Reduce the overhead of all trace routines by returning as early as

possible in kd_curproc().

diff --git a/sys/dev/kcov.c b/sys/dev/kcov.c
index b49c6d0..d0f75ed 100644 (file)
--- a/sys/dev/kcov.c
+++ b/sys/dev/kcov.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kcov.c,v 1.39 2021/12/18 08:24:31 anton Exp $ */
+/*     $OpenBSD: kcov.c,v 1.40 2021/12/19 07:45:59 anton Exp $ */
 
 /*
  * Copyright (c) 2018 Anton Lindqvist <anton@openbsd.org>
@@ -553,13 +553,6 @@ kd_curproc(int mode)
 {
        struct kcov_dev *kd;
 
-       /*
-        * Do not trace if the kernel has panicked. This could happen if curproc
-        * had kcov enabled while panicking.
-        */
-       if (__predict_false(panicstr || db_active))
-               return (NULL);
-
        /*
         * Do not trace before kcovopen() has been called at least once.
         * At this point, all secondary CPUs have booted and accessing curcpu()
@@ -571,8 +564,18 @@ kd_curproc(int mode)
        kd = curproc->p_kd;
        if (__predict_true(kd == NULL) || kd->kd_mode != mode)
                return (NULL);
+
+       /*
+        * Do not trace if the kernel has panicked. This could happen if curproc
+        * had kcov enabled while panicking.
+        */
+       if (__predict_false(panicstr || db_active))
+               return (NULL);
+
+       /* Do not trace in interrupt context unless this is a remote section. */
        if (inintr() && kd->kd_intr == 0)
                return (NULL);
+
        return (kd);
 
 }