From eaee0720851f22b273099eaf4c02722d9f24340a Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 17 May 2021 12:05:45 +0200 Subject: coroutine-sleep: allow qemu_co_sleep_wake that wakes nothing All callers of qemu_co_sleep_wake are checking whether they are passing a NULL argument inside the pointer-to-pointer: do the check in qemu_co_sleep_wake itself. As a side effect, qemu_co_sleep_wake can be called more than once and it will only wake the coroutine once; after the first time, the argument will be set to NULL via *sleep_state->user_state_pointer. However, this would not be safe unless co_sleep_cb keeps using the QemuCoSleepState* directly, so make it go through the pointer-to-pointer instead. Reviewed-by: Vladimir Sementsov-Ogievskiy Signed-off-by: Paolo Bonzini Message-id: 20210517100548.28806-4-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi --- util/qemu-coroutine-sleep.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) (limited to 'util') diff --git a/util/qemu-coroutine-sleep.c b/util/qemu-coroutine-sleep.c index 3f6f637e81..3ae2b5399a 100644 --- a/util/qemu-coroutine-sleep.c +++ b/util/qemu-coroutine-sleep.c @@ -27,19 +27,22 @@ struct QemuCoSleepState { void qemu_co_sleep_wake(QemuCoSleepState *sleep_state) { - /* Write of schedule protected by barrier write in aio_co_schedule */ - const char *scheduled = qatomic_cmpxchg(&sleep_state->co->scheduled, - qemu_co_sleep_ns__scheduled, NULL); + if (sleep_state) { + /* Write of schedule protected by barrier write in aio_co_schedule */ + const char *scheduled = qatomic_cmpxchg(&sleep_state->co->scheduled, + qemu_co_sleep_ns__scheduled, NULL); - assert(scheduled == qemu_co_sleep_ns__scheduled); - *sleep_state->user_state_pointer = NULL; - timer_del(&sleep_state->ts); - aio_co_wake(sleep_state->co); + assert(scheduled == qemu_co_sleep_ns__scheduled); + *sleep_state->user_state_pointer = NULL; + timer_del(&sleep_state->ts); + aio_co_wake(sleep_state->co); + } } static void co_sleep_cb(void *opaque) { - qemu_co_sleep_wake(opaque); + QemuCoSleepState **sleep_state = opaque; + qemu_co_sleep_wake(*sleep_state); } void coroutine_fn qemu_co_sleep_ns_wakeable(QEMUClockType type, int64_t ns, @@ -60,7 +63,7 @@ void coroutine_fn qemu_co_sleep_ns_wakeable(QEMUClockType type, int64_t ns, abort(); } - aio_timer_init(ctx, &state.ts, type, SCALE_NS, co_sleep_cb, &state); + aio_timer_init(ctx, &state.ts, type, SCALE_NS, co_sleep_cb, sleep_state); *sleep_state = &state; timer_mod(&state.ts, qemu_clock_get_ns(type) + ns); qemu_coroutine_yield(); -- cgit v1.2.3-55-g7522