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

From: Boqun Feng
Date: Tue Feb 16 2016 - 00:59:24 EST


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@xxxxxxxxx>
---
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