linux-kernel - Re: [PATCH-tip v6 18/22] TP-futex: Group readers together in wait queue

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Message-ID: <201703241639.k8SjGKnN%fengguang.wu@intel.com>
Date:   Fri, 24 Mar 2017 16:19:03 +0800
From:   kbuild test robot <lkp@...el.com>
To:     Waiman Long <longman@...hat.com>
Cc:     kbuild-all@...org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Jonathan Corbet <corbet@....net>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Davidlohr Bueso <dave@...olabs.net>,
        Mike Galbraith <umgwanakikbuti@...il.com>,
        Scott J Norton <scott.norton@....com>,
        Waiman Long <longman@...hat.com>
Subject: Re: [PATCH-tip v6 18/22] TP-futex: Group readers together in wait
 queue

Hi Waiman,

[auto build test ERROR on next-20170323]
[also build test ERROR on v4.11-rc3]
[cannot apply to linus/master linux/master tip/perf/core v4.9-rc8 v4.9-rc7 v4.9-rc6]
[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/Waiman-Long/perf-bench-New-microbenchmark-for-userspace-mutex-performance/20170324-135043
config: m32r-usrv_defconfig (attached as .config)
compiler: m32r-linux-gcc (GCC) 6.2.0
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=m32r 

All errors (new ones prefixed by >>):

   kernel/built-in.o: In function `futex_spin_on_reader':
>> kernel/futex.c:4003: undefined reference to `osq_lock'
   kernel/futex.c:4003:(.text+0x5cc98): relocation truncated to fit: R_M32R_26_PCREL_RELA against undefined symbol `osq_lock'
>> kernel/futex.c:4040: undefined reference to `osq_unlock'
   kernel/futex.c:4040:(.text+0x5cd2c): relocation truncated to fit: R_M32R_26_PCREL_RELA against undefined symbol `osq_unlock'
   kernel/futex.c:4033: undefined reference to `osq_unlock'
   kernel/futex.c:4033:(.text+0x5d0d4): relocation truncated to fit: R_M32R_26_PCREL_RELA against undefined symbol `osq_unlock'

vim +4003 kernel/futex.c

  3997		first_reader = READ_ONCE(state->first_reader);
  3998		if (!first_reader)
  3999			first_reader = cmpxchg(&state->first_reader, NULL, current);
  4000		if (!first_reader)
  4001			goto out;	/* Became the first reader */
  4002	
> 4003		if (!osq_lock(&state->reader_osq))
  4004			goto reschedule;
  4005	
  4006		rcu_read_lock();
  4007		for (;;) {
  4008			u32 uval;
  4009	
  4010			if (!state->handoff_pid && (prefer_reader ||
  4011			   (first_reader == READ_ONCE(state->mutex_owner)))) {
  4012				ret = futex_trylock_preempt_disabled(uaddr,
  4013							FUTEX_SHARED, &uval, false);
  4014				/*
  4015				 * Return if lock acquired or an error happened
  4016				 */
  4017				if (ret)
  4018					break;
  4019			}
  4020	
  4021			/*
  4022			 * Reread the first reader value again.
  4023			 */
  4024			first_reader = READ_ONCE(state->first_reader);
  4025			if (!first_reader)
  4026				first_reader = cmpxchg(&state->first_reader, NULL,
  4027							current);
  4028			if (!first_reader || !first_reader->on_cpu)
  4029				break;
  4030	
  4031			if (need_resched()) {
  4032				rcu_read_unlock();
  4033				osq_unlock(&state->reader_osq);
  4034				goto reschedule;
  4035			}
  4036	
  4037			cpu_relax();
  4038		}
  4039		rcu_read_unlock();
> 4040		osq_unlock(&state->reader_osq);
  4041	out:
  4042		*pfirst = first_reader;
  4043		preempt_enable();

---
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