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coroutine: Assert that no locks are held on termination

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A coroutine that takes a lock must also release it again. If the
coroutine terminates without having released all its locks, it's buggy
and we'll probably run into a deadlock sooner or later. Make sure that
we don't get such cases.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2016-08-11 17:51:59 +02:00
parent 0e438cdc93
commit 1b7f01d966
3 changed files with 13 additions and 0 deletions
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11
util/qemu-coroutine-lock.c
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@ -130,6 +130,7 @@ void coroutine_fn qemu_co_mutex_lock(CoMutex *mutex)
mutex->locked = true;
mutex->holder = self;
self->locks_held++;
trace_qemu_co_mutex_lock_return(mutex, self);
}
@ -146,6 +147,7 @@ void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex)
mutex->locked = false;
mutex->holder = NULL;
self->locks_held--;
qemu_co_queue_next(&mutex->queue);
trace_qemu_co_mutex_unlock_return(mutex, self);
@ -159,14 +161,19 @@ void qemu_co_rwlock_init(CoRwlock *lock)
void qemu_co_rwlock_rdlock(CoRwlock *lock)
{
Coroutine *self = qemu_coroutine_self();
while (lock->writer) {
qemu_co_queue_wait(&lock->queue);
}
lock->reader++;
self->locks_held++;
}
void qemu_co_rwlock_unlock(CoRwlock *lock)
{
Coroutine *self = qemu_coroutine_self();
assert(qemu_in_coroutine());
if (lock->writer) {
lock->writer = false;
@ -179,12 +186,16 @@ void qemu_co_rwlock_unlock(CoRwlock *lock)
qemu_co_queue_next(&lock->queue);
}
}
self->locks_held--;
}
void qemu_co_rwlock_wrlock(CoRwlock *lock)
{
Coroutine *self = qemu_coroutine_self();
while (lock->writer || lock->reader) {
qemu_co_queue_wait(&lock->queue);
}
lock->writer = true;
self->locks_held++;
}