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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/211684">211684</a></dd>
<dt>Author</dt> <dd>mark.lam@apple.com</dd>
<dt>Date</dt> <dd>2017-02-05 11:26:50 -0800 (Sun, 05 Feb 2017)</dd>
</dl>
<h3>Log Message</h3>
<pre>The VMInspector should use an RAII Locker.
https://bugs.webkit.org/show_bug.cgi?id=167854
Reviewed by Saam Barati.
Previously, VMInspector::lock() was returning an expected LockToken, and there's
no way to unlock it when we're done with it. This was not a problem before
because the VMInspector had only one client, the SigillCrashAnalyzer, that
expected the process to crash due to a SIGILL shortly thereafter.
However, the VMInspector is useful as a debugging tool that we can apply in other
debugging tasks. Fixing VMInspector::lock() to return an RAII locker will enable
other use cases. Plus it's just bad form to be able to lock something and never
be able to unlock it.
* tools/SigillCrashAnalyzer.cpp:
(JSC::SigillCrashAnalyzer::analyze):
* tools/VMInspector.cpp:
* tools/VMInspector.h:</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoretoolsSigillCrashAnalyzercpp">trunk/Source/JavaScriptCore/tools/SigillCrashAnalyzer.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoretoolsVMInspectorcpp">trunk/Source/JavaScriptCore/tools/VMInspector.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoretoolsVMInspectorh">trunk/Source/JavaScriptCore/tools/VMInspector.h</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (211683 => 211684)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2017-02-05 19:18:16 UTC (rev 211683)
+++ trunk/Source/JavaScriptCore/ChangeLog 2017-02-05 19:26:50 UTC (rev 211684)
</span><span class="lines">@@ -1,3 +1,25 @@
</span><ins>+2017-02-05 Mark Lam <mark.lam@apple.com>
+
+ The VMInspector should use an RAII Locker.
+ https://bugs.webkit.org/show_bug.cgi?id=167854
+
+ Reviewed by Saam Barati.
+
+ Previously, VMInspector::lock() was returning an expected LockToken, and there's
+ no way to unlock it when we're done with it. This was not a problem before
+ because the VMInspector had only one client, the SigillCrashAnalyzer, that
+ expected the process to crash due to a SIGILL shortly thereafter.
+
+ However, the VMInspector is useful as a debugging tool that we can apply in other
+ debugging tasks. Fixing VMInspector::lock() to return an RAII locker will enable
+ other use cases. Plus it's just bad form to be able to lock something and never
+ be able to unlock it.
+
+ * tools/SigillCrashAnalyzer.cpp:
+ (JSC::SigillCrashAnalyzer::analyze):
+ * tools/VMInspector.cpp:
+ * tools/VMInspector.h:
+
</ins><span class="cx"> 2017-02-04 Joseph Pecoraro <pecoraro@apple.com>
</span><span class="cx">
</span><span class="cx"> Static Analyzer: Value stored to 'recordedMachineThreads' during its initialization is never read
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoretoolsSigillCrashAnalyzercpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/tools/SigillCrashAnalyzer.cpp (211683 => 211684)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/tools/SigillCrashAnalyzer.cpp 2017-02-05 19:18:16 UTC (rev 211683)
+++ trunk/Source/JavaScriptCore/tools/SigillCrashAnalyzer.cpp 2017-02-05 19:26:50 UTC (rev 211684)
</span><span class="lines">@@ -241,16 +241,16 @@
</span><span class="cx">
</span><span class="cx"> // Use a timeout period of 2 seconds. The client is about to crash, and we don't
</span><span class="cx"> // want to turn the crash into a hang by re-trying the lock for too long.
</span><del>- auto expectedLockToken = inspector.lock(Seconds(2));
- if (!expectedLockToken) {
- ASSERT(expectedLockToken.error() == VMInspector::Error::TimedOut);
</del><ins>+ auto expectedLocker = inspector.lock(Seconds(2));
+ if (!expectedLocker) {
+ ASSERT(expectedLocker.error() == VMInspector::Error::TimedOut);
</ins><span class="cx"> log("ERROR: Unable to analyze SIGILL. Timed out while waiting to iterate VMs.");
</span><span class="cx"> return;
</span><span class="cx"> }
</span><del>- auto lockToken = expectedLockToken.value();
</del><ins>+ auto& locker = expectedLocker.value();
</ins><span class="cx">
</span><span class="cx"> void* pc = context.machinePC;
</span><del>- auto isInJITMemory = inspector.isValidExecutableMemory(lockToken, pc);
</del><ins>+ auto isInJITMemory = inspector.isValidExecutableMemory(locker, pc);
</ins><span class="cx"> if (!isInJITMemory) {
</span><span class="cx"> log("ERROR: Timed out: not able to determine if pc %p is in valid JIT executable memory", pc);
</span><span class="cx"> return;
</span><span class="lines">@@ -274,7 +274,7 @@
</span><span class="cx"> log("instruction bits at pc %p is: 0x%08x", pc, wordAtPC);
</span><span class="cx"> #endif
</span><span class="cx">
</span><del>- auto expectedCodeBlock = inspector.codeBlockForMachinePC(lockToken, pc);
</del><ins>+ auto expectedCodeBlock = inspector.codeBlockForMachinePC(locker, pc);
</ins><span class="cx"> if (!expectedCodeBlock) {
</span><span class="cx"> if (expectedCodeBlock.error() == VMInspector::Error::TimedOut)
</span><span class="cx"> log("ERROR: Timed out: not able to determine if pc %p is in a valid CodeBlock", pc);
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoretoolsVMInspectorcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/tools/VMInspector.cpp (211683 => 211684)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/tools/VMInspector.cpp 2017-02-05 19:18:16 UTC (rev 211683)
+++ trunk/Source/JavaScriptCore/tools/VMInspector.cpp 2017-02-05 19:26:50 UTC (rev 211684)
</span><span class="lines">@@ -60,7 +60,7 @@
</span><span class="cx"> m_list.remove(vm);
</span><span class="cx"> }
</span><span class="cx">
</span><del>-auto VMInspector::lock(Seconds timeout) -> Expected<LockToken, Error>
</del><ins>+auto VMInspector::lock(Seconds timeout) -> Expected<Locker, Error>
</ins><span class="cx"> {
</span><span class="cx"> // This function may be called from a signal handler (e.g. via visit()). Hence,
</span><span class="cx"> // it should only use APIs that are safe to call from signal handlers. This is
</span><span class="lines">@@ -69,19 +69,19 @@
</span><span class="cx"> // We'll be doing sleep(1) between tries below. Hence, sleepPerRetry is 1.
