perf: Merge consecutive conditionals in perf_mmap()

  if (cond) {
    A;
  } else {
    B;
  }

  if (cond) {
    C;
  } else {
    D;
  }

into:

  if (cond) {
    A;
    C;
  } else {
    B;
    D;
  }

Notably the conditions are not identical in form, but are equivalent.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/r/20250812104018.900078502@infradead.org

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9f19c612c80f7ded56915786081ef7effb8d7655..085f36f611375481cf41a5c0b63d2018114a4ff8 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7064,6 +7064,25 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
                if (vma->vm_flags & VM_WRITE)
                        flags |= RING_BUFFER_WRITABLE;
 
+               rb = rb_alloc(nr_pages,
+                             event->attr.watermark ? event->attr.wakeup_watermark : 0,
+                             event->cpu, flags);
+
+               if (!rb) {
+                       ret = -ENOMEM;
+                       goto unlock;
+               }
+
+               atomic_set(&rb->mmap_count, 1);
+               rb->mmap_user = get_current_user();
+               rb->mmap_locked = extra;
+
+               ring_buffer_attach(event, rb);
+
+               perf_event_update_time(event);
+               perf_event_init_userpage(event);
+               perf_event_update_userpage(event);
+               ret = 0;
        } else {
                /*
                 * AUX area mapping: if rb->aux_nr_pages != 0, it's already
@@ -7120,29 +7139,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 
                if (vma->vm_flags & VM_WRITE)
                        flags |= RING_BUFFER_WRITABLE;
-       }
 
-       if (!rb) {
-               rb = rb_alloc(nr_pages,
-                             event->attr.watermark ? event->attr.wakeup_watermark : 0,
-                             event->cpu, flags);
-
-               if (!rb) {
-                       ret = -ENOMEM;
-                       goto unlock;
-               }
-
-               atomic_set(&rb->mmap_count, 1);
-               rb->mmap_user = get_current_user();
-               rb->mmap_locked = extra;
-
-               ring_buffer_attach(event, rb);
-
-               perf_event_update_time(event);
-               perf_event_init_userpage(event);
-               perf_event_update_userpage(event);
-               ret = 0;
-       } else {
                ret = rb_alloc_aux(rb, event, vma->vm_pgoff, nr_pages,
                                   event->attr.aux_watermark, flags);
                if (!ret) {