linux-kernel - Re: [PATCH] MCS spinlock: Use smp_cond_load

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Date:	Tue, 12 Apr 2016 16:50:12 -0700
From:	Jason Low <jason.low2@...com>
To:	kbuild test robot <lkp@...el.com>
Cc:	kbuild-all@...org, Peter Zijlstra <peterz@...radead.org>,
	Will Deacon <will.deacon@....com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, mingo@...hat.com,
	paulmck@...ux.vnet.ibm.com, terry.rudd@....com,
	waiman.long@....com, boqun.feng@...il.com, dave@...olabs.net,
	jason.low2@...com
Subject: Re: [PATCH] MCS spinlock: Use smp_cond_load_acquire()

On Tue, 2016-04-12 at 16:40 -0700, Jason Low wrote:
> On Wed, 2016-04-13 at 06:39 +0800, kbuild test robot wrote:
> > Hi Jason,
> > 
> > [auto build test ERROR on v4.6-rc3]
> > [also build test ERROR on next-20160412]
> > [cannot apply to tip/core/locking]
> > [if your patch is applied to the wrong git tree, please drop us a note to help improving the system]
> > 
> > url:    https://github.com/0day-ci/linux/commits/Jason-Low/MCS-spinlock-Use-smp_cond_load_acquire/20160413-053726
> > config: i386-randconfig-s0-201615 (attached as .config)
> > reproduce:
> >         # save the attached .config to linux build tree
> >         make ARCH=i386 
> > 
> > All error/warnings (new ones prefixed by >>):
> > 
> >    In file included from kernel/locking/qspinlock.c:70:0:
> >    kernel/locking/mcs_spinlock.h: In function 'mcs_spin_lock':
> > >> kernel/locking/mcs_spinlock.h:31:2: error: implicit declaration of function 'smp_cond_load_acquire' [-Werror=implicit-function-declaration]
> >      smp_cond_load_acquire(&l, VAL);     \
> 
> Hello,
> 
> This patch depends on the "smp_cond_load_acquire + cmpwait" patchset,
> which is in:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git locking/rfc

Although I added an extra & in "smp_cond_load_acquire(&l, VAL)" when I
recreated the patch. l is already a pointer, so this call should really
be:

smp_cond_load_acquire(l, VAL);