From: Paolo Bonzini <pbonzini@redhat.com>
To: qemu-devel@nongnu.org
Cc: eesposit@redhat.com, vsementsov@virtuozzo.com,
stefanha@redhat.com, qemu-block@nongnu.org
Subject: [PATCH v2 3/6] coroutine-sleep: allow qemu_co_sleep_wake that wakes nothing
Date: Mon, 17 May 2021 12:05:45 +0200 [thread overview]
Message-ID: <20210517100548.28806-4-pbonzini@redhat.com> (raw)
In-Reply-To: <20210517100548.28806-1-pbonzini@redhat.com>
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>
---
block/block-copy.c | 4 +---
block/nbd.c | 8 ++------
util/qemu-coroutine-sleep.c | 21 ++++++++++++---------
3 files changed, 15 insertions(+), 18 deletions(-)
diff --git a/block/block-copy.c b/block/block-copy.c
index 9b4af00614..f896dc56f2 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -674,9 +674,7 @@ out:
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);
}
/*
diff --git a/block/nbd.c b/block/nbd.c
index 1d4668d42d..1c6315b168 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -289,9 +289,7 @@ static void coroutine_fn nbd_client_co_drain_begin(BlockDriverState *bs)
BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
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);
@@ -330,9 +328,7 @@ static void nbd_teardown_connection(BlockDriverState *bs)
s->state = NBD_CLIENT_QUIT;
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);
}
if (qemu_in_coroutine()) {
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();
--
2.31.1
next prev parent reply other threads:[~2021-05-17 10:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-17 10:05 [PATCH v2 0/6] coroutine: new sleep/wake API Paolo Bonzini
2021-05-17 10:05 ` [PATCH v2 1/6] coroutine-sleep: use a stack-allocated timer Paolo Bonzini
2021-05-17 10:05 ` [PATCH v2 2/6] coroutine-sleep: disallow NULL QemuCoSleepState** argument Paolo Bonzini
2021-05-17 10:05 ` Paolo Bonzini [this message]
2021-05-17 10:05 ` [PATCH v2 4/6] coroutine-sleep: move timer out of QemuCoSleepState Paolo Bonzini
2021-05-17 10:05 ` [PATCH v2 5/6] coroutine-sleep: replace QemuCoSleepState pointer with struct in the API Paolo Bonzini
2021-05-17 10:05 ` [PATCH v2 6/6] coroutine-sleep: introduce qemu_co_sleep Paolo Bonzini
2021-05-21 14:44 ` [PATCH v2 0/6] coroutine: new sleep/wake API Stefan Hajnoczi
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