From 87d6a412bd1ed82c14cabd4b408003b23bbd2880 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Thu, 2 Sep 2010 14:05:30 +0300 Subject: vhost: fix attach to cgroups regression Since 2.6.36-rc1, non-root users of vhost-net fail to attach if they are in any cgroups. The reason is that when qemu uses vhost, vhost wants to attach its thread to all cgroups that qemu has. But we got the API backwards, so a non-priveledged process (Qemu) tried to control the priveledged one (vhost), which fails. Fix this by switching to the new cgroup_attach_task_all, and running it from the vhost thread. Signed-off-by: Michael S. Tsirkin --- drivers/vhost/vhost.c | 79 +++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 57 insertions(+), 22 deletions(-) (limited to 'drivers/vhost') diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 4b99117..1afa085 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -60,22 +60,25 @@ static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync, return 0; } +static void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn) +{ + INIT_LIST_HEAD(&work->node); + work->fn = fn; + init_waitqueue_head(&work->done); + work->flushing = 0; + work->queue_seq = work->done_seq = 0; +} + /* Init poll structure */ void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn, unsigned long mask, struct vhost_dev *dev) { - struct vhost_work *work = &poll->work; - init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup); init_poll_funcptr(&poll->table, vhost_poll_func); poll->mask = mask; poll->dev = dev; - INIT_LIST_HEAD(&work->node); - work->fn = fn; - init_waitqueue_head(&work->done); - work->flushing = 0; - work->queue_seq = work->done_seq = 0; + vhost_work_init(&poll->work, fn); } /* Start polling a file. We add ourselves to file's wait queue. The caller must @@ -95,35 +98,38 @@ void vhost_poll_stop(struct vhost_poll *poll) remove_wait_queue(poll->wqh, &poll->wait); } -/* Flush any work that has been scheduled. When calling this, don't hold any - * locks that are also used by the callback. */ -void vhost_poll_flush(struct vhost_poll *poll) +static void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work) { - struct vhost_work *work = &poll->work; unsigned seq; int left; int flushing; - spin_lock_irq(&poll->dev->work_lock); + spin_lock_irq(&dev->work_lock); seq = work->queue_seq; work->flushing++; - spin_unlock_irq(&poll->dev->work_lock); + spin_unlock_irq(&dev->work_lock); wait_event(work->done, ({ - spin_lock_irq(&poll->dev->work_lock); + spin_lock_irq(&dev->work_lock); left = seq - work->done_seq <= 0; - spin_unlock_irq(&poll->dev->work_lock); + spin_unlock_irq(&dev->work_lock); left; })); - spin_lock_irq(&poll->dev->work_lock); + spin_lock_irq(&dev->work_lock); flushing = --work->flushing; - spin_unlock_irq(&poll->dev->work_lock); + spin_unlock_irq(&dev->work_lock); BUG_ON(flushing < 0); } -void vhost_poll_queue(struct vhost_poll *poll) +/* Flush any work that has been scheduled. When calling this, don't hold any + * locks that are also used by the callback. */ +void vhost_poll_flush(struct vhost_poll *poll) +{ + vhost_work_flush(poll->dev, &poll->work); +} + +static inline void vhost_work_queue(struct vhost_dev *dev, + struct vhost_work *work) { - struct vhost_dev *dev = poll->dev; - struct vhost_work *work = &poll->work; unsigned long flags; spin_lock_irqsave(&dev->work_lock, flags); @@ -135,6 +141,11 @@ void vhost_poll_queue(struct vhost_poll *poll) spin_unlock_irqrestore(&dev->work_lock, flags); } +void vhost_poll_queue(struct vhost_poll *poll) +{ + vhost_work_queue(poll->dev, &poll->work); +} + static void vhost_vq_reset(struct vhost_dev *dev, struct vhost_virtqueue *vq) { @@ -236,6 +247,29 @@ long vhost_dev_check_owner(struct vhost_dev *dev) return dev->mm == current->mm ? 