xnu-2422.115.4.tar.gz

[apple/xnu.git] / iokit / Kernel / IOStatistics.cpp

diff --git a/iokit/Kernel/IOStatistics.cpp b/iokit/Kernel/IOStatistics.cpp
index def362e60fff448676276e77cce1d7d5f1bc04c0..6e72eb49592685df4e862d305f39db7ff9e60293 100644 (file)
--- a/iokit/Kernel/IOStatistics.cpp
+++ b/iokit/Kernel/IOStatistics.cpp
@@ -28,6 +28,7 @@
 
 #include <sys/sysctl.h>
 #include <kern/host.h>
+#include <kern/zalloc.h>
 
 #include <IOKit/system.h>
 #include <libkern/c++/OSKext.h>
@@ -259,10 +260,10 @@ void IOStatistics::onKextUnload(OSKext *kext)
                IOWorkLoopCounter *wlc;
                IOUserClientProcessEntry *uce;
 
-               /* Free up the list of counters */
+               /* Disconnect workloop counters; cleanup takes place in unregisterWorkLoop() */
                while ((wlc = SLIST_FIRST(&found->workLoopList))) {
                        SLIST_REMOVE_HEAD(&found->workLoopList, link);
-                       kfree(wlc, sizeof(IOWorkLoopCounter));
+                       wlc->parentKext = NULL;
                }
 
                /* Free up the user client list */
@@ -520,8 +521,9 @@ void IOStatistics::unregisterWorkLoop(IOWorkLoopCounter *counter)
        }
        
        IORWLockWrite(lock);
-
-       SLIST_REMOVE(&counter->parentKext->workLoopList, counter, IOWorkLoopCounter, link);
+       if (counter->parentKext) {
+               SLIST_REMOVE(&counter->parentKext->workLoopList, counter, IOWorkLoopCounter, link);
+       }
        kfree(counter, sizeof(IOWorkLoopCounter));
        registeredWorkloops--;
        
@@ -1213,8 +1215,13 @@ KextNode *IOStatistics::getKextNodeFromBacktrace(boolean_t write) {
        vm_offset_t *scanAddr = NULL;
        uint32_t i;
        KextNode *found = NULL, *ke = NULL;
-    
-       btCount = OSBacktrace(bt, btCount);
+
+       /*
+        * Gathering the backtrace is a significant source of
+        * overhead. OSBacktrace does many safety checks that
+        * are not needed in this situation.
+        */
+       btCount = fastbacktrace((uintptr_t*)bt, btCount);
 
        if (write) {
                IORWLockWrite(lock);