On Tue, Apr 07, 2020 at 04:43:55PM +0200, Martin Pieuchot wrote: > On 07/04/20(Tue) 17:14, Vitaliy Makkoveev wrote: > > As Claudio Jeker noticed, NET_LOCK() can release KERNEL_LOCK(). pppx(4) > > code has some NET_LOCK() dances which make it unsafe. [...] > > The easiest way to fix that is to move if_detach() out of pppx_if_destroy().
Yes, but we are going to move pppx(4) code out from locking. My diff prevents concurent access to pxi_if by pppx_del_session(). Yes pppx_del_session() can grab pxi_if owned by other threads (in the future, after KERNEL_LOCK() will gone), but after refcounters this will be fine and we can push NET_LOCK() deeper. > It generally makes sense to call if_detach() first then free/close the > descriptor of a driver. However some drivers have callbacks and in that > case you might want to teardown those first then call if_detach(). > All the code from pppx_if_destroy() and pppx_add_session() has the wrong ordered netif usage. > if_detach() will require the NET_LOCK() for some time. However > pseudo-driver should start protecting their own data structure with > different locks. >
