Revert "ring-buffer: Move recursive check to per_cpu descriptor"

This reverts commit d6bdff22c8511e4f7d489d180997c929fa7b55b8.

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index d503a73f3736560c604fc1cf6702d1b20fb7163c..520ea0de7894ca16f2dca666857de9c75cc2d048 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -462,7 +462,6 @@ struct ring_buffer_per_cpu {
        arch_spinlock_t                 lock;
        struct lock_class_key           lock_key;
        unsigned int                    nr_pages;
-       unsigned int                    current_context;
        struct list_head                *pages;
        struct buffer_page              *head_page;     /* read from head */
        struct buffer_page              *tail_page;     /* write to tail */
@@ -2676,11 +2675,11 @@ rb_reserve_next_event(struct ring_buffer *buffer,
  * just so happens that it is the same bit corresponding to
  * the current context.
  */
+static DEFINE_PER_CPU(unsigned int, current_context);
 
-static __always_inline int
-trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer)
+static __always_inline int trace_recursive_lock(void)
 {
-       unsigned int val = cpu_buffer->current_context;
+       unsigned int val = __this_cpu_read(current_context);
        int bit;
 
        if (in_interrupt()) {
@@ -2697,21 +2696,20 @@ trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer)
                return 1;
 
        val |= (1 << bit);
-       cpu_buffer->current_context = val;
+       __this_cpu_write(current_context, val);
 
        return 0;
 }
 
-static __always_inline void
-trace_recursive_unlock(struct ring_buffer_per_cpu *cpu_buffer)
+static __always_inline void trace_recursive_unlock(void)
 {
-       cpu_buffer->current_context &= cpu_buffer->current_context - 1;
+       __this_cpu_and(current_context, __this_cpu_read(current_context) - 1);
 }
 
 #else
 
-#define trace_recursive_lock(cpu_buffer)       (0)
-#define trace_recursive_unlock(cpu_buffer)     do { } while (0)
+#define trace_recursive_lock()         (0)
+#define trace_recursive_unlock()       do { } while (0)
 
 #endif
 
@@ -2744,7 +2742,10 @@ ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length)
        preempt_disable_notrace();
 
        if (unlikely(atomic_read(&buffer->record_disabled)))
-               goto out;
+               goto out_nocheck;
+
+       if (unlikely(trace_recursive_lock()))
+               goto out_nocheck;
 
        cpu = raw_smp_processor_id();
 
@@ -2759,18 +2760,16 @@ ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length)
        if (unlikely(length > BUF_MAX_DATA_SIZE))
                goto out;
 
-       if (unlikely(trace_recursive_lock(cpu_buffer)))
-               goto out;
-
        event = rb_reserve_next_event(buffer, cpu_buffer, length);
        if (!event)
-               goto out_unlock;
+               goto out;
 
        return event;
 
- out_unlock:
-       trace_recursive_unlock(cpu_buffer);
  out:
+       trace_recursive_unlock();
+
+ out_nocheck:
        preempt_enable_notrace();
        return NULL;
 }
@@ -2860,7 +2859,7 @@ int ring_buffer_unlock_commit(struct ring_buffer *buffer,
 
        rb_wakeups(buffer, cpu_buffer);
 
-       trace_recursive_unlock(cpu_buffer);
+       trace_recursive_unlock();
 
        preempt_enable_notrace();
 
@@ -2971,7 +2970,7 @@ void ring_buffer_discard_commit(struct ring_buffer *buffer,
  out:
        rb_end_commit(cpu_buffer);
 
-       trace_recursive_unlock(cpu_buffer);
+       trace_recursive_unlock();
 
        preempt_enable_notrace();