tree 7826e827b0719f48388c5354ca7f98fbeb10844f
parent fc82511201853a33d5e5e59149897843ef0e28a0
author Ohad Ben-Cohen <ohad@wizery.com> 1338966565 +0300
committer chrmhoffmann <chrmhoffmann@gmail.com> 1586074533 +0200

rpmsg: avoid premature deallocation of endpoints

commit 5a081caa0414b9bbb82c17ffab9d6fe66edbb72f upstream.

When an inbound message arrives, the rpmsg core looks up its
associated endpoint and invokes the registered callback.

If a message arrives while its endpoint is being removed (because
the rpmsg driver was removed, or a recovery of a remote processor
has kicked in) we must ensure atomicity, i.e.:

- Either the ept is removed before it is found

or

- The ept is found but will not be freed until the callback returns

This is achieved by maintaining a per-ept reference count, which,
when drops to zero, will trigger deallocation of the ept.

With this in hand, it is now forbidden to directly deallocate
epts once they have been added to the endpoints idr.

Reported-by: Fernando Guzman Lugo <fernando.lugo@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>