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authorCornelia Huck <cohuck@redhat.com>2019-01-31 15:53:14 +0300
committerMichael S. Tsirkin <mst@redhat.com>2019-03-06 19:19:57 +0300
commitab7a2375fb8e83f8744c34442f476fa5a9df5e35 (patch)
tree58698720fc0a7a79f4fdefaae195aabf57a83dba /drivers/virtio
parent971bedca26e037ee961e090c84c2640563836d3e (diff)
downloadlinux-ab7a2375fb8e83f8744c34442f476fa5a9df5e35.tar.xz
virtio: hint if callbacks surprisingly might sleep
A virtio transport is free to implement some of the callbacks in virtio_config_ops in a matter that they cannot be called from atomic context (e.g. virtio-ccw, which maps a lot of the callbacks to channel I/O, which is an inherently asynchronous mechanism). This can be very surprising for developers using the much more common virtio-pci transport, just to find out that things break when used on s390. The documentation for virtio_config_ops now contains a comment explaining this, but it makes sense to add a might_sleep() annotation to various wrapper functions in the virtio core to avoid surprises later. Note that annotations are NOT added to two classes of calls: - direct calls from device drivers (all current callers should be fine, however) - calls which clearly won't be made from atomic context (such as those ultimately coming in via the driver core) Signed-off-by: Cornelia Huck <cohuck@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/virtio')
-rw-r--r--drivers/virtio/virtio.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 59e36ef4920f..98b30f54342c 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -161,6 +161,7 @@ EXPORT_SYMBOL_GPL(virtio_config_enable);
void virtio_add_status(struct virtio_device *dev, unsigned int status)
{
+ might_sleep();
dev->config->set_status(dev, dev->config->get_status(dev) | status);
}
EXPORT_SYMBOL_GPL(virtio_add_status);
@@ -170,6 +171,7 @@ int virtio_finalize_features(struct virtio_device *dev)
int ret = dev->config->finalize_features(dev);
unsigned status;
+ might_sleep();
if (ret)
return ret;