[netdev] Build failure on powerpc

[Tasmiya Nalatwad]

Greetings,

[netdev] Build failure on powerpc
latest netdev 6.8.0-rc5-auto-g1ce7d306ea63 fails to build on powerpc 
below traces

--- Traces---

./include/linux/dpll.h: In function ‘netdev_dpll_pin’:
./include/linux/rcupdate.h:439:9: error: dereferencing pointer to 
incomplete type ‘struct dpll_pin’
   typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \
          ^
./include/linux/rcupdate.h:587:2: note: in expansion of macro 
‘__rcu_dereference_check’
   __rcu_dereference_check((p), __UNIQUE_ID(rcu), \
   ^~~~~~~~~~~~~~~~~~~~~~~
./include/linux/rtnetlink.h:70:2: note: in expansion of macro 
‘rcu_dereference_check’
   rcu_dereference_check(p, lockdep_rtnl_is_held())
   ^~~~~~~~~~~~~~~~~~~~~
./include/linux/dpll.h:175:9: note: in expansion of macro 
‘rcu_dereference_rtnl’
   return rcu_dereference_rtnl(dev->dpll_pin);
          ^~~~~~~~~~~~~~~~~~~~
make[4]: *** [scripts/Makefile.build:243: drivers/dpll/dpll_core.o] Error 1
make[4]: *** Waiting for unfinished jobs....
   AR      net/mpls/built-in.a
   AR      net/l3mdev/built-in.a
In file included from ./include/linux/rbtree.h:24,
                  from ./include/linux/mm_types.h:11,
                  from ./include/linux/mmzone.h:22,
                  from ./include/linux/gfp.h:7,
                  from ./include/linux/umh.h:4,
                  from ./include/linux/kmod.h:9,
                  from ./include/linux/module.h:17,
                  from drivers/dpll/dpll_netlink.c:9:
./include/linux/dpll.h: In function ‘netdev_dpll_pin’:
./include/linux/rcupdate.h:439:9: error: dereferencing pointer to 
incomplete type ‘struct dpll_pin’
   typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \
          ^
./include/linux/rcupdate.h:587:2: note: in expansion of macro 
‘__rcu_dereference_check’
   __rcu_dereference_check((p), __UNIQUE_ID(rcu), \
   ^~~~~~~~~~~~~~~~~~~~~~~
./include/linux/rtnetlink.h:70:2: note: in expansion of macro 
‘rcu_dereference_check’
   rcu_dereference_check(p, lockdep_rtnl_is_held())
   ^~~~~~~~~~~~~~~~~~~~~
./include/linux/dpll.h:175:9: note: in expansion of macro 
‘rcu_dereference_rtnl’
   return rcu_dereference_rtnl(dev->dpll_pin);
          ^~~~~~~~~~~~~~~~~~~~
make[4]: *** [scripts/Makefile.build:243: drivers/dpll/dpll_netlink.o] 
Error 1
make[3]: *** [scripts/Makefile.build:481: drivers/dpll] Error 2
make[3]: *** Waiting for unfinished jobs....
In file included from ./arch/powerpc/include/generated/asm/rwonce.h:1,
                  from ./include/linux/compiler.h:251,
                  from ./include/linux/instrumented.h:10,
                  from ./include/linux/uaccess.h:6,
                  from net/core/dev.c:71:
net/core/dev.c: In function ‘netdev_dpll_pin_assign’:
./include/linux/rcupdate.h:462:36: error: dereferencing pointer to 
incomplete type ‘struct dpll_pin’
  #define RCU_INITIALIZER(v) (typeof(*(v)) __force __rcu *)(v)
                                     ^~~~
./include/asm-generic/rwonce.h:55:33: note: in definition of macro 
‘__WRITE_ONCE’
   *(volatile typeof(x) *)&(x) = (val);    \
                                  ^~~
./arch/powerpc/include/asm/barrier.h:76:2: note: in expansion of macro 
‘WRITE_ONCE’
   WRITE_ONCE(*p, v);      \
   ^~~~~~~~~~
./include/asm-generic/barrier.h:172:55: note: in expansion of macro 
‘__smp_store_release’
  #define smp_store_release(p, v) do { kcsan_release(); 
__smp_store_release(p, v); } while (0)
^~~~~~~~~~~~~~~~~~~
./include/linux/rcupdate.h:503:3: note: in expansion of macro 
‘smp_store_release’
    smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \
    ^~~~~~~~~~~~~~~~~
./include/linux/rcupdate.h:503:25: note: in expansion of macro 
‘RCU_INITIALIZER’
    smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \
                          ^~~~~~~~~~~~~~~
net/core/dev.c:9081:2: note: in expansion of macro ‘rcu_assign_pointer’
   rcu_assign_pointer(dev->dpll_pin, dpll_pin);
   ^~~~~~~~~~~~~~~~~~
make[4]: *** [scripts/Makefile.build:243: net/core/dev.o] Error 1
make[4]: *** Waiting for unfinished jobs....
   AR      drivers/net/ethernet/built-in.a
   AR      drivers/net/built-in.a
   AR      net/dcb/built-in.a
   AR      net/netlabel/built-in.a
   AR      net/strparser/built-in.a
   AR      net/handshake/built-in.a
   GEN     lib/test_fortify.log
   AR      net/8021q/built-in.a
   AR      net/nsh/built-in.a
   AR      net/unix/built-in.a
   CC      lib/string.o
   AR      net/packet/built-in.a
   AR      net/switchdev/built-in.a
   AR      lib/lib.a
   AR      net/mptcp/built-in.a
   AR      net/devlink/built-in.a
In file included from ./include/linux/rbtree.h:24,
                  from ./include/linux/mm_types.h:11,
                  from ./include/linux/mmzone.h:22,
                  from ./include/linux/gfp.h:7,
                  from ./include/linux/umh.h:4,
                  from ./include/linux/kmod.h:9,
                  from ./include/linux/module.h:17,
                  from net/core/rtnetlink.c:17:
./include/linux/dpll.h: In function ‘netdev_dpll_pin’:
./include/linux/rcupdate.h:439:9: error: dereferencing pointer to 
incomplete type ‘struct dpll_pin’
   typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \
          ^
./include/linux/rcupdate.h:587:2: note: in expansion of macro 
‘__rcu_dereference_check’
   __rcu_dereference_check((p), __UNIQUE_ID(rcu), \
   ^~~~~~~~~~~~~~~~~~~~~~~
./include/linux/rtnetlink.h:70:2: note: in expansion of macro 
‘rcu_dereference_check’
   rcu_dereference_check(p, lockdep_rtnl_is_held())
   ^~~~~~~~~~~~~~~~~~~~~
./include/linux/dpll.h:175:9: note: in expansion of macro 
‘rcu_dereference_rtnl’
   return rcu_dereference_rtnl(dev->dpll_pin);
          ^~~~~~~~~~~~~~~~~~~~
In file included from net/core/rtnetlink.c:60:
./include/linux/dpll.h:179:1: error: control reaches end of non-void 
function [-Werror=return-type]
  }


Reverting the below commit fixes the problem

commit 0d60d8df6f493bb46bf5db40d39dd60a1bafdd4e
     dpll: rely on rcu for netdev_dpll_pin()

-- 
Regards,
Tasmiya Nalatwad
IBM Linux Technology Center