linux-kernel - Re: [RFC v2 1/6] lockdep: Add helper functions of irq

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Date:	Tue, 16 Feb 2016 16:17:28 -0800
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Boqun Feng <boqun.feng@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Josh Triplett <josh@...htriplett.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Lai Jiangshan <jiangshanlai@...il.com>, sasha.levin@...cle.com
Subject: Re: [RFC v2 1/6] lockdep: Add helper functions of irq_context

On Tue, Feb 16, 2016 at 01:57:40PM +0800, Boqun Feng wrote:
> Add two helper functions of irq_context:
> 
> task_irq_context(): return the encoded irq_context of the task, the
> return value is encoded in the same as ->irq_context of held_lock.
> Always return 0 if !(CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING)
> 
> is_same_irq_context(): compare whether two irq_context are the same.
> Always return true if !(CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING)
> 
> These two functions are added for the future use of irq_context by
> LOCKED_ACCESS, because LOCKED_ACCESS needs to get the irq_context value
> of a task when a data access happens rather than when a lock is
> acquired, so it needs another way than getting the value from
> held_lock::irq_context
> 
> Signed-off-by: Boqun Feng <boqun.feng@...il.com>

Queued again for review and testing.  ;-)

							Thanx, Paul

> ---
>  kernel/locking/lockdep.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 60ace56..f36df37 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -2839,6 +2839,16 @@ static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
>  	return 1;
>  }
> 
> +static unsigned int task_irq_context(struct task_struct *task)
> +{
> +	return 2 * (task->hardirq_context ? 1 : 0) + task->softirq_context;
> +}
> +
> +static bool is_same_irq_context(unsigned int ctx1, unsigned int ctx2)
> +{
> +	return ctx1 == ctx2;
> +}
> +
>  static int separate_irq_context(struct task_struct *curr,
>  		struct held_lock *hlock)
>  {
> @@ -2847,8 +2857,7 @@ static int separate_irq_context(struct task_struct *curr,
>  	/*
>  	 * Keep track of points where we cross into an interrupt context:
>  	 */
> -	hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
> -				curr->softirq_context;
> +	hlock->irq_context = task_irq_context(curr);
>  	if (depth) {
>  		struct held_lock *prev_hlock;
> 
> @@ -2880,6 +2889,9 @@ static inline int mark_irqflags(struct task_struct *curr,
>  	return 1;
>  }
> 
> +#define task_irq_context(task)			0
> +#define is_same_irq_context(ctx1, ctx2)		true
> +
>  static inline int separate_irq_context(struct task_struct *curr,
>  		struct held_lock *hlock)
>  {
> -- 
> 2.7.1
>