On 6/10/20 6:10 PM, Vladimir Sementsov-Ogievskiy wrote:
> 10.06.2020 17:41, Denis V. Lunev wrote:
>> The patch preserves the constraint that the only waiter is allowed.
>>
>> Signed-off-by: Denis V. Lunev <d...@openvz.org>
>> CC: Kevin Wolf <kw...@redhat.com>
>> CC: Max Reitz <mre...@redhat.com>
>> CC: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
>> CC: Denis Plotnikov <dplotni...@virtuozzo.com>
>> ---
>> block/aio_task.c | 8 ++++----
>> 1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/block/aio_task.c b/block/aio_task.c
>> index 88989fa248..f338049147 100644
>> --- a/block/aio_task.c
>> +++ b/block/aio_task.c
>> @@ -27,7 +27,7 @@
>> #include "block/aio_task.h"
>> struct AioTaskPool {
>> - Coroutine *main_co;
>> + Coroutine *wake_co;
>> int status;
>> int max_busy_tasks;
>> int busy_tasks;
>> @@ -54,15 +54,15 @@ static void coroutine_fn aio_task_co(void *opaque)
>> if (pool->waiting) {
>> pool->waiting = false;
>> - aio_co_wake(pool->main_co);
>> + aio_co_wake(pool->wake_co);
>> }
>> }
>> void coroutine_fn aio_task_pool_wait_one(AioTaskPool *pool)
>> {
>> assert(pool->busy_tasks > 0);
>> - assert(qemu_coroutine_self() == pool->main_co);
>> + pool->wake_co = qemu_coroutine_self();
>> pool->waiting = true;
>> qemu_coroutine_yield();
>> @@ -98,7 +98,7 @@ AioTaskPool *coroutine_fn aio_task_pool_new(int
>> max_busy_tasks)
>> {
>> AioTaskPool *pool = g_new0(AioTaskPool, 1);
>> - pool->main_co = qemu_coroutine_self();
>> + pool->wake_co = NULL;
>> pool->max_busy_tasks = max_busy_tasks;
>> return pool;
>>
>
> With such approach, if several coroutines will wait simultaneously,
> the only one will be finally woken and other will hang.
>
> I think, we should use CoQueue here: CoQueue instead of wake_co,
> qemu_co_queue_wait in wait_one, and qemu_co_queue_next instead of
> aio_co_wake.
>
>
I will make a check, but for now it would be enough to
add
assert(!pool->waiting);
at the beginning of aio_task_pool_wait_one
Den
