Re: [PATCH 4/4] rcu: Switch to using free() instead of kfree()

[kbuild test robot <lkp@intel.com>]

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Hi Matthew,

I love your patch! Perhaps something to improve:

[auto build test WARNING on rcu/rcu/next]
[also build test WARNING on v4.16-rc6 next-20180323]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Matthew-Wilcox/Add-free-function/20180324-140756
base:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/next
config: x86_64-randconfig-x016-201811 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

   In file included from include/linux/kernel.h:10:0,
                    from kernel/rcu/tree.c:31:
   kernel/rcu/tree_plugin.h: In function '__call_rcu_nocb':
   kernel/rcu/tree_plugin.h:2020:6: error: implicit declaration of function '__is_kfree_rcu_offset'; did you mean '__is_free_rcu_offset'? [-Werror=implicit-function-declaration]
     if (__is_kfree_rcu_offset((unsigned long)rhp->func))
         ^
   include/linux/compiler.h:58:30: note: in definition of macro '__trace_if'
     if (__builtin_constant_p(!!(cond)) ? !!(cond) :   \
                                 ^~~~
>> kernel/rcu/tree_plugin.h:2020:2: note: in expansion of macro 'if'
     if (__is_kfree_rcu_offset((unsigned long)rhp->func))
     ^~
   In file included from kernel/rcu/tree.c:4210:0:
   kernel/rcu/tree_plugin.h:2021:3: error: implicit declaration of function 'trace_rcu_kfree_callback'; did you mean 'trace_rcu_free_callback'? [-Werror=implicit-function-declaration]
      trace_rcu_kfree_callback(rdp->rsp->name, rhp,
      ^~~~~~~~~~~~~~~~~~~~~~~~
      trace_rcu_free_callback
   cc1: some warnings being treated as errors

vim +/if +2020 kernel/rcu/tree_plugin.h

3fbfbf7a3b kernel/rcutree_plugin.h  Paul E. McKenney    2012-08-19  2016  
d1e43fa5f8 kernel/rcutree_plugin.h  Frederic Weisbecker 2013-03-26  2017  	if (!rcu_is_nocb_cpu(rdp->cpu))
c271d3a957 kernel/rcu/tree_plugin.h Pranith Kumar       2014-07-08  2018  		return false;
96d3fd0d31 kernel/rcu/tree_plugin.h Paul E. McKenney    2013-10-04  2019  	__call_rcu_nocb_enqueue(rdp, rhp, &rhp->next, 1, lazy, flags);
21e7a60874 kernel/rcutree_plugin.h  Paul E. McKenney    2013-02-09 @2020  	if (__is_kfree_rcu_offset((unsigned long)rhp->func))
21e7a60874 kernel/rcutree_plugin.h  Paul E. McKenney    2013-02-09  2021  		trace_rcu_kfree_callback(rdp->rsp->name, rhp,
21e7a60874 kernel/rcutree_plugin.h  Paul E. McKenney    2013-02-09  2022  					 (unsigned long)rhp->func,
756cbf6bef kernel/rcutree_plugin.h  Paul E. McKenney    2013-08-15  2023  					 -atomic_long_read(&rdp->nocb_q_count_lazy),
756cbf6bef kernel/rcutree_plugin.h  Paul E. McKenney    2013-08-15  2024  					 -atomic_long_read(&rdp->nocb_q_count));
21e7a60874 kernel/rcutree_plugin.h  Paul E. McKenney    2013-02-09  2025  	else
21e7a60874 kernel/rcutree_plugin.h  Paul E. McKenney    2013-02-09  2026  		trace_rcu_callback(rdp->rsp->name, rhp,
756cbf6bef kernel/rcutree_plugin.h  Paul E. McKenney    2013-08-15  2027  				   -atomic_long_read(&rdp->nocb_q_count_lazy),
756cbf6bef kernel/rcutree_plugin.h  Paul E. McKenney    2013-08-15  2028  				   -atomic_long_read(&rdp->nocb_q_count));
1772947bd0 kernel/rcu/tree_plugin.h Paul E. McKenney    2014-08-12  2029  
1772947bd0 kernel/rcu/tree_plugin.h Paul E. McKenney    2014-08-12  2030  	/*
1772947bd0 kernel/rcu/tree_plugin.h Paul E. McKenney    2014-08-12  2031  	 * If called from an extended quiescent state with interrupts
1772947bd0 kernel/rcu/tree_plugin.h Paul E. McKenney    2014-08-12  2032  	 * disabled, invoke the RCU core in order to allow the idle-entry
1772947bd0 kernel/rcu/tree_plugin.h Paul E. McKenney    2014-08-12  2033  	 * deferred-wakeup check to function.
1772947bd0 kernel/rcu/tree_plugin.h Paul E. McKenney    2014-08-12  2034  	 */
1772947bd0 kernel/rcu/tree_plugin.h Paul E. McKenney    2014-08-12  2035  	if (irqs_disabled_flags(flags) &&
1772947bd0 kernel/rcu/tree_plugin.h Paul E. McKenney    2014-08-12  2036  	    !rcu_is_watching() &&
1772947bd0 kernel/rcu/tree_plugin.h Paul E. McKenney    2014-08-12  2037  	    cpu_online(smp_processor_id()))
1772947bd0 kernel/rcu/tree_plugin.h Paul E. McKenney    2014-08-12  2038  		invoke_rcu_core();
1772947bd0 kernel/rcu/tree_plugin.h Paul E. McKenney    2014-08-12  2039  
c271d3a957 kernel/rcu/tree_plugin.h Pranith Kumar       2014-07-08  2040  	return true;
3fbfbf7a3b kernel/rcutree_plugin.h  Paul E. McKenney    2012-08-19  2041  }
3fbfbf7a3b kernel/rcutree_plugin.h  Paul E. McKenney    2012-08-19  2042  

:::::: The code at line 2020 was first introduced by commit
:::::: 21e7a6087480451804124cee27c0a7d0a7de1564 rcu: Add event tracing for no-CBs CPUs' callback registration

:::::: TO: Paul E. McKenney <paul.mckenney@linaro.org>
:::::: CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

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