X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/6d2010ae8f7a6078e10b361c6962983bab233e0f..04b8595b18b1b41ac7a206e4b3d51a635f8413d7:/iokit/Kernel/IOStatistics.cpp

diff --git a/iokit/Kernel/IOStatistics.cpp b/iokit/Kernel/IOStatistics.cpp
index 9235b293d..6e72eb495 100644
--- 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>
@@ -39,7 +40,6 @@
 #include <IOKit/IOKitDebug.h>
 
 #if IOKITSTATS
-
 bool IOStatistics::enabled = false;
 
 uint32_t IOStatistics::sequenceID = 0;
@@ -178,14 +178,10 @@ void IOStatistics::initialize()
 		return;
 	}
 
-#if DEVELOPMENT || DEBUG
-	/* Always enabled in development and debug builds. */
-#else
-	/* Only enabled in release builds if the boot argument is set. */
+	/* Only enabled if the boot argument is set. */
 	if (!(kIOStatistics & gIOKitDebug)) {
 		return;
 	}
-#endif	
 	
 	sysctl_register_oid(&sysctl__debug_iokit_statistics_general);
 	sysctl_register_oid(&sysctl__debug_iokit_statistics_workloop);
@@ -264,10 +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 */
@@ -525,8 +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--;
 	
@@ -1219,7 +1216,12 @@ KextNode *IOStatistics::getKextNodeFromBacktrace(boolean_t write) {
 	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);
@@ -1230,7 +1232,7 @@ KextNode *IOStatistics::getKextNodeFromBacktrace(boolean_t write) {
 	/* Ignore first levels */
 	scanAddr = (vm_offset_t *)&bt[btMin - 1];
 
-	for (i = 0; i < btCount; i++, scanAddr++) {
+	for (i = btMin - 1; i < btCount; i++, scanAddr++) {
 		ke = RB_ROOT(&kextAddressHead);
 		while (ke) {
 			if (*scanAddr < ke->address) {