xnu-792.6.56.tar.gz

[apple/xnu.git] / pexpert / i386 / pe_kprintf.c

diff --git a/pexpert/i386/pe_kprintf.c b/pexpert/i386/pe_kprintf.c
index b82d5d43b6be5b91be69760c8eeef0903a50f70b..47788ec82593756d8cecb712d191216b3d4bb2fd 100644 (file)
--- a/pexpert/i386/pe_kprintf.c
+++ b/pexpert/i386/pe_kprintf.c
@@ -3,19 +3,20 @@
  *
  * @APPLE_LICENSE_HEADER_START@
  * 
- * The contents of this file constitute Original Code as defined in and
- * are subject to the Apple Public Source License Version 1.1 (the
- * "License").  You may not use this file except in compliance with the
- * License.  Please obtain a copy of the License at
- * http://www.apple.com/publicsource and read it before using this file.
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
  * 
- * This Original Code and all software distributed under the License are
- * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
- * License for the specific language governing rights and limitations
- * under the License.
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
  * 
  * @APPLE_LICENSE_HEADER_END@
  */
@@ -84,8 +85,17 @@ void kprintf(const char *fmt, ...)
     boolean_t state;
     
     if (!disableSerialOuput) {
-        state = ml_set_interrupts_enabled(FALSE);
-        simple_lock(&kprintf_lock);
+
+       /*
+        * Spin to get kprintf lock but re-enable interrupts while failing.
+        * This allows interrupts to be handled while waiting but
+        * interrupts are disabled once we have the lock.
+        */
+       state = ml_set_interrupts_enabled(FALSE);
+       while (!simple_lock_try(&kprintf_lock)) {
+             ml_set_interrupts_enabled(state);
+             ml_set_interrupts_enabled(FALSE);
+       }
 
        if (cpu_number() != cpu_last_locked) {
            MP_DEBUG_KPRINTF("[cpu%d...]\n", cpu_number());