svn commit: r367088 - head/sys/sys

[Mateusz Guzik]

Author: mjg
Date: Tue Oct 27 18:11:11 2020
New Revision: 367088
URL: https://svnweb.freebsd.org/changeset/base/367088

Log:
  refcount: make it atomic-clean
  
  While here consistently use 'old' in all places.
  
  Tested by:    pho

Modified:
  head/sys/sys/refcount.h

Modified: head/sys/sys/refcount.h
==============================================================================
--- head/sys/sys/refcount.h     Tue Oct 27 18:08:33 2020        (r367087)
+++ head/sys/sys/refcount.h     Tue Oct 27 18:11:11 2020        (r367088)
@@ -63,7 +63,7 @@ refcount_init(volatile u_int *count, u_int value)
 {
        KASSERT(!REFCOUNT_SATURATED(value),
            ("invalid initial refcount value %u", value));
-       *count = value;
+       atomic_store_int(count, value);
 }
 
 static __inline u_int
@@ -95,13 +95,14 @@ refcount_acquiren(volatile u_int *count, u_int n)
 static __inline __result_use_check bool
 refcount_acquire_checked(volatile u_int *count)
 {
-       u_int lcount;
+       u_int old;
 
-       for (lcount = *count;;) {
-               if (__predict_false(REFCOUNT_SATURATED(lcount + 1)))
+       old = atomic_load_int(count);
+       for (;;) {
+               if (__predict_false(REFCOUNT_SATURATED(old + 1)))
                        return (false);
-               if (__predict_true(atomic_fcmpset_int(count, &lcount,
-                   lcount + 1) == 1))
+               if (__predict_true(atomic_fcmpset_int(count, &old,
+                   old + 1) == 1))
                        return (true);
        }
 }
@@ -115,7 +116,7 @@ refcount_acquire_if_gt(volatile u_int *count, u_int n)
 {
        u_int old;
 
-       old = *count;
+       old = atomic_load_int(count);
        for (;;) {
                if (old <= n)
                        return (false);
@@ -174,7 +175,7 @@ refcount_release_if_gt(volatile u_int *count, u_int n)
 
        KASSERT(n > 0,
            ("refcount_release_if_gt: Use refcount_release for final ref"));
-       old = *count;
+       old = atomic_load_int(count);
        for (;;) {
                if (old <= n)
                        return (false);
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