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From: Konstantin Belousov <kib@FreeBSD.org>
Date: Wed, 26 Sep 2012 09:25:12 +0000 (UTC)
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Subject: svn commit: r240951 - head/sys/kern
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Author: kib
Date: Wed Sep 26 09:25:11 2012
New Revision: 240951
URL: http://svn.freebsd.org/changeset/base/240951

Log:
  Make the updates of the tid ring buffer' head and tail pointers
  explicit by moving them into separate statements from the buffer
  element accesses.
  
  Requested by:	jhb
  MFC after:	3 days

Modified:
  head/sys/kern/kern_thread.c

Modified: head/sys/kern/kern_thread.c
==============================================================================
--- head/sys/kern/kern_thread.c	Wed Sep 26 09:22:28 2012	(r240950)
+++ head/sys/kern/kern_thread.c	Wed Sep 26 09:25:11 2012	(r240951)
@@ -102,8 +102,8 @@ tid_alloc(void)
 		mtx_unlock(&tid_lock);
 		return (-1);
 	}
-	tid = tid_buffer[tid_head++];
-	tid_head %= TID_BUFFER_SIZE;
+	tid = tid_buffer[tid_head];
+	tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
 	mtx_unlock(&tid_lock);
 	return (tid);
 }
@@ -115,11 +115,11 @@ tid_free(lwpid_t tid)
 
 	mtx_lock(&tid_lock);
 	if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) {
-		tmp_tid = tid_buffer[tid_head++];
-		tid_head %= TID_BUFFER_SIZE;
+		tmp_tid = tid_buffer[tid_head];
+		tid_head = (tid_head + 1) % TID_BUFFER_SIZE;
 	}
-	tid_buffer[tid_tail++] = tid;
-	tid_tail %= TID_BUFFER_SIZE;
+	tid_buffer[tid_tail] = tid;
+	tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE;
 	mtx_unlock(&tid_lock);
 	if (tmp_tid != -1)
 		free_unr(tid_unrhdr, tmp_tid);