* Greg Kurz (gr...@kaod.org) wrote:
> 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 for improved consistency and
> robustness.
>
> This is just cleanup. It doesn't fix any actual issue.
>
> Signed-off-by: Greg Kurz <gr...@kaod.org>
Queued
> ---
>
> v2: - open-code helpers instead of defining them with a macro (Vivek, Stefan)
> - fixed rd/wr typo in fv_queue_thread() (Stefan)
> - make it clear in the changelog this is just cleanup (Stefan)
>
> tools/virtiofsd/fuse_virtio.c | 49 +++++++++++++++++++++++++----------
> 1 file changed, 35 insertions(+), 14 deletions(-)
>
> diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
> index ddcefee4272f..523ee64fb7ae 100644
> --- a/tools/virtiofsd/fuse_virtio.c
> +++ b/tools/virtiofsd/fuse_virtio.c
> @@ -187,6 +187,31 @@ 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.
> + */
> +static void vu_dispatch_rdlock(struct fv_VuDev *vud)
> +{
> + int ret = pthread_rwlock_rdlock(&vud->vu_dispatch_rwlock);
> + assert(ret == 0);
> +}
> +
> +static void vu_dispatch_wrlock(struct fv_VuDev *vud)
> +{
> + int ret = pthread_rwlock_wrlock(&vud->vu_dispatch_rwlock);
> + assert(ret == 0);
> +}
> +
> +static void vu_dispatch_unlock(struct fv_VuDev *vud)
> +{
> + int ret = pthread_rwlock_unlock(&vud->vu_dispatch_rwlock);
> + assert(ret == 0);
> +}
> +
> /*
> * 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 +265,12 @@ 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 +428,12 @@ 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 +583,12 @@ 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 +621,6 @@ 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 +669,7 @@ 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_rdlock(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 +695,7 @@ 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 +822,6 @@ 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 +847,11 @@ 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
>
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
