xenbus_watch_pathfmt(9)

💖 xenbus_watch_pathfmt 💖

🎀 NAME 🎀

okay so this is the xenbus_watch_pathfmt(9) Kernel API Manual page, bestie, and xenbus_watch_pathfmt means: register a watch on a sprintf-formatted path. iconic.

🦋 SYNOPSIS 🦋

int xenbus_watch_pathfmt (struct xenbus_device *dev , struct
       xenbus_watch *watch , bool (*will_handle)(struct xenbus_watch *, const
       char *, const char *) , void (*callback)(struct xenbus_watch *, const
       char *, const char *) , const char *pathfmt , ... );

🌸 ARGUMENTS 🌸

• dev — xenbus device, your main character device.
• watch — watch to register; this is the storage spot.
• will_handle — events queuing determine callback, aka the function that decides whether each event needs to be queued.
• callback — callback to register.
• pathfmt — format of path to watch.
• ... — variable arguments. feed the format, bestie.

💅 DESCRIPTION 💅

okay so here's the tea: you register a watch on the given path. you use the given xenbus_watch structure for storage, the will_handle function as the callback to determine if each event need to be queued, and the given callback function as the callback. slay.

On success, the watched path (path/path2) will be saved as watch->node, and becomes the caller's to kfree. so yes, that memory is now yours to free, bestie 🫶.

🚨 On error, watch->node will be NULL, so the caller has nothing to free. the device will switch to XenbusStateClosing, and the error will be saved in the store. no cap, that's the whole error vibe.

⭐ RETURN ⭐

0 on success or -errno on error. short and iconic 💅.

🔥 SEE ALSO 🔥

Kernel file ./drivers/xen/xenbus/xenbus_client.c is over here doing its thing, and these are the related manual besties:

• xenbus_watch_path(9)
• xenbus_switch_state(9)
• xenbus_dev_error(9)
• xenbus_dev_fatal(9)
• xenbus_map_ring_valloc(9)
• xenbus_unmap_ring(9)
• xenbus_unmap_ring_vfree(9)
• xenbus_read_driver_state(9)

catch you in ./drivers/xen/xenbus, dated October 2026, bestie — this was xenbus_watch_pathfmt(9), mwah 💋✨