Re: [PATCH v1] aio-posix: fix build failure io_uring 2.2

[Stefan Hajnoczi]

On Mon, Feb 21, 2022 at 04:43:55PM +0000, Wang, Haiyue wrote:
> > -----Original Message-----
> > From: Stefan Hajnoczi <stefanha@redhat.com>
> > Sent: Monday, February 21, 2022 22:54
> > To: Wang, Haiyue <haiyue.wang@intel.com>
> > Cc: qemu-devel@nongnu.org; Fam Zheng <fam@euphon.net>; open list:Block I/O 
> > path <qemu-block@nongnu.org>
> > Subject: Re: [PATCH v1] aio-posix: fix build failure io_uring 2.2
> > 
> > On Fri, Feb 18, 2022 at 12:16:27AM +0800, Haiyue Wang wrote:
> > > The io_uring fixed "Don't truncate addr fields to 32-bit on 32-bit":
> > > https://git.kernel.dk/cgit/liburing/commit/?id=d84c29b19ed0b130000619cff40141bb1fc3615b
> > >
> > > This leads to build failure:
> > > ../util/fdmon-io_uring.c: In function ‘add_poll_remove_sqe’:
> > > ../util/fdmon-io_uring.c:182:36: error: passing argument 2 of 
> > > ‘io_uring_prep_poll_remove’ makes
> > integer from pointer without a cast [-Werror=int-conversion]
> > >   182 |     io_uring_prep_poll_remove(sqe, node);
> > >       |                                    ^~~~
> > >       |                                    |
> > >       |                                    AioHandler *
> > > In file included from /root/io/qemu/include/block/aio.h:18,
> > >                  from ../util/aio-posix.h:20,
> > >                  from ../util/fdmon-io_uring.c:49:
> > > /usr/include/liburing.h:415:17: note: expected ‘__u64’ {aka ‘long long 
> > > unsigned int’} but argument
> > is of type ‘AioHandler *’
> > >   415 |           __u64 user_data)
> > >       |           ~~~~~~^~~~~~~~~
> > > cc1: all warnings being treated as errors
> > >
> > > So convert the paramter to right type according to the io_uring define.
> > >
> > > Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
> > > ---
> > >  util/fdmon-io_uring.c | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > >
> > > diff --git a/util/fdmon-io_uring.c b/util/fdmon-io_uring.c
> > > index 1461dfa407..e7febbf11f 100644
> > > --- a/util/fdmon-io_uring.c
> > > +++ b/util/fdmon-io_uring.c
> > > @@ -179,7 +179,11 @@ static void add_poll_remove_sqe(AioContext *ctx, 
> > > AioHandler *node)
> > >  {
> > >      struct io_uring_sqe *sqe = get_sqe(ctx);
> > >
> > > +#ifdef LIBURING_HAVE_DATA64
> > > +    io_uring_prep_poll_remove(sqe, (__u64)node);
> > > +#else
> > >      io_uring_prep_poll_remove(sqe, node);
> > > +#endif
> > >  }
> > 
> > Thanks for the patch. I suggest using the same approach as the liburing
> > commit to avoid the #ifdef:
> 
> Old version is "void *user_data", so need to use ' LIBURING_HAVE_DATA64',
> also, as the comment said:
> 
> /*
>  * Tell the app the have the 64-bit variants of the get/set userdata
>  */
> #define LIBURING_HAVE_DATA64
> 
> And yes, two casts seems be more safe: (__u64)(uintptr_t)node

You are right. I forgot that QEMU needs to support old liburing versions
too. The #ifdef is necessary.

Stefan

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