On Mon, Nov 20, 2017 at 11:28:26AM +0000, Stefan Hajnoczi wrote:
> On Sun, Nov 19, 2017 at 09:46:43PM -0500, Jeff Cody wrote:
> > diff --git a/include/qemu/coroutine_int.h b/include/qemu/coroutine_int.h
> > index cb98892..931cdc9 100644
> > --- a/include/qemu/coroutine_int.h
> > +++ b/include/qemu/coroutine_int.h
> > @@ -53,6 +53,9 @@ struct Coroutine {
> >
> > /* Only used when the coroutine has yielded. */
> > AioContext *ctx;
> > +
> > + int scheduled;
>
> s/int/bool/
>
OK.
> > diff --git a/util/qemu-coroutine.c b/util/qemu-coroutine.c
> > index d6095c1..2edab63 100644
> > --- a/util/qemu-coroutine.c
> > +++ b/util/qemu-coroutine.c
> > @@ -109,6 +109,15 @@ void qemu_aio_coroutine_enter(AioContext *ctx,
> > Coroutine *co)
> >
> > trace_qemu_aio_coroutine_enter(ctx, self, co, co->entry_arg);
> >
> > + /* if the Coroutine has already been scheduled, entering it again will
> > + * cause us to enter it twice, potentially even after the coroutine has
> > + * been deleted */
> > + if (co->scheduled == 1) {
> > + fprintf(stderr, "Cannot enter a co-routine that has already "
> > + "been scheduled to run in a different
> > AioContext\n");
>
> This error message is too specific, the AioContext doesn't have to be
> different from the current one:
>
> block/blkdebug.c: aio_co_schedule(qemu_get_current_aio_context(),
> qemu_coroutine_self());
>
> If something calls qemu_aio_coroutine_enter() on the coroutine it might
> be from the same AioContext - but still an error condition worth failing
> loudly on.
>
Good point.
> I suggest simplifying the error message:
>
> fprintf(stderr, "Cannot enter a co-routine that has already "
> "been scheduled\n");
OK. I'll also change the wording here to what you have above, as well:
void aio_co_schedule(AioContext *ctx, Coroutine *co)
{
trace_aio_co_schedule(ctx, co);
+ if (co->scheduled == 1) {
+ fprintf(stderr,
+ "Cannot schedule a co-routine that is already scheduled\n");
+ abort();
+ }
+ co->scheduled = 1;
QSLIST_INSERT_HEAD_ATOMIC(&ctx->scheduled_coroutines,
co, co_scheduled_next);
Jeff
