On 29/02/2024 08:55, Eric Dumazet wrote:
On Thu, Feb 29, 2024 at 9:04 AM Tasmiya Nalatwad
<tasm...@linux.vnet.ibm.com> wrote:

Greetings,

I have tried the patch provided below. Moving struct to file
"net/core/rtnetlink.c" is not resolving the problem. Please find the
below traces.

--- Traces ---

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:
net/core/rtnetlink.c: 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())
    ^~~~~~~~~~~~~~~~~~~~~
net/core/rtnetlink.c:1059:15: note: in expansion of macro
‘rcu_dereference_rtnl’
          return rcu_dereference_rtnl(dev->dpll_pin);
                 ^~~~~~~~~~~~~~~~~~~~
    CC      crypto/algboss.o
net/core/rtnetlink.c:1063:1: error: control reaches end of non-void
function [-Werror=return-type]
   }
   ^
    CC      crypto/authenc.o
    CC      crypto/authencesn.o
    CC      crypto/af_alg.o
    CC      crypto/algif_hash.o
    CC      crypto/algif_skcipher.o
    CC      crypto/algif_rng.o
    CC      crypto/algif_aead.o
    AR      arch/powerpc/kernel/built-in.a
cc1: some warnings being treated as errors
make[4]: *** [scripts/Makefile.build:243: net/core/rtnetlink.o] Error 1
make[4]: *** Waiting for unfinished jobs....
    CC      lib/kobject_uevent.o
    AR      drivers/net/mdio/built-in.a
    AR      net/802/built-in.a
    AR      drivers/connector/built-in.a
    CC      lib/vsprintf.o
    AR      ipc/built-in.a
    AR      net/nsh/built-in.a
    CC      lib/dynamic_debug.o
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);
    ^~~~~~~~~~~~~~~~~~

On 2/28/24 20:13, Eric Dumazet wrote:
On Wed, Feb 28, 2024 at 3:07 PM Vadim Fedorenko
<vadim.fedore...@linux.dev> wrote:
On 28/02/2024 11:09, Tasmiya Nalatwad wrote:
Greetings,

[revert 0d60d8df6f49] [net/net-next] [6.8-rc5] Build Failure

Reverting below commit fixes the issue

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

--- 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]
    }

Hi, Eric!

Looks like we have to move struct dpll_pin definition to
include/linux/dpll.h to have this fixed, right?

No idea what is wrong. Is it powerpc specific ? Some compiler version ?

netdev_dpll_pin() could be moved to net/core/rtnetlink.c, this is the only user.

OK, it seems netdev_dpll_pin() has to be moved in a place the
structure is known,
because rcu_dereference() needs to know its size.

I do not see other solution than this, otherwise we have to add more
pollution to include/linux/netdevice.h

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 
a9c973b92294bb110cf3cd336485972127b01b58..40797ea80bc6273cae6b7773d0a3e47459a72150
100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2469,7 +2469,7 @@ struct net_device {
         struct devlink_port     *devlink_port;

  #if IS_ENABLED(CONFIG_DPLL)
-       struct dpll_pin __rcu   *dpll_pin;
+       void __rcu *dpll_pin;
  #endif
  #if IS_ENABLED(CONFIG_PAGE_POOL)
         /** @page_pools: page pools created for this netdevice */

I agree, this is the easiest solution.

Reviewed-by: Vadim Fedorenko <vadim.fedor...@linux.dev>

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