[rcu:rcu/next 78/83] kernel/rcu/tasks.h:740:8: error: type defaults to 'int' in declaration of 'DEFINE_IRQ_WORK'

[kbuild test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/next
head:   72f26c3be409e0ccd52a48e7f5ffbdbb5cd0a960
commit: f7f9f5b97a87a31d90fe254f6e685b67e0b378a9 [78/83] rcu-tasks: Allow rcu_read_unlock_trace() under scheduler locks
config: m68k-allmodconfig (attached as .config)
compiler: m68k-linux-gcc (GCC) 9.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git checkout f7f9f5b97a87a31d90fe254f6e685b67e0b378a9
        # save the attached .config to linux build tree
        GCC_VERSION=9.2.0 make.cross ARCH=m68k 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@xxxxxxxxx>

All error/warnings (new ones prefixed by >>):

   In file included from kernel/rcu/update.c:562:
>> kernel/rcu/tasks.h:736:39: warning: 'struct irq_work' declared inside parameter list will not be visible outside of this definition or declaration
     736 | static void rcu_read_unlock_iw(struct irq_work *iwp)
         |                                       ^~~~~~~~
>> kernel/rcu/tasks.h:740:8: error: type defaults to 'int' in declaration of 'DEFINE_IRQ_WORK' [-Werror=implicit-int]
     740 | static DEFINE_IRQ_WORK(rcu_tasks_trace_iw, rcu_read_unlock_iw);
         |        ^~~~~~~~~~~~~~~
>> kernel/rcu/tasks.h:740:1: warning: parameter names (without types) in function declaration
     740 | static DEFINE_IRQ_WORK(rcu_tasks_trace_iw, rcu_read_unlock_iw);
         | ^~~~~~
   kernel/rcu/tasks.h: In function 'rcu_read_unlock_trace_special':
>> kernel/rcu/tasks.h:751:3: error: implicit declaration of function 'irq_work_queue'; did you mean 'drain_workqueue'? [-Werror=implicit-function-declaration]
     751 |   irq_work_queue(&rcu_tasks_trace_iw);
         |   ^~~~~~~~~~~~~~
         |   drain_workqueue
>> kernel/rcu/tasks.h:751:19: error: 'rcu_tasks_trace_iw' undeclared (first use in this function); did you mean 'rcu_tasks_trace_qs'?
     751 |   irq_work_queue(&rcu_tasks_trace_iw);
         |                   ^~~~~~~~~~~~~~~~~~
         |                   rcu_tasks_trace_qs
   kernel/rcu/tasks.h:751:19: note: each undeclared identifier is reported only once for each function it appears in
   kernel/rcu/update.c: At top level:
   kernel/rcu/tasks.h:740:8: warning: 'DEFINE_IRQ_WORK' declared 'static' but never defined [-Wunused-function]
     740 | static DEFINE_IRQ_WORK(rcu_tasks_trace_iw, rcu_read_unlock_iw);
         |        ^~~~~~~~~~~~~~~
   kernel/rcu/tasks.h:736:13: warning: 'rcu_read_unlock_iw' defined but not used [-Wunused-function]
     736 | static void rcu_read_unlock_iw(struct irq_work *iwp)
         |             ^~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors

vim +740 kernel/rcu/tasks.h

   727	
   728	void call_rcu_tasks_trace(struct rcu_head *rhp, rcu_callback_t func);
   729	DEFINE_RCU_TASKS(rcu_tasks_trace, rcu_tasks_wait_gp, call_rcu_tasks_trace,
   730			 "RCU Tasks Trace");
   731	
   732	/*
   733	 * This irq_work handler allows rcu_read_unlock_trace() to be invoked
   734	 * while the scheduler locks are held.
   735	 */
 > 736	static void rcu_read_unlock_iw(struct irq_work *iwp)
   737	{
   738		wake_up(&trc_wait);
   739	}
 > 740	static DEFINE_IRQ_WORK(rcu_tasks_trace_iw, rcu_read_unlock_iw);
   741	
   742	/* If we are the last reader, wake up the grace-period kthread. */
   743	void rcu_read_unlock_trace_special(struct task_struct *t, int nesting)
   744	{
   745		if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB) &&
   746		    t->trc_reader_special.b.need_mb)
   747			smp_mb(); // Pairs with update-side barriers.
   748		WRITE_ONCE(t->trc_reader_nesting, nesting);
   749		WRITE_ONCE(t->trc_reader_special.b.need_qs, false);
   750		if (atomic_dec_and_test(&trc_n_readers_need_end))
 > 751			irq_work_queue(&rcu_tasks_trace_iw);
   752	}
   753	EXPORT_SYMBOL_GPL(rcu_read_unlock_trace_special);
   754	

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