</span><span class="cx"> unsigned maxRetries = (timeout < Seconds::infinity()) ? timeout.value() : UINT_MAX;
</span><span class="cx">
</span><del>- bool locked = m_lock.tryLock();
</del><ins>+ Expected<Locker, Error> locker = Locker::tryLock(m_lock);
</ins><span class="cx"> unsigned tryCount = 0;
</span><del>- while (!locked && tryCount < maxRetries) {
</del><ins>+ while (!locker && tryCount < maxRetries) {
</ins><span class="cx"> // We want the version of sleep from unistd.h. Cast to disambiguate.
</span><span class="cx"> #if !OS(WINDOWS)
</span><span class="cx"> (static_cast<unsigned (*)(unsigned)>(sleep))(1);
</span><span class="cx"> #endif
</span><del>- locked = m_lock.tryLock();
</del><ins>+ locker = Locker::tryLock(m_lock);
</ins><span class="cx"> }
</span><span class="cx">
</span><del>- if (!locked)
</del><ins>+ if (!locker)
</ins><span class="cx"> return makeUnexpected(Error::TimedOut);
</span><del>- return LockToken::LockedValue;
</del><ins>+ return locker;
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> #if ENABLE(JIT)
</span><span class="lines">@@ -101,7 +101,7 @@
</span><span class="cx"> };
</span><span class="cx"> #endif // ENABLE(JIT)
</span><span class="cx">
</span><del>-auto VMInspector::isValidExecutableMemory(VMInspector::LockToken, void* machinePC) -> Expected<bool, Error>
</del><ins>+auto VMInspector::isValidExecutableMemory(const VMInspector::Locker&, void* machinePC) -> Expected<bool, Error>
</ins><span class="cx"> {
</span><span class="cx"> #if ENABLE(JIT)
</span><span class="cx"> bool found = false;
</span><span class="lines">@@ -133,7 +133,7 @@
</span><span class="cx"> #endif
</span><span class="cx"> }
</span><span class="cx">
</span><del>-auto VMInspector::codeBlockForMachinePC(VMInspector::LockToken, void* machinePC) -> Expected<CodeBlock*, Error>
</del><ins>+auto VMInspector::codeBlockForMachinePC(const VMInspector::Locker&, void* machinePC) -> Expected<CodeBlock*, Error>
</ins><span class="cx"> {
</span><span class="cx"> #if ENABLE(JIT)
</span><span class="cx"> CodeBlock* codeBlock = nullptr;
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoretoolsVMInspectorh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/tools/VMInspector.h (211683 => 211684)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/tools/VMInspector.h 2017-02-05 19:18:16 UTC (rev 211683)
+++ trunk/Source/JavaScriptCore/tools/VMInspector.h 2017-02-05 19:26:50 UTC (rev 211684)
</span><span class="lines">@@ -39,7 +39,7 @@
</span><span class="cx"> TimedOut
</span><span class="cx"> };
</span><span class="cx">
</span><del>- enum class LockToken { LockedValue };
</del><ins>+ typedef WTF::Locker<Lock> Locker;
</ins><span class="cx">
</span><span class="cx"> static VMInspector& instance();
</span><span class="cx">
</span><span class="lines">@@ -46,10 +46,10 @@
</span><span class="cx"> void add(VM*);
</span><span class="cx"> void remove(VM*);
</span><span class="cx">
</span><del>- Expected<LockToken, Error> lock(Seconds timeout = Seconds::infinity());
</del><ins>+ Expected<Locker, Error> lock(Seconds timeout = Seconds::infinity());
</ins><span class="cx">
</span><del>- Expected<bool, Error> isValidExecutableMemory(LockToken, void*);
- Expected<CodeBlock*, Error> codeBlockForMachinePC(LockToken, void*);
</del><ins>+ Expected<bool, Error> isValidExecutableMemory(const Locker&, void*);
+ Expected<CodeBlock*, Error> codeBlockForMachinePC(const Locker&, void*);
</ins><span class="cx">
</span><span class="cx"> private:
</span><span class="cx"> enum class FunctorStatus {
</span></span></pre>
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