0 : -EPERM; } +struct vhost_attach_cgroups_struct { + struct vhost_work work; + struct task_struct *owner; + int ret; +}; + +static void vhost_attach_cgroups_work(struct vhost_work *work) +{ + struct vhost_attach_cgroups_struct *s; + s = container_of(work, struct vhost_attach_cgroups_struct, work); + s->ret = cgroup_attach_task_all(s->owner, current); +} + +static int vhost_attach_cgroups(struct vhost_dev *dev) +{ + struct vhost_attach_cgroups_struct attach; + attach.owner = current; + vhost_work_init(&attach.work, vhost_attach_cgroups_work); + vhost_work_queue(dev, &attach.work); + vhost_work_flush(dev, &attach.work); + return attach.ret; +} + /* Caller should have device mutex */ static long vhost_dev_set_owner(struct vhost_dev *dev) { @@ -255,10 +289,11 @@ static long vhost_dev_set_owner(struct vhost_dev *dev) } dev->worker = worker; - err = cgroup_attach_task_current_cg(worker); + wake_up_process(worker); /* avoid contributing to loadavg */ + + err = vhost_attach_cgroups(dev); if (err) goto err_cgroup; - wake_up_process(worker); /* avoid contributing to loadavg */ return 0; err_cgroup: -- cgit v1.1 From 615cc2211c17ed05a2a5d94abdac6c340a8ea508 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Thu, 2 Sep 2010 14:16:36 +0300 Subject: vhost: error handling fix vhost should set worker to NULL on cgroups attach failure, so that we won't try to destroy the worker again on close. Signed-off-by: Michael S. Tsirkin --- drivers/vhost/vhost.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/vhost') diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 1afa085..c579dcc 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -298,6 +298,7 @@ static long vhost_dev_set_owner(struct vhost_dev *dev) return 0; err_cgroup: kthread_stop(worker); + dev->worker = NULL; err_worker: if (dev->mm) mmput(dev->mm); -- cgit v1.1 From ee05d6939ed17b55e9c2466af32c208e0d547eb8 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Tue, 14 Sep 2010 15:15:52 +0200 Subject: vhost-net: fix range checking in mrg bufs case In mergeable buffer case, we use headcount, log_num and seg as indexes in same-size arrays, and we know that headcount <= seg and log_num equals either 0 or seg. Therefore, the right thing to do is range-check seg, not headcount as we do now: these will be different if guest chains s/g descriptors (this does not happen now, but we can not trust the guest). Long term, we should add BUG_ON checks to verify two other indexes are what we think they should be. Reported-by: Jason Wang Signed-off-by: Michael S. Tsirkin --- drivers/vhost/net.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/vhost') diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 29e850a..7c80082 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -243,7 +243,7 @@ static int get_rx_bufs(struct vhost_virtqueue *vq, int r, nlogs = 0; while (datalen > 0) { - if (unlikely(headcount >= VHOST_NET_MAX_SG)) { + if (unlikely(seg >= VHOST_NET_MAX_SG)) { r = -ENOBUFS; goto err; } -- cgit v1.1 From 5786aee8bf6d747ea59595601a19e78ad33d6929 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 22 Sep 2010 12:31:53 +0200 Subject: vhost: fix log ctx signalling The log eventfd signalling got put in dead code. We didn't notice because qemu currently does polling instead of eventfd select. Signed-off-by: Michael S. Tsirkin --- drivers/vhost/vhost.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'drivers/vhost') diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index c579dcc..dd3d6f7 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -858,11 +858,12 @@ int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, if (r < 0) return r; len -= l; - if (!len) + if (!len) { + if (vq->log_ctx) + eventfd_signal(vq->log_ctx, 1); return 0; + } } - if (vq->log_ctx) - eventfd_signal(vq->log_ctx, 1); /* Length written exceeds what we have stored. This is a bug. */ BUG(); return 0; -- cgit v1.1