Re: alternate event logging proposal

Tim Hockin
2002-09-24T23:34:14Z

Jeff Garzik wrote:
> Brad Hards wrote:
>
>> I liked the /sbin/hotplug arrangement (aka call_usermode_helper). In
>> fact, my plan was to add the call_usermode_helper call to the
>> netif_carrier_[on,off] functions. Unfortuantely, I've been to too many
>> of Rusty's talks, and know that calling a function that is only safe
>> in user context is unlikely to be a good idea in
>> netif_carrier_[on,off], which are more than likely running in
>> interrupt context.
>
>
>
> You really want something where a userspace app can sleep on an fd, to
> be awakened when link changes (or some other interesting event occurs)

I tend to agree - I like either of the models:

a bunch of little single-value files that can be polled and read

or

a single device_event file that a daemon reads and dispatches events (I
like this one because the daemon is already written, just poorly named -
acpid)

For things like netif_carrier, poll() is probably best - the DHCP client
can be fully self contained, and not need an eventd to alert it to a
signal change. Of course, acpid does support UNIX socket connections
from apps like DHCP....

--
Tim Hockin
Systems Software Engineer
Sun Microsystems, Linux Kernel Engineering
thockin@sun.com