From ab7a2375fb8e83f8744c34442f476fa5a9df5e35 Mon Sep 17 00:00:00 2001 From: Cornelia Huck Date: Thu, 31 Jan 2019 13:53:14 +0100 Subject: 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 Signed-off-by: Michael S. Tsirkin --- drivers/virtio/virtio.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/virtio') 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; -- cgit v1.2.3-55-g7522