On Sun, Apr 07, 2019 at 04:41:36PM -0400, Mathieu Desnoyers wrote: > > ----- On Apr 7, 2019, at 3:32 PM, Joel Fernandes, Google > j...@joelfernandes.org wrote: > > > On Sun, Apr 07, 2019 at 03:26:16PM -0400, Mathieu Desnoyers wrote: > >> ----- On Apr 7, 2019, at 9:59 AM, paulmck paul...@linux.ibm.com wrote: > >> > >> > On Sun, Apr 07, 2019 at 06:39:41AM -0700, Paul E. McKenney wrote: > >> >> On Sat, Apr 06, 2019 at 07:06:13PM -0400, Joel Fernandes wrote: > >> > > >> > [ . . . ] > >> > > >> >> > > diff --git a/include/asm-generic/vmlinux.lds.h > >> >> > > b/include/asm-generic/vmlinux.lds.h > >> >> > > index f8f6f04c4453..c2d919a1566e 100644 > >> >> > > --- a/include/asm-generic/vmlinux.lds.h > >> >> > > +++ b/include/asm-generic/vmlinux.lds.h > >> >> > > @@ -338,6 +338,10 @@ > >> >> > > KEEP(*(__tracepoints_ptrs)) /* Tracepoints: pointer > >> >> > > array */ \ > >> >> > > __stop___tracepoints_ptrs = .; > >> >> > > \ > >> >> > > *(__tracepoints_strings)/* Tracepoints: strings */ > >> >> > > \ > >> >> > > + . = ALIGN(8); > >> >> > > \ > >> >> > > + __start___srcu_struct = .; > >> >> > > \ > >> >> > > + *(___srcu_struct_ptrs) > >> >> > > \ > >> >> > > + __end___srcu_struct = .; > >> >> > > \ > >> >> > > } > >> >> > > \ > >> >> > > >> >> > This vmlinux linker modification is not needed. I tested without it > >> >> > and srcu > >> >> > torture works fine with rcutorture built as a module. Putting further > >> >> > prints > >> >> > in kernel/module.c verified that the kernel is able to find the srcu > >> >> > structs > >> >> > just fine. You could squash the below patch into this one or apply it > >> >> > on top > >> >> > of the dev branch. > >> >> > >> >> Good point, given that otherwise FORTRAN named common blocks would not > >> >> work. > >> >> > >> >> But isn't one advantage of leaving that stuff in the RO_DATA_SECTION() > >> >> macro that it can be mapped read-only? Or am I suffering from excessive > >> >> optimism? > >> > > >> > And to answer the other question, in the case where I am suffering from > >> > excessive optimism, it should be a separate commit. Please see below > >> > for the updated original commit thus far. > >> > > >> > And may I have your Tested-by? > >> > >> Just to confirm: does the cleanup performed in the modules going > >> notifier end up acting as a barrier first before freeing the memory ? > >> If not, is it explicitly stated that a barrier must be issued before > >> module unload ? > >> > > > > You mean rcu_barrier? It is mentioned in the documentation that this is the > > responsibility of the module writer to prevent delays for all modules. > > It's a srcu barrier yes. Considering it would be a barrier specific to the > srcu domain within that module, I don't see how it would cause delays for > "all" modules if we implicitly issue the barrier on module unload. What > am I missing ?
Yes you are right. I thought of this after I just sent my email. I think it makes sense for srcu case to do and could avoid a class of bugs. thanks! > > Thanks, > > Mathieu > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm
