pthread_rwlock_rdlock() and pthread_rwlock_wrlock() can fail if a
deadlock condition is detected or the current thread already owns
the lock. They can also fail, like pthread_rwlock_unlock(), if the
mutex wasn't properly initialized. None of these are ever expected
to happen with fv_VuDev::vu_dispatch_rwlock.
Some users already check the return value and assert, some others
don't. Introduce rdlock/wrlock/unlock wrappers that just do the
former and use them everywhere.
Signed-off-by: Greg Kurz <gr...@kaod.org>
---
tools/virtiofsd/fuse_virtio.c | 42 +++++++++++++++++++++++------------
1 file changed, 28 insertions(+), 14 deletions(-)
diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
index ddcefee4272f..7ea269c4b65d 100644
--- a/tools/virtiofsd/fuse_virtio.c
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -187,6 +187,24 @@ static void copy_iov(struct iovec *src_iov, int src_count,
}
}
+/*
+ * pthread_rwlock_rdlock() and pthread_rwlock_wrlock can fail if
+ * a deadlock condition is detected or the current thread already
+ * owns the lock. They can also fail, like pthread_rwlock_unlock(),
+ * if the mutex wasn't properly initialized. None of these are ever
+ * expected to happen.
+ */
+#define VU_DISPATCH_LOCK_OP(op) \
+static inline void vu_dispatch_##op(struct fv_VuDev *vud) \
+{ \
+ int ret = pthread_rwlock_##op(&vud->vu_dispatch_rwlock); \
+ assert(ret == 0); \
+}
+
+VU_DISPATCH_LOCK_OP(rdlock);
+VU_DISPATCH_LOCK_OP(wrlock);
+VU_DISPATCH_LOCK_OP(unlock);
+
/*
* Called back by ll whenever it wants to send a reply/message back
* The 1st element of the iov starts with the fuse_out_header
@@ -240,12 +258,12 @@ int virtio_send_msg(struct fuse_session *se, struct
fuse_chan *ch,
copy_iov(iov, count, in_sg, in_num, tosend_len);
- pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
+ vu_dispatch_rdlock(qi->virtio_dev);
pthread_mutex_lock(&qi->vq_lock);
vu_queue_push(dev, q, elem, tosend_len);
vu_queue_notify(dev, q);
pthread_mutex_unlock(&qi->vq_lock);
- pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock);
+ vu_dispatch_unlock(qi->virtio_dev);
req->reply_sent = true;
@@ -403,12 +421,12 @@ int virtio_send_data_iov(struct fuse_session *se, struct
fuse_chan *ch,
ret = 0;
- pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
+ vu_dispatch_rdlock(qi->virtio_dev);
pthread_mutex_lock(&qi->vq_lock);
vu_queue_push(dev, q, elem, tosend_len);
vu_queue_notify(dev, q);
pthread_mutex_unlock(&qi->vq_lock);
- pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock);
+ vu_dispatch_unlock(qi->virtio_dev);
err:
if (ret == 0) {
@@ -558,12 +576,12 @@ out:
fuse_log(FUSE_LOG_DEBUG, "%s: elem %d no reply sent\n", __func__,
elem->index);
- pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
+ vu_dispatch_rdlock(qi->virtio_dev);
pthread_mutex_lock(&qi->vq_lock);
vu_queue_push(dev, q, elem, 0);
vu_queue_notify(dev, q);
pthread_mutex_unlock(&qi->vq_lock);
- pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock);
+ vu_dispatch_unlock(qi->virtio_dev);
}
pthread_mutex_destroy(&req->ch.lock);
@@ -596,7 +614,6 @@ static void *fv_queue_thread(void *opaque)
qi->qidx, qi->kick_fd);
while (1) {
struct pollfd pf[2];
- int ret;
pf[0].fd = qi->kick_fd;
pf[0].events = POLLIN;
@@ -645,8 +662,7 @@ static void *fv_queue_thread(void *opaque)
break;
}
/* Mutual exclusion with virtio_loop() */
- ret = pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
- assert(ret == 0); /* there is no possible error case */
+ vu_dispatch_wrlock(qi->virtio_dev);
pthread_mutex_lock(&qi->vq_lock);
/* out is from guest, in is too guest */
unsigned int in_bytes, out_bytes;
@@ -672,7 +688,7 @@ static void *fv_queue_thread(void *opaque)
}
pthread_mutex_unlock(&qi->vq_lock);
- pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock);
+ vu_dispatch_unlock(qi->virtio_dev);
/* Process all the requests. */
if (!se->thread_pool_size && req_list != NULL) {
@@ -799,7 +815,6 @@ int virtio_loop(struct fuse_session *se)
while (!fuse_session_exited(se)) {
struct pollfd pf[1];
bool ok;
- int ret;
pf[0].fd = se->vu_socketfd;
pf[0].events = POLLIN;
pf[0].revents = 0;
@@ -825,12 +840,11 @@ int virtio_loop(struct fuse_session *se)
assert(pf[0].revents & POLLIN);
fuse_log(FUSE_LOG_DEBUG, "%s: Got VU event\n", __func__);
/* Mutual exclusion with fv_queue_thread() */
- ret = pthread_rwlock_wrlock(&se->virtio_dev->vu_dispatch_rwlock);
- assert(ret == 0); /* there is no possible error case */
+ vu_dispatch_wrlock(se->virtio_dev);
ok = vu_dispatch(&se->virtio_dev->dev);
- pthread_rwlock_unlock(&se->virtio_dev->vu_dispatch_rwlock);
+ vu_dispatch_unlock(se->virtio_dev);
if (!ok) {
fuse_log(FUSE_LOG_ERR, "%s: vu_dispatch failed\n", __func__);
--
2.26.2
