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| author | Amit Shah <amit.shah@redhat.com> | 2013-03-29 11:00:08 (GMT) |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2013-03-30 03:55:46 (GMT) |
| commit | 9ba5c80b1aea8648a3efe5f22dc1f7cacdfbeeb8 (patch) | |
| tree | cdb191b7987323a4e454c9033ba4e449483ad57d | |
| parent | 165b1b8bbc17c9469b053bab78b11b7cbce6d161 (diff) | |
| download | linux-9ba5c80b1aea8648a3efe5f22dc1f7cacdfbeeb8.tar.xz | |
virtio: console: add locking around c_ovq operations
When multiple ovq operations are being performed (lots of open/close
operations on virtio_console fds), the __send_control_msg() function can
get confused without locking.
A simple recipe to cause badness is:
* create a QEMU VM with two virtio-serial ports
* in the guest, do
while true;do echo abc >/dev/vport0p1;done
while true;do echo edf >/dev/vport0p2;done
In one run, this caused a panic in __send_control_msg(). In another, I
got
virtio_console virtio0: control-o:id 0 is not a head!
This also results repeated messages similar to these on the host:
qemu-kvm: virtio-serial-bus: Unexpected port id 478762112 for device virtio-serial-bus.0
qemu-kvm: virtio-serial-bus: Unexpected port id 478762368 for device virtio-serial-bus.0
Reported-by: FuXiangChun <xfu@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Reviewed-by: Asias He <asias@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
| -rw-r--r-- | drivers/char/virtio_console.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 2dd9134..ce5f3fc 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -150,6 +150,7 @@ struct ports_device { /* To protect the vq operations for the control channel */ spinlock_t c_ivq_lock; + spinlock_t c_ovq_lock; /* The current config space is stored here */ struct virtio_console_config config; @@ -569,11 +570,14 @@ static ssize_t __send_control_msg(struct ports_device *portdev, u32 port_id, vq = portdev->c_ovq; sg_init_one(sg, &cpkt, sizeof(cpkt)); + + spin_lock(&portdev->c_ovq_lock); if (virtqueue_add_buf(vq, sg, 1, 0, &cpkt, GFP_ATOMIC) == 0) { virtqueue_kick(vq); while (!virtqueue_get_buf(vq, &len)) cpu_relax(); } + spin_unlock(&portdev->c_ovq_lock); return 0; } @@ -1997,6 +2001,7 @@ static int virtcons_probe(struct virtio_device *vdev) unsigned int nr_added_bufs; spin_lock_init(&portdev->c_ivq_lock); + spin_lock_init(&portdev->c_ovq_lock); INIT_WORK(&portdev->control_work, &control_work_handler); nr_added_bufs = fill_queue(portdev->c_ivq, |