sched: Introduce preempt_count accessor functions

Replace the single preempt_count() 'function' that's an lvalue with
two proper functions:

 preempt_count() - returns the preempt_count value as rvalue
 preempt_count_set() - Allows setting the preempt-count value

Also provide preempt_count_ptr() as a convenience wrapper to implement
all modifying operations.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-orxrbycjozopqfhb4dxdkdvb@git.kernel.org
[ Fixed build failure. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 8 insertions, 8 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 242da0c03aba..fe89afac4d09 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2219,7 +2219,7 @@ void __kprobes add_preempt_count(int val)
         if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
                 return;
 #endif
-        preempt_count() += val;
+        add_preempt_count_notrace(val);
 #ifdef CONFIG_DEBUG_PREEMPT
         /*
          * Spinlock count overflowing soon?
@@ -2250,7 +2250,7 @@ void __kprobes sub_preempt_count(int val)
 
         if (preempt_count() == val)
                 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
-        preempt_count() -= val;
+        sub_preempt_count_notrace(val);
 }
 EXPORT_SYMBOL(sub_preempt_count);
 
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 53cc09ceb0b8..a90de70cf1f3 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -106,7 +106,7 @@ static void __local_bh_disable(unsigned long ip, unsigned int cnt)
          * We must manually increment preempt_count here and manually
          * call the trace_preempt_off later.
          */
-        preempt_count() += cnt;
+        add_preempt_count_notrace(cnt);
         /*
          * Were softirqs turned off above:
          */
@@ -256,7 +256,7 @@ restart:
                                        " exited with %08x?\n", vec_nr,
                                        softirq_to_name[vec_nr], h->action,
                                        prev_count, preempt_count());
-                                preempt_count() = prev_count;
+                                preempt_count_set(prev_count);
                         }
 
                         rcu_bh_qs(cpu);
diff --git a/kernel/timer.c b/kernel/timer.c
index 4296d13db3d1..6582b82fa966 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1092,7 +1092,7 @@ static int cascade(struct tvec_base *base, struct tvec *tv, int index)
 static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long),
                           unsigned long data)
 {
-        int preempt_count = preempt_count();
+        int count = preempt_count();
 
 #ifdef CONFIG_LOCKDEP
         /*
@@ -1119,16 +1119,16 @@ static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long),
 
         lock_map_release(&lockdep_map);
 
-        if (preempt_count != preempt_count()) {
+        if (count != preempt_count()) {
                 WARN_ONCE(1, "timer: %pF preempt leak: %08x -> %08x\n",
-                          fn, preempt_count, preempt_count());
+                          fn, count, preempt_count());
                 /*
                  * Restore the preempt count. That gives us a decent
                  * chance to survive and extract information. If the
                  * callback kept a lock held, bad luck, but not worse
                  * than the BUG() we had.
                  */
-                preempt_count() = preempt_count;
+                preempt_count_set(count);
         }
 }