Re: [RFC PATCH 0/3] sysfs: allow suicide

From: Eric W. Biederman
Date: Wed Mar 25 2009 - 01:54:37 EST



Interesting.

Fixing a read/writer deadlock by allowing the writers to nest
inside the readers.

My first impression is that it is too clever.

Furthermore I think this is walking around the edges of a more
general problem. How should we serial hotplug and hotunplug
in general. In what context should remove methods run in.

My impression is that we have a huge hole in our infrastructure
for hotplug drivers. Problems like how do we get a user space
context for the code to run in and how do we handle
multiple hotplug actions for overlapping device trees from
stomping on each other.

My hypothesis is once we solve this for the general case of
device hotplug and removal we won't need special support from
sysfs. At least not in the suicidal way.

We still have very weird cases such as the lock inversion that
we have today between rtnl_lock and active reference count,
coming from the networking code.

Eric
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