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path: root/drivers/firmware/arm_scmi/virtio.c
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Diffstat (limited to 'drivers/firmware/arm_scmi/virtio.c')
-rw-r--r--drivers/firmware/arm_scmi/virtio.c44
1 files changed, 31 insertions, 13 deletions
diff --git a/drivers/firmware/arm_scmi/virtio.c b/drivers/firmware/arm_scmi/virtio.c
index 224577f86928..11e8efb71375 100644
--- a/drivers/firmware/arm_scmi/virtio.c
+++ b/drivers/firmware/arm_scmi/virtio.c
@@ -110,18 +110,16 @@ static void scmi_finalize_message(struct scmi_vio_channel *vioch,
if (vioch->is_rx) {
scmi_vio_feed_vq_rx(vioch, msg);
} else {
- unsigned long flags;
-
- spin_lock_irqsave(&vioch->lock, flags);
+ /* Here IRQs are assumed to be already disabled by the caller */
+ spin_lock(&vioch->lock);
list_add(&msg->list, &vioch->free_list);
- spin_unlock_irqrestore(&vioch->lock, flags);
+ spin_unlock(&vioch->lock);
}
}
static void scmi_vio_complete_cb(struct virtqueue *vqueue)
{
unsigned long ready_flags;
- unsigned long flags;
unsigned int length;
struct scmi_vio_channel *vioch;
struct scmi_vio_msg *msg;
@@ -140,7 +138,8 @@ static void scmi_vio_complete_cb(struct virtqueue *vqueue)
goto unlock_ready_out;
}
- spin_lock_irqsave(&vioch->lock, flags);
+ /* IRQs already disabled here no need to irqsave */
+ spin_lock(&vioch->lock);
if (cb_enabled) {
virtqueue_disable_cb(vqueue);
cb_enabled = false;
@@ -151,7 +150,7 @@ static void scmi_vio_complete_cb(struct virtqueue *vqueue)
goto unlock_out;
cb_enabled = true;
}
- spin_unlock_irqrestore(&vioch->lock, flags);
+ spin_unlock(&vioch->lock);
if (msg) {
msg->rx_len = length;
@@ -161,11 +160,18 @@ static void scmi_vio_complete_cb(struct virtqueue *vqueue)
scmi_finalize_message(vioch, msg);
}
+ /*
+ * Release ready_lock and re-enable IRQs between loop iterations
+ * to allow virtio_chan_free() to possibly kick in and set the
+ * flag vioch->ready to false even in between processing of
+ * messages, so as to force outstanding messages to be ignored
+ * when system is shutting down.
+ */
spin_unlock_irqrestore(&vioch->ready_lock, ready_flags);
}
unlock_out:
- spin_unlock_irqrestore(&vioch->lock, flags);
+ spin_unlock(&vioch->lock);
unlock_ready_out:
spin_unlock_irqrestore(&vioch->ready_lock, ready_flags);
}
@@ -384,8 +390,11 @@ static int scmi_vio_probe(struct virtio_device *vdev)
struct virtqueue *vqs[VIRTIO_SCMI_VQ_MAX_CNT];
/* Only one SCMI VirtiO device allowed */
- if (scmi_vdev)
- return -EINVAL;
+ if (scmi_vdev) {
+ dev_err(dev,
+ "One SCMI Virtio device was already initialized: only one allowed.\n");
+ return -EBUSY;
+ }
have_vq_rx = scmi_vio_have_vq_rx(vdev);
vq_cnt = have_vq_rx ? VIRTIO_SCMI_VQ_MAX_CNT : 1;
@@ -428,16 +437,25 @@ static int scmi_vio_probe(struct virtio_device *vdev)
}
vdev->priv = channels;
- scmi_vdev = vdev;
+ /* Ensure initialized scmi_vdev is visible */
+ smp_store_mb(scmi_vdev, vdev);
return 0;
}
static void scmi_vio_remove(struct virtio_device *vdev)
{
+ /*
+ * Once we get here, virtio_chan_free() will have already been called by
+ * the SCMI core for any existing channel and, as a consequence, all the
+ * virtio channels will have been already marked NOT ready, causing any
+ * outstanding message on any vqueue to be ignored by complete_cb: now
+ * we can just stop processing buffers and destroy the vqueues.
+ */
vdev->config->reset(vdev);
vdev->config->del_vqs(vdev);
- scmi_vdev = NULL;
+ /* Ensure scmi_vdev is visible as NULL */
+ smp_store_mb(scmi_vdev, NULL);
}
static int scmi_vio_validate(struct virtio_device *vdev)
@@ -476,7 +494,7 @@ static int __init virtio_scmi_init(void)
return register_virtio_driver(&virtio_scmi_driver);
}
-static void __exit virtio_scmi_exit(void)
+static void virtio_scmi_exit(void)
{
unregister_virtio_driver(&virtio_scmi_driver);
}