Using the Linux sysfs_notify call

Question

I am trying to communicate asynchronously between a kernel driver and a user-space program (I know there are lots of questions here that ask for similar information, but I c

Answer 1

The blocking poll is from the user side. User code can simply tell the kernel which attributes it's interested in, then block in a poll() until one of them has changed.

The sysfs_notify() is a kernel-side call that releases the user-space poll(). After you adjust your kernel attribute value, just call sysfs_notify() to allow any user-space applications to respond to their outstanding poll().

Think of the poll() as "subscribing" to notices of a change in an attribute of interest, and sysfs_notify() as "publishing" the change to any subscribers.