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[RFC v2 1/6] lockdep: Add helper functions of irq_context

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  [RFC v2 1/6] lockdep: Add helper functions of irq_context Boqun Feng <boqun.feng@gmail.com> - 2016-02-16 07:00 +0100
    Re: [RFC v2 1/6] lockdep: Add helper functions of irq_context "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-02-17 01:20 +0100

#1335035 — [RFC v2 1/6] lockdep: Add helper functions of irq_context

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@gmail.com>
---
 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

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#1335950

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@gmail.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
> 

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