linux-kernel - Re: [PATCH 1/5] rcu,nohz: add state parameter to context_tracking_user

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Date:	Fri, 06 Feb 2015 11:15:57 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	paulmck@...ux.vnet.ibm.com, riel@...hat.com
CC:	kvm@...r.kernel.org, borntraeger@...ibm.com,
	linux-kernel@...r.kernel.org, mtosatti@...hat.com,
	mingo@...nel.orgm, ak@...ux.intel.com, oleg@...hat.com,
	masami.hiramatsu.pt@...achi.com, fweisbec@...il.com,
	lcapitulino@...hat.com
Subject: Re: [PATCH 1/5] rcu,nohz: add state parameter to context_tracking_user_enter/exit



On 06/02/2015 00:55, Paul E. McKenney wrote:
> On Thu, Feb 05, 2015 at 03:23:48PM -0500, riel@...hat.com wrote:
>> From: Rik van Riel <riel@...hat.com>
>>
>> Add the expected ctx_state as a parameter to context_tracking_user_enter
>> and context_tracking_user_exit, allowing the same functions to not just
>> track kernel <> user space switching, but also kernel <> guest transitions.
>>
>> Signed-off-by: Rik van Riel <riel@...hat.com>
> 
> Acked-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>

/me wonders: whose tree is supposed to carry these patches?

Paolo

>> ---
>>  include/linux/context_tracking.h | 12 ++++++------
>>  kernel/context_tracking.c        | 10 +++++-----
>>  2 files changed, 11 insertions(+), 11 deletions(-)
>>
>> diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
>> index 37b81bd51ec0..bd9f000fc98d 100644
>> --- a/include/linux/context_tracking.h
>> +++ b/include/linux/context_tracking.h
>> @@ -10,21 +10,21 @@
>>  #ifdef CONFIG_CONTEXT_TRACKING
>>  extern void context_tracking_cpu_set(int cpu);
>>
>> -extern void context_tracking_user_enter(void);
>> -extern void context_tracking_user_exit(void);
>> +extern void context_tracking_user_enter(enum ctx_state state);
>> +extern void context_tracking_user_exit(enum ctx_state state);
>>  extern void __context_tracking_task_switch(struct task_struct *prev,
>>  					   struct task_struct *next);
>>
>>  static inline void user_enter(void)
>>  {
>>  	if (context_tracking_is_enabled())
>> -		context_tracking_user_enter();
>> +		context_tracking_user_enter(IN_USER);
>>
>>  }
>>  static inline void user_exit(void)
>>  {
>>  	if (context_tracking_is_enabled())
>> -		context_tracking_user_exit();
>> +		context_tracking_user_exit(IN_USER);
>>  }
>>
>>  static inline enum ctx_state exception_enter(void)
>> @@ -35,7 +35,7 @@ static inline enum ctx_state exception_enter(void)
>>  		return 0;
>>
>>  	prev_ctx = this_cpu_read(context_tracking.state);
>> -	context_tracking_user_exit();
>> +	context_tracking_user_exit(prev_ctx);
>>
>>  	return prev_ctx;
>>  }
>> @@ -44,7 +44,7 @@ static inline void exception_exit(enum ctx_state prev_ctx)
>>  {
>>  	if (context_tracking_is_enabled()) {
>>  		if (prev_ctx == IN_USER)
>> -			context_tracking_user_enter();
>> +			context_tracking_user_enter(prev_ctx);
>>  	}
>>  }
>>
>> diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
>> index 937ecdfdf258..4c010787c9ec 100644
>> --- a/kernel/context_tracking.c
>> +++ b/kernel/context_tracking.c
>> @@ -47,7 +47,7 @@ void context_tracking_cpu_set(int cpu)
>>   * to execute won't use any RCU read side critical section because this
>>   * function sets RCU in extended quiescent state.
>>   */
>> -void context_tracking_user_enter(void)
>> +void context_tracking_user_enter(enum ctx_state state)
>>  {
>>  	unsigned long flags;
>>
>> @@ -75,7 +75,7 @@ void context_tracking_user_enter(void)
>>  	WARN_ON_ONCE(!current->mm);
>>
>>  	local_irq_save(flags);
>> -	if ( __this_cpu_read(context_tracking.state) != IN_USER) {
>> +	if ( __this_cpu_read(context_tracking.state) != state) {
>>  		if (__this_cpu_read(context_tracking.active)) {
>>  			trace_user_enter(0);
>>  			/*
>> @@ -101,7 +101,7 @@ void context_tracking_user_enter(void)
>>  		 * OTOH we can spare the calls to vtime and RCU when context_tracking.active
>>  		 * is false because we know that CPU is not tickless.
>>  		 */
>> -		__this_cpu_write(context_tracking.state, IN_USER);
>> +		__this_cpu_write(context_tracking.state, state);
>>  	}
>>  	local_irq_restore(flags);
>>  }
>> @@ -118,7 +118,7 @@ NOKPROBE_SYMBOL(context_tracking_user_enter);
>>   * This call supports re-entrancy. This way it can be called from any exception
>>   * handler without needing to know if we came from userspace or not.
>>   */
>> -void context_tracking_user_exit(void)
>> +void context_tracking_user_exit(enum ctx_state state)
>>  {
>>  	unsigned long flags;
>>
>> @@ -129,7 +129,7 @@ void context_tracking_user_exit(void)
>>  		return;
>>
>>  	local_irq_save(flags);
>> -	if (__this_cpu_read(context_tracking.state) == IN_USER) {
>> +	if (__this_cpu_read(context_tracking.state) == state) {
>>  		if (__this_cpu_read(context_tracking.active)) {
>>  			/*
>>  			 * We are going to run code that may use RCU. Inform
>> -- 
>> 1.9.3
>>
> 
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