At Mon, 11 Mar 2013 15:39:05 +0100,
Stefan Hajnoczi wrote:
>
> On Mon, Mar 11, 2013 at 06:01:02PM +0900, MORITA Kazutaka wrote:
> > If an io_flush handler is not set, qemu_aio_wait doesn't invoke
> > callbacks.
> >
> > Signed-off-by: MORITA Kazutaka <morita.kazut...@lab.ntt.co.jp>
> > ---
> > block/sheepdog.c | 11 +++++++++--
> > 1 file changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/block/sheepdog.c b/block/sheepdog.c
> > index e4ec32d..cb0eeed 100644
> > --- a/block/sheepdog.c
> > +++ b/block/sheepdog.c
> > @@ -501,6 +501,13 @@ static void restart_co_req(void *opaque)
> > qemu_coroutine_enter(co, NULL);
> > }
> >
> > +static int have_co_req(void *opaque)
> > +{
> > + /* this handler is set only when there is a pending request, so
> > + * always returns 1. */
> > + return 1;
> > +}
> > +
> > typedef struct SheepdogReqCo {
> > int sockfd;
> > SheepdogReq *hdr;
> > @@ -523,14 +530,14 @@ static coroutine_fn void do_co_req(void *opaque)
> > unsigned int *rlen = srco->rlen;
> >
> > co = qemu_coroutine_self();
> > - qemu_aio_set_fd_handler(sockfd, NULL, restart_co_req, NULL, co);
> > + qemu_aio_set_fd_handler(sockfd, NULL, restart_co_req, have_co_req, co);
> >
> > ret = send_co_req(sockfd, hdr, data, wlen);
>
> Which tree is this patch against? block/sheepdog.c:do_co_req() has a
> socket_set_block(sockfd) call before this line.
Sorry, I have another patch in my local tree that needed to be sent
before this one. I'll send v2 including the missing patch.
>
> Is there a guarantee that only one coroutine executes do_co_req() at a
> time? Otherwise the first coroutine that finishes the function sets
> io_flush to NULL even though there's still another request processing.
Yes - the sockfd is opened just before calling do_req() and is closed
just after returning the function, so the sheepdog driver cannot call
multiple do_co_req() at a time against the same socket descriptor.
Thanks,
Kazutaka
