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coroutine-sleep: allow qemu_co_sleep_wake that wakes nothing

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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 <vsementsov@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20210517100548.28806-4-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini 2021-05-17 12:05:45 +02:00 committed by Stefan Hajnoczi
parent fb74a286fe
commit eaee072085
3 changed files with 15 additions and 18 deletions
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4
block/block-copy.c
View File

@ -674,9 +674,7 @@ out:
void block_copy_kick(BlockCopyCallState *call_state) void block_copy_kick(BlockCopyCallState *call_state)
{ {
if (call_state->sleep_state) { qemu_co_sleep_wake(call_state->sleep_state);
qemu_co_sleep_wake(call_state->sleep_state);
}
} }
/* /*

8
block/nbd.c
View File

@ -289,9 +289,7 @@ static void coroutine_fn nbd_client_co_drain_begin(BlockDriverState *bs)
BDRVNBDState *s = (BDRVNBDState *)bs->opaque; BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
s->drained = true; s->drained = true;
if (s->connection_co_sleep_ns_state) { qemu_co_sleep_wake(s->connection_co_sleep_ns_state);
qemu_co_sleep_wake(s->connection_co_sleep_ns_state);
}
nbd_co_establish_connection_cancel(bs, false); nbd_co_establish_connection_cancel(bs, false);
@ -330,9 +328,7 @@ static void nbd_teardown_connection(BlockDriverState *bs)
s->state = NBD_CLIENT_QUIT; s->state = NBD_CLIENT_QUIT;
if (s->connection_co) { if (s->connection_co) {
if (s->connection_co_sleep_ns_state) { qemu_co_sleep_wake(s->connection_co_sleep_ns_state);
qemu_co_sleep_wake(s->connection_co_sleep_ns_state);
}
nbd_co_establish_connection_cancel(bs, true); nbd_co_establish_connection_cancel(bs, true);
} }
if (qemu_in_coroutine()) { if (qemu_in_coroutine()) {

21
util/qemu-coroutine-sleep.c
View File

@ -27,19 +27,22 @@ struct QemuCoSleepState {
void qemu_co_sleep_wake(QemuCoSleepState *sleep_state) void qemu_co_sleep_wake(QemuCoSleepState *sleep_state)
{ {
/* Write of schedule protected by barrier write in aio_co_schedule */ if (sleep_state) {
const char *scheduled = qatomic_cmpxchg(&sleep_state->co->scheduled, /* Write of schedule protected by barrier write in aio_co_schedule */
qemu_co_sleep_ns__scheduled, NULL); const char *scheduled = qatomic_cmpxchg(&sleep_state->co->scheduled,
qemu_co_sleep_ns__scheduled, NULL);
assert(scheduled == qemu_co_sleep_ns__scheduled); assert(scheduled == qemu_co_sleep_ns__scheduled);
*sleep_state->user_state_pointer = NULL; *sleep_state->user_state_pointer = NULL;
timer_del(&sleep_state->ts); timer_del(&sleep_state->ts);
aio_co_wake(sleep_state->co); aio_co_wake(sleep_state->co);
}
} }
static void co_sleep_cb(void *opaque) 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, 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(); 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; *sleep_state = &state;
timer_mod(&state.ts, qemu_clock_get_ns(type) + ns); timer_mod(&state.ts, qemu_clock_get_ns(type) + ns);
qemu_coroutine_yield(); qemu_coroutine_yield();