Messages in this thread | | | From | Kay Sievers <> | Date | Wed, 12 Aug 2009 16:32:48 +0200 | Subject | Re: Event notification when sysfs attribute changes |
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On Wed, Aug 12, 2009 at 16:26, Rick L. Vinyard, Jr.<rvinyard@cs.nmsu.edu> wrote: > I'd like to allow userspace applications to track and display state > changes (without polling) in a driver that exports attributes via sysfs. > > What is the best way to notify userspace applications when a sysfs > exported attribute changes? > > In particular I wanted to drive the notification in the *_store() function > of the sysfs attribute. > > Also, ideally, the mechanism would allow multiple userspace applications > to hook into the notification.
There is nothing like this which works out-of-the-box. It needs kernel support for every attribute that should be able to do that. Then poll() can block until the kernel signifies a change, and return with ERR, so the listener wakes up and can read the attribute again.
Kay
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