Paolo Bonzini <pbonz...@redhat.com> writes:
> blkdebug events can be called from either non-coroutine or coroutine
> contexts. However, some actions (specifically suspend actions and
> errors reported with immediately=off) only make sense from within
> a coroutine.
>
> Currently, using those action would lead to an abort() in
> qemu_coroutine_yield() ("Co-routine is yielding to no one").
> Catch them and print an error instead.
>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
> block/blkdebug.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/block/blkdebug.c b/block/blkdebug.c
> index bbf2948703..bf0aedb17d 100644
> --- a/block/blkdebug.c
> +++ b/block/blkdebug.c
> @@ -31,6 +31,7 @@
> #include "block/qdict.h"
> #include "qemu/module.h"
> #include "qemu/option.h"
> +#include "qemu/error-report.h"
> #include "qapi/qapi-visit-block-core.h"
> #include "qapi/qmp/qdict.h"
> #include "qapi/qmp/qlist.h"
> @@ -623,8 +624,13 @@ static int rule_check(BlockDriverState *bs, uint64_t
> offset, uint64_t bytes,
>
> qemu_mutex_unlock(&s->lock);
> if (!immediately) {
> - aio_co_schedule(qemu_get_current_aio_context(),
> qemu_coroutine_self());
> - qemu_coroutine_yield();
> + if (qemu_in_coroutine()) {
> + aio_co_schedule(qemu_get_current_aio_context(),
> qemu_coroutine_self());
> + qemu_coroutine_yield();
> + } else {
> + error_report("Non-coroutine event %s needs immediately = off\n",
> + BlkdebugEvent_lookup.array[rule->event]);
rule_check() is called from blkdebug_co_preadv(), blkdebug_co_pwritev(),
blkdebug_co_pwrite_zeroes(), blkdebug_co_pdiscard(),
blkdebug_co_block_status() (all marked coroutine_fn), and
blkdebug_co_flush() (which looks like it should be marked coroutine_fn).
Ignorant question: how could it be called outside coroutine context?
Also, code smell: reporting an error without taking an error path. But
let's worry about that only after I understand the problem you're trying
to fix.
> + }
> }
>
> return -error;
> @@ -858,7 +864,12 @@ static void blkdebug_debug_event(BlockDriverState *bs,
> BlkdebugEvent event)
> }
>
> while (actions_count[ACTION_SUSPEND] > 0) {
> - qemu_coroutine_yield();
> + if (qemu_in_coroutine()) {
> + qemu_coroutine_yield();
> + } else {
> + error_report("Non-coroutine event %s cannot suspend\n",
> + BlkdebugEvent_lookup.array[event]);
> + }
> actions_count[ACTION_SUSPEND]--;
> }
> }
