| Message ID | 20210203182434.93870-1-groug@kaod.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] virtiofsd: vu_dispatch locking should never fail | expand |
On Wed, Feb 03, 2021 at 07:24:34PM +0100, Greg Kurz 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 <groug@kaod.org> > --- Reviewed-by: Vivek Goyal <vgoyal@redhat.com> Vivek > > 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 >
On Wed, Feb 03, 2021 at 07:24:34PM +0100, Greg Kurz 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 <groug@kaod.org> > --- > > 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(-) Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
* Greg Kurz (groug@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 <groug@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 > >
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__);
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 <groug@kaod.org> --- 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(-)