wrote:
> > > "rxq_enabled" of netdev is writen in the vhost thread and read by pmd
> > > thread once it observes 'change_seq' is updated. This patch is to keep
> > > order on aarch64 or other weak memory model CPU to ensure
> > > 'rxq_enabled' is observed before 'change_seq'.
> > >
> > > Reviewed-by: Gavin Hu <gavin...@arm.com>
> > > Signed-off-by: Yanqin Wei <yanqin....@arm.com>
> >
> > Thanks for the patch.
> >
> > This does not compile. Clang says:
> >
> > In file included from ../lib/dpif-netdev.c:54:
> > ../lib/netdev-provider.h:97:5: error: address argument to atomic
> > operation
> > must be a pointer to _Atomic type ('uint64_t *' (aka 'unsigned long *')
> > invalid)
> > ../lib/ovs-atomic-clang.h:82:16: note: expanded from macro
> > 'atomic_add_explicit'
> > In file included from ../lib/dpif-netdev.c:54:
> > ../lib/netdev-provider.h:99:9: error: address argument to atomic
> > operation
> > must be a pointer to _Atomic type ('uint64_t *' (aka 'unsigned long *')
> > invalid)
> > ../lib/ovs-atomic-clang.h:82:16: note: expanded from macro
> > 'atomic_add_explicit'
> > ../lib/netdev.c:2044:5: error: address argument to atomic operation
> > must be
> > a pointer to _Atomic type ('const uint64_t *' (aka 'const unsigned long *')
> > invalid)
> > ../lib/ovs-atomic-clang.h:53:15: note: expanded from macro
> > 'atomic_read_explicit'
> >
> > and many more instances.
> >
> > GCC says:
> >
> > ../lib/netdev.c:2044:5: error: incorrect type in argument 1 (different
> > modifiers)
> > ../lib/netdev.c:2044:5: expected void *
> > ../lib/netdev.c:2044:5: got unsigned long const *
> > ../lib/netdev.c:2044:5: error: incorrect type in argument 1 (different
> > modifiers)
> > ../lib/netdev.c:2044:5: expected void *
> > ../lib/netdev.c:2044:5: got unsigned long const *
> >
> > I do tend to think it's correct, otherwise. I wonder how this has been
> > missed
> > for so long.
> >
> > Thanks,
> >
> > Ben.
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