On Wed, May 18 2022, Jason Wang <jasowang@xxxxxxxxxx> wrote:
> This patch tries to implement the synchronize_cbs() for ccw. For the
> vring_interrupt() that is called via virtio_airq_handler(), the
> synchronization is simply done via the airq_info's lock. For the
> vring_interrupt() that is called via virtio_ccw_int_handler(), a per
> device rwlock is introduced ans used in the synchronization method.
s/ans/and/
>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
> Cc: Marc Zyngier <maz@xxxxxxxxxx>
> Cc: Halil Pasic <pasic@xxxxxxxxxxxxx>
> Cc: Cornelia Huck <cohuck@xxxxxxxxxx>
> Cc: Vineeth Vijayan <vneethv@xxxxxxxxxxxxx>
> Cc: Peter Oberparleiter <oberpar@xxxxxxxxxxxxx>
> Cc: linux-s390@xxxxxxxxxxxxxxx
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> drivers/s390/virtio/virtio_ccw.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
> index d35e7a3f7067..22d36594bcdd 100644
> --- a/drivers/s390/virtio/virtio_ccw.c
> +++ b/drivers/s390/virtio/virtio_ccw.c
> @@ -62,6 +62,7 @@ struct virtio_ccw_device {
> unsigned int revision; /* Transport revision */
> wait_queue_head_t wait_q;
> spinlock_t lock;
> + rwlock_t irq_lock;
> struct mutex io_lock; /* Serializes I/O requests */
> struct list_head virtqueues;
> bool is_thinint;
> @@ -984,6 +985,27 @@ static const char *virtio_ccw_bus_name(struct virtio_device *vdev)
> return dev_name(&vcdev->cdev->dev);
> }
>
> +static void virtio_ccw_synchronize_cbs(struct virtio_device *vdev)
> +{
> + struct virtio_ccw_device *vcdev = to_vc_device(vdev);
> + struct airq_info *info = vcdev->airq_info;
> +
> + if (info) {
> + /*
> + * Synchronize with the vring_interrupt() with airq indicator
Maybe
/*
* This device uses adapter interrupts: synchronize with
* vring_interrupt() called by virtio_airq_handler() via the indicator
* area lock.
*/
> + */
> + write_lock_irq(&info->lock);
> + write_unlock_irq(&info->lock);
> + } else {
> + /*
> + * Synchronize with the vring_interrupt() called by
> + * virtio_ccw_int_handler().
/*
* This device uses classic interrupts: synchronize with
* vring_interrupt() called by virtio_ccw_int_handler() via the
* per-device irq_lock.
*/
> + */
> + write_lock_irq(&vcdev->irq_lock);
> + write_unlock_irq(&vcdev->irq_lock);
> + }
> +}
> +
> static const struct virtio_config_ops virtio_ccw_config_ops = {
> .get_features = virtio_ccw_get_features,
> .finalize_features = virtio_ccw_finalize_features,
> @@ -995,6 +1017,7 @@ static const struct virtio_config_ops virtio_ccw_config_ops = {
> .find_vqs = virtio_ccw_find_vqs,
> .del_vqs = virtio_ccw_del_vqs,
> .bus_name = virtio_ccw_bus_name,
> + .synchronize_cbs = virtio_ccw_synchronize_cbs,
> };
>
>
> @@ -1106,6 +1129,8 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev,
> vcdev->err = -EIO;
> }
> virtio_ccw_check_activity(vcdev, activity);
> + /* Local interrupt should be disabled at this time */
/* Interrupts are disabled here. */
?
Interrupts enabled here would surely be a bug.
> + read_lock(&vcdev->irq_lock);
> for_each_set_bit(i, indicators(vcdev),
> sizeof(*indicators(vcdev)) * BITS_PER_BYTE) {
> /* The bit clear must happen before the vring kick. */
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