drbd: use list_first_entry_or_null in first_peer_device/first_connection (ec4a3407) · Commits · 戴 / test

If there are no peer_devices or connections, I'd rather have NULL than some "arbitrary" address pretending to point to a struct. Helps to avoid hard to debug symptoms, in case we ever try to use and dereference a drbd_connection or drbd_peer_device where we in fact don't have any connection at all. Signed-off-by:

Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by:

Lars Ellenberg <lars.ellenberg@linbit.com> Signed-off-by:

Jens Axboe <axboe@fb.com>

drivers/block/drbd/drbd_int.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -853,7 +853,7 @@ static inline struct drbd_device *minor_to_device(unsigned int minor)

		static inline struct drbd_peer_device first_peer_device(struct drbd_device device)
		{
		return list_first_entry(&device->peer_devices, struct drbd_peer_device, peer_devices);
		return list_first_entry_or_null(&device->peer_devices, struct drbd_peer_device, peer_devices);
		}

		#define for_each_resource(resource, _resources) \
		@@ -2222,7 +2222,7 @@ static inline void drbd_md_flush(struct drbd_device *device)

		static inline struct drbd_connection first_connection(struct drbd_resource resource)
		{
		return list_first_entry(&resource->connections,
		return list_first_entry_or_null(&resource->connections,
		struct drbd_connection, connections);
		}

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