linux-kernel - Re: mmotm 2014-04-24-13-07 uploaded

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Message-ID: <535EBAE6.3080907@infradead.org>
Date:	Mon, 28 Apr 2014 13:32:38 -0700
From:	Randy Dunlap <rdunlap@...radead.org>
To:	paulmck@...ux.vnet.ibm.com, Richard Weinberger <richard@....at>
CC:	Rik van Riel <riel@...hat.com>, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, linux-next@...r.kernel.org,
	umgwanakikbuti@...il.com
Subject: Re: mmotm 2014-04-24-13-07 uploaded

On 04/28/14 13:06, Paul E. McKenney wrote:
> On Mon, Apr 28, 2014 at 07:21:27PM +0200, Richard Weinberger wrote:
>> Am 28.04.2014 19:17, schrieb Randy Dunlap:
>>>
>>> uml defconfig on x86_64:
>>>
>>>   CC      arch/um/kernel/asm-offsets.s
>>> In file included from include/linux/sem.h:5:0,
>>>                  from include/linux/sched.h:35,
>>>                  from arch/x86/um/shared/sysdep/kernel-offsets.h:2,
>>>                  from arch/um/kernel/asm-offsets.c:1:
>>> include/linux/rcupdate.h:257:20: error: static declaration of 'rcu_sysrq_start' follows non-static declaration
>>> include/linux/rcupdate.h:250:6: note: previous declaration of 'rcu_sysrq_start' was here
>>> include/linux/rcupdate.h:260:20: error: static declaration of 'rcu_sysrq_end' follows non-static declaration
>>> include/linux/rcupdate.h:251:6: note: previous declaration of 'rcu_sysrq_end' was here
>>> make[2]: *** [arch/um/kernel/asm-offsets.s] Error 1
>>>
>>>
>>> Please test your patch(es).
> 
> Against exactly what?  ;-)

see $Subject

>> Just in case, to build an x86_64 UML please run:
>>
>> make defconfig ARCH=um SUBARCH=x86_64
>> make linux ARCH=um SUBARCH=x86_64
> 
> Hmmm....  Builds without errors in my local tree.
> 
> Make a clone of linux-next...
> 
> OK, now I get a different build failure:
> 
> /home/paulmck/public_git/linux-next/drivers/tty/sysrq.c:514: undefined reference to `rcu_sysrq_start'
> /home/paulmck/public_git/linux-next/drivers/tty/sysrq.c:558: undefined reference to `rcu_sysrq_end'
> 
> This is due to Rik's "#include <linux/rcupdate.h>" getting lost somehow.
> This #include is needed in drivers/tty/sysrq.c.
> 
> But maybe I need to be using some other branch of linux-next.  Am currently
> on 5bd4e10b96ce20271688aa31d8bd739441249152, which is origin/master.  And
> is also next-20140428.  If I should be somewhere else, please let me know.
> 
> OK, it also appears that my change to make TINY_RCU work is also missing,
> possibly because Randy applied it by hand.

nope.

> Please see below for a patch against next-20140428 that makes this build
> for me.  This is derived from Rik's patch, my patch, and is consistent with
> Arnd's patch.
> 
> 							Thanx, Paul

Thnx, works for me.  Finally.


> ------------------------------------------------------------------------
> 
> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
> index 6c3d11b..38d5f9a 100644
> --- a/drivers/tty/sysrq.c
> +++ b/drivers/tty/sysrq.c
> @@ -46,6 +46,7 @@
>  #include <linux/jiffies.h>
>  #include <linux/syscalls.h>
>  #include <linux/of.h>
> +#include <linux/rcupdate.h>
>  
>  #include <asm/ptrace.h>
>  #include <asm/irq_regs.h>
> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> index e9cc71c..7b0a669 100644
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -247,8 +247,17 @@ void rcu_idle_enter(void);
>  void rcu_idle_exit(void);
>  void rcu_irq_enter(void);
>  void rcu_irq_exit(void);
> +#ifdef CONFIG_RCU_STALL_COMMON
>  void rcu_sysrq_start(void);
>  void rcu_sysrq_end(void);
> +#else /* #ifdef CONFIG_RCU_STALL_COMMON */
> +static inline void rcu_sysrq_start(void)
> +{
> +}
> +static inline void rcu_sysrq_end(void)
> +{
> +}
> +#endif /* #else #ifdef CONFIG_RCU_STALL_COMMON */
>  
>  #ifdef CONFIG_RCU_USER_QS
>  void rcu_user_enter(void);
> diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
> index 20caaf0..a2aeb4d 100644
> --- a/kernel/rcu/update.c
> +++ b/kernel/rcu/update.c
> @@ -322,7 +322,8 @@ int rcu_jiffies_till_stall_check(void)
>  
>  void rcu_sysrq_start(void)
>  {
> -	rcu_cpu_stall_suppress = 2;
> +	if (!rcu_cpu_stall_suppress)
> +		rcu_cpu_stall_suppress = 2;
>  }
>  
>  void rcu_sysrq_end(void)
> 
> --


-- 
~Randy
--
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