lkml.org 
[lkml]   [2022]   [Jun]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.17 714/772] um: virtio_uml: Fix broken device handling in time-travel
    Date
    From: Johannes Berg <johannes.berg@intel.com>

    commit af9fb41ed315ce95f659f0b10b4d59a71975381d upstream.

    If a device implementation crashes, virtio_uml will mark it
    as dead by calling virtio_break_device() and scheduling the
    work that will remove it.

    This still seems like the right thing to do, but it's done
    directly while reading the message, and if time-travel is
    used, this is in the time-travel handler, outside of the
    normal Linux machinery. Therefore, we cannot acquire locks
    or do normal "linux-y" things because e.g. lockdep will be
    confused about the context.

    Move handling this situation out of the read function and
    into the actual IRQ handler and response handling instead,
    so that in the case of time-travel we don't call it in the
    wrong context.

    Chances are the system will still crash immediately, since
    the device implementation crashing may also cause the time-
    travel controller to go down, but at least all of that now
    happens without strange warnings from lockdep.

    Fixes: c8177aba37ca ("um: time-travel: rework interrupt handling in ext mode")
    Cc: stable@vger.kernel.org
    Signed-off-by: Johannes Berg <johannes.berg@intel.com>
    Signed-off-by: Richard Weinberger <richard@nod.at>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/um/drivers/virtio_uml.c | 33 +++++++++++++++++++++++----------
    1 file changed, 23 insertions(+), 10 deletions(-)

    --- a/arch/um/drivers/virtio_uml.c
    +++ b/arch/um/drivers/virtio_uml.c
    @@ -63,6 +63,7 @@ struct virtio_uml_device {

    u8 config_changed_irq:1;
    uint64_t vq_irq_vq_map;
    + int recv_rc;
    };

    struct virtio_uml_vq_info {
    @@ -148,14 +149,6 @@ static int vhost_user_recv(struct virtio

    rc = vhost_user_recv_header(fd, msg);

    - if (rc == -ECONNRESET && vu_dev->registered) {
    - struct virtio_uml_platform_data *pdata;
    -
    - pdata = vu_dev->pdata;
    -
    - virtio_break_device(&vu_dev->vdev);
    - schedule_work(&pdata->conn_broken_wk);
    - }
    if (rc)
    return rc;
    size = msg->header.size;
    @@ -164,6 +157,21 @@ static int vhost_user_recv(struct virtio
    return full_read(fd, &msg->payload, size, false);
    }

    +static void vhost_user_check_reset(struct virtio_uml_device *vu_dev,
    + int rc)
    +{
    + struct virtio_uml_platform_data *pdata = vu_dev->pdata;
    +
    + if (rc != -ECONNRESET)
    + return;
    +
    + if (!vu_dev->registered)
    + return;
    +
    + virtio_break_device(&vu_dev->vdev);
    + schedule_work(&pdata->conn_broken_wk);
    +}
    +
    static int vhost_user_recv_resp(struct virtio_uml_device *vu_dev,
    struct vhost_user_msg *msg,
    size_t max_payload_size)
    @@ -171,8 +179,10 @@ static int vhost_user_recv_resp(struct v
    int rc = vhost_user_recv(vu_dev, vu_dev->sock, msg,
    max_payload_size, true);

    - if (rc)
    + if (rc) {
    + vhost_user_check_reset(vu_dev, rc);
    return rc;
    + }

    if (msg->header.flags != (VHOST_USER_FLAG_REPLY | VHOST_USER_VERSION))
    return -EPROTO;
    @@ -369,6 +379,7 @@ static irqreturn_t vu_req_read_message(s
    sizeof(msg.msg.payload) +
    sizeof(msg.extra_payload));

    + vu_dev->recv_rc = rc;
    if (rc)
    return IRQ_NONE;

    @@ -412,7 +423,9 @@ static irqreturn_t vu_req_interrupt(int
    if (!um_irq_timetravel_handler_used())
    ret = vu_req_read_message(vu_dev, NULL);

    - if (vu_dev->vq_irq_vq_map) {
    + if (vu_dev->recv_rc) {
    + vhost_user_check_reset(vu_dev, vu_dev->recv_rc);
    + } else if (vu_dev->vq_irq_vq_map) {
    struct virtqueue *vq;

    virtio_device_for_each_vq((&vu_dev->vdev), vq) {

    \
     
     \ /
      Last update: 2022-06-07 23:42    [W:3.923 / U:0.592 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site