From 26b0b698c00bd9176f86c539aeb680481fa19473 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Mon, 5 Oct 2020 17:58:52 +0200 Subject: [PATCH] util/async: Add aio_co_reschedule_self() Add a function that can be used to move the currently running coroutine to a different AioContext (and therefore potentially a different thread). Signed-off-by: Kevin Wolf Reviewed-by: Stefan Hajnoczi Message-Id: <20201005155855.256490-12-kwolf@redhat.com> Reviewed-by: Markus Armbruster Reviewed-by: Stefan Hajnoczi Signed-off-by: Markus Armbruster --- include/block/aio.h | 10 ++++++++++ util/async.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+) diff --git a/include/block/aio.h b/include/block/aio.h index ec8c5af642..5f342267d5 100644 --- a/include/block/aio.h +++ b/include/block/aio.h @@ -17,6 +17,7 @@ #ifdef CONFIG_LINUX_IO_URING #include #endif +#include "qemu/coroutine.h" #include "qemu/queue.h" #include "qemu/event_notifier.h" #include "qemu/thread.h" @@ -655,6 +656,15 @@ static inline bool aio_node_check(AioContext *ctx, bool is_external) void aio_co_schedule(AioContext *ctx, struct Coroutine *co); /** + * aio_co_reschedule_self: + * @new_ctx: the new context + * + * Move the currently running coroutine to new_ctx. If the coroutine is already + * running in new_ctx, do nothing. + */ +void coroutine_fn aio_co_reschedule_self(AioContext *new_ctx); + +/** * aio_co_wake: * @co: the coroutine * diff --git a/util/async.c b/util/async.c index f758354c6a..674dbefb7c 100644 --- a/util/async.c +++ b/util/async.c @@ -569,6 +569,36 @@ void aio_co_schedule(AioContext *ctx, Coroutine *co) aio_context_unref(ctx); } +typedef struct AioCoRescheduleSelf { + Coroutine *co; + AioContext *new_ctx; +} AioCoRescheduleSelf; + +static void aio_co_reschedule_self_bh(void *opaque) +{ + AioCoRescheduleSelf *data = opaque; + aio_co_schedule(data->new_ctx, data->co); +} + +void coroutine_fn aio_co_reschedule_self(AioContext *new_ctx) +{ + AioContext *old_ctx = qemu_get_current_aio_context(); + + if (old_ctx != new_ctx) { + AioCoRescheduleSelf data = { + .co = qemu_coroutine_self(), + .new_ctx = new_ctx, + }; + /* + * We can't directly schedule the coroutine in the target context + * because this would be racy: The other thread could try to enter the + * coroutine before it has yielded in this one. + */ + aio_bh_schedule_oneshot(old_ctx, aio_co_reschedule_self_bh, &data); + qemu_coroutine_yield(); + } +} + void aio_co_wake(struct Coroutine *co) { AioContext *ctx; -- 2.11.4.GIT