ftdev: provide a callback to test whether a device can be opened

This is useful to deny opening per-cpu buffers if a CPU is not online.

1 files changed, 5 insertions, 0 deletions

diff --git a/include/litmus/ftdev.h b/include/litmus/ftdev.h
index 8df916d1fc..7697b46166 100644
--- a/include/litmus/ftdev.h
+++ b/include/litmus/ftdev.h
@@ -13,9 +13,13 @@
 
 struct ftdev;
 
+/* return 0 if buffer can be opened, otherwise -$REASON */
+typedef int  (*ftdev_can_open_t)(struct ftdev* dev, unsigned int buf_no);
+/* return 0 on success, otherwise -$REASON */
 typedef int  (*ftdev_alloc_t)(struct ftdev* dev, unsigned int buf_no);
 typedef void (*ftdev_free_t)(struct ftdev* dev, unsigned int buf_no);
 
+
 struct ftdev_event;
 
 struct ftdev_minor {
@@ -33,6 +37,7 @@ struct ftdev {
         unsigned int            minor_cnt;
         ftdev_alloc_t           alloc;
         ftdev_free_t            free;
+        ftdev_can_open_t        can_open;
 };
 
 struct ft_buffer* alloc_ft_buffer(unsigned int count, size_t